**-        Basic Instructions for  WINGRIDDS  in  Command Mode:                                                                                                                                         
         A PC based GRidded Information Display and Diagnosis System.                                                                                                                                   
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              All Command Mode requests are input as series of                                                                                                                                          
                     FOUR LETTER INSTRUCTIONS separated                                                                                                                                                 
            by Spaces or Delimiters, followed by the Enter key.                                                                                                                                         
                                                                                                                                                                                                        
                                                                                                                                                                                                        
A guiding template line is displayed at the top of the screen as follows:                                                                                                                               
?____.____.____.____.____.____.____.____.____.____.____.____.____.____.____.___                                                                                                                         
                                                                                                                                                                                                        
NOTE:  With few exceptions, a line of commands is processed in order from                                                                                                                               
                               RIGHT to LEFT,                                                                                                                                                           
        so the last command entered on a line is the first to appear.                                                                                                                                   
                                                                                                                                                                                                        
Additional information on the use of individual commands can be obtained by                                                                                                                             
typing  HLPC  [ HeLP for Commands ]  or by using the Command Help option on                                                                                                                             
the Help Menu.   At any time, you can switch to a menu mode of operations by                                                                                                                            
typing  MENU.                                                                                                                                                                                           
**- To Begin ----------                                                                                                                                                                                 
Before any displays can be generated, a data file must be opened.                                                                                                                                       
                                                                                                                                                                                                        
In Command Mode, WINGRIDDS begins by requesting the  DOS  name of a data file.                                                                                                                          
The file opening process reads and displays a list of fields available from                                                                                                                             
that data set and then initializes a number of Variables used to specify                                                                                                                                
data levels and forecast hours.                                                                                                                                                                         
                                                                                                                                                                                                        
It also establishes a map background for a user specified default portion                                                                                                                               
of the grid area.                                                                                                                                                                                       
                                                                                                                                                                                                        
The  OPEN  command can be make to up to 20 data files available for access.                                                                                                                             
                                                                                                                                                                                                        
The  LIST  command will list the currently grid information variables and                                                                                                                               
the contents of the currently active data set.                                                                                                                                                          
                                                                                                                                                                                                        
The  FILS  command lists the files already opened and their access codes.                                                                                                                               
Once opened, access can change from one file to another using the  FIL#                                                                                                                                 
command, where # is number in order of when the file was opened.                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Initial Default values -                                                                                                                                                                            
The default Flag Variable values are:                                                                                                                                                                   
                                                                                                                                                                                                        
A Forecast Hour (FHOR) -- Default = 12                                                                                                                                                                  
                                                                                                                                                                                                        
A four letter Grid Level (LEVL) -- Default =  850                                                                                                                                                       
                                                                                                                                                                                                        
A pair of Forecast Hours (FHRS) consisting of  -- Default = 00/24                                                                                                                                       
  [See FHR1 and FHR2 later -- Used for time differences, etc.]                                                                                                                                          
                                                                                                                                                                                                        
A grid layer (LAYR) consisting of two levels -- Default = 1000  500                                                                                                                                     
  [See LVL1 and LVL2 later -- Used for level differences, etc.]                                                                                                                                         
                                                                                                                                                                                                        
                                                                                                                                                                                                        
The default values can be customized by the user by including a file named                                                                                                                              
USER\INITGRID.SPC, in which the initial values of the six variable parameters                                                                                                                           
LEVL LVL1 LVL2 FHOR FHR1 FHR2  can be specified.                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Changing Flag Variable Values - Level/Layer Specification                                                                                                                                           
The LeVeL/LaYeR defaults can be Set by typing SLVL or SLYR followed by the                                                                                                                              
four character specifications in the next input positions.  For example,                                                                                                                                
                                                                                                                                                                                                        
SLVL 1000   - Changes default level to 1000 mb,                                                                                                                                                         
SLVL  MSL   - Changes default level to mean sea level,                                                                                                                                                  
SLVL S896   - Changes default level to the Sigma level centered at 896 mb,                                                                                                                              
SLVL I300   - Changes default level to the 300K Isentropic level,                                                                                                                                       
SLYR  850  300   - Changes layer bottom and top default levels (in order)                                                                                                                               
                   to 850 and 300 mb.                                                                                                                                                                   
                                                                                                                                                                                                        
For convenience, the LeVeL can also be specified by simply typing the desired                                                                                                                           
level as part of the command line to the right of the desired field, e.g.,                                                                                                                              
reading from RIGHT to LEFT, the command sequence   TEMP 850   will first set                                                                                                                            
the level to 850 mb and then read, decode and contour the temperature field.                                                                                                                            
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Changing Flag Variable Values - Time Specification                                                                                                                                                  
The time defaults can be changed by typing  FHOR [or SFHR]  or  FHRS [or SFHS]                                                                                                                          
and answering a free-format prompt.                                                                                                                                                                     
                                                                                                                                                                                                        
Alternatively, the time defaults can be changes by typing  SFHR  or  SFHS                                                                                                                               
followed by the desired hour in the next 4 character command line locations.                                                                                                                            
For example,                                                                                                                                                                                            
                                                                                                                                                                                                        
SFHR   12       -  Changes the time default to a 12 hour Forecast,                                                                                                                                      
SFHR   -1       -  Changes the time default to the ANALysis,                                                                                                                                            
SFHR   00       -  Changes the time default to the 00 h initialized fields,                                                                                                                             
SHFS   12   24  -  Changes the time pair defaults to the 12 and 24 h Forecasts.                                                                                                                         
                                                                                                                                                                                                        
For convenience, SFHR can also be omitted from the command string if desired,                                                                                                                           
typing instead only  ANAL, F00, F12, F24, F36 or F48 for those specific times,                                                                                                                          
e.g., reading from RIGHT to LEFT, the command sequence   TEMP 850 F24  will                                                                                                                             
first set the forecast hour to 24 hours, then set the level to 850 mb and                                                                                                                               
lastly read and contour the temperature field..                                                                                                                                                         
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Specifying the Display Area                                                                                                                                                                         
The display area can be changed by typing  AREA  at the LEFT end of the command                                                                                                                         
line, followed a new central latitude and longitude (given by degrees followed                                                                                                                          
immediately by the letters N/S or E/W to indicate hemisphere) and                                                                                                                                       
North-to-South display distance in degrees.  For example, the command sequence                                                                                                                          
AREA 40N 20E 20   will provide a display over southern Europe, extending                                                                                                                                
roughly from 30 to 50 N.                                                                                                                                                                                
                                                                                                                                                                                                        
If no hemisphere indicator is included, positive values are used to represent                                                                                                                           
Northern and Western hemispheric locations.  --  If no lat/lon information is                                                                                                                           
included, a prompt will appear showing location at the center of the grid.                                                                                                                              
                                                                                                                                                                                                        
The Entire grid area can be displayed by entering  AREA followed by 3 zeros,                                                                                                                            
e.g.,  AREA 0 0 0.  The initial display AREA used in each WINGRIDDS session can                                                                                                                         
be specified in a file INITMAP.CRD.                                                                                                                                                                     
                                                                                                                                                                                                        
The Area can also be defined centered at a STatioN location using the  ASTN                                                                                                                             
command followed by a 3 or 4 character station identifier and a North-to-South                                                                                                                          
display distance.  If no N-to-S distance is included, a value of 30 is used.                                                                                                                            
This default can be changed using  NS##, where ## is the N-to-S distance.                                                                                                                               
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Command Structures -- Displaying Primary Data Fields -                                                                                                                                              
Once a file has been opened, data can be displayed by typing a series of                                                                                                                                
requests on the command line.  In general, a command line is read by the                                                                                                                                
program from RIGHT TO LEFT to request grids and perform various functions.                                                                                                                              
Results of the last (left most) operations are then displayed automatically.                                                                                                                            
                                                                                                                                                                                                        
To display any of the grids stored in the gridded data set, simply type the  4                                                                                                                          
letter  NAME  of the grid followed by [Enter]. (Again, a list of the available                                                                                                                          
grids will be show by typing  LIST  .)  For example,                                                                                                                                                    
                                                                                                                                                                                                        
HGHT      - will clear the screen & display contours of the 850 mb HeiGHT field                                                                                                                         
TEMP      - will clear the screen & display contours of the 850 mb TEMPerature                                                                                                                          
                                                                                                                                                                                                        
A listing of the parameters possibly included in the gridded data sets follows:                                                                                                                         
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Primary Gridded Data Fields:                                                                                                                                                                        
HGHT > Geopotential HeiGHT (meters)                                                                                                                                                                     
PRES > Pressure (mb)                                                                                                                                                                                    
                                                                                                                                                                                                        
TEMP > TEMPerature (degree C)                                                                                                                                                                           
THTA > Potential Temperature - THeTA(degree K)                                                                                                                                                          
                                                                                                                                                                                                        
MIXR > MIXing Ratio (g/kg)                                                                                                                                                                              
RELH > Relative Humidity (%)                                                                                                                                                                            
DWPT > DeW Point Temperature (degree C)                                                                                                                                                                 
TMPK > TeMPerature (degrees K)                                                                                                                                                                          
TMPF > TeMPerature (degrees F)                                                                                                                                                                          
THTE > Equivalent Potential Temperature - THeTa/E (degree K)                                                                                                                                            
                                                                                                                                                                                                        
WIND > Total WIND vector (m/sec)                                                                                                                                                                        
WSPD > Total Wind Speed (m/sec)                                                                                                                                                                         
WDDF > Packed value of Wind Direction/speed (tens of degrees and m/sec)                                                                                                                                 
WDRC > Wind DiReCtion (degrees)                                                                                                                                                                         
BWND > WiND Barbs (m/sec)                                                                                                                                                                               
BKNT > Wind Barbs (KNoTs)                                                                                                                                                                               
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Primary Gridded Data Fields (Cont.):                                                                                                                                                                
PMSL > Mean Sea Level Pressure fields, provided without resetting LEVeL                                                                                                                                 
                                                                                                                                                                                                        
TPCP > Total Precipitation fields, provided without resetting LEVeL (mm)                                                                                                                                
CPCP > Convective Precipitation fields, provided without resetting LEVeL (mm)                                                                                                                           
TPCI > Total Precipitation fields, provided without resetting LEVeL (in)                                                                                                                                
CPCI > Convective Precipitation fields, provided without resetting LEVeL (in)                                                                                                                           
                                                                                                                                                                                                        
LIFT > Pre-calculated LIFTed Index, provided without resetting LEVeL                                                                                                                                    
PWAT > Precipitable Water fields, provided without resetting LEVeL                                                                                                                                      
                                                                                                                                                                                                        
THCK > Generates 1000-500 mb Thickness fields                                                                                                                                                           
THWN > Generates 1000-500 mb Thermal Wind                                                                                                                                                               
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Additional automatically derived parameters -                                                                                                                                                       
In addition to displays of LISTed forecast fields already in the data                                                                                                                                   
file, a number of derived parameters and functions can also be requested and                                                                                                                            
calculated automatically as the data are being read from the computer.  For                                                                                                                             
example, a request of  THTA  will automatically calculate and display the                                                                                                                               
potential temperature (THeTA) field.  The automatically calculated derived                                                                                                                              
parameters include:                                                                                                                                                                                     
                                                                                                                                                                                                        
THTA (Potential Temperature)            SDEF (Saturation Deficit)                                                                                                                                       
MIXR (Mixing Ratio)                     SMIX (Saturation Mixing Ratio)                                                                                                                                  
GEOS (Geostrophic Wind - vector)        AGEO (Ageostrophic Wind - vector)                                                                                                                               
LNDX > Provides Lifted Index calculated between LVL1 and LVL2                                                                                                                                           
PLCL > Calculates the Pressure of the LCL from LEVeL data                                                                                                                                               
PDEF > Calculates the Pressure lift needed for saturation form the LCL                                                                                                                                  
ITPV > IsenTropic Potential Vorticity calculated between LVL1 and LVL2 when                                                                                                                             
       LVL1 and LVL2 are set to Theta levels.                                                                                                                                                           
IBPV > IsoBaric Potential Vorticity calculated between LVL1 and LVL2 when                                                                                                                               
       LVL1 and LVL2 are set to pressure levels.                                                                                                                                                        
ITVA > IsenTropic potential Vorticity Advection calculated between LVL1 and                                                                                                                             
       LVL2 when LVL1 and LVL2 are set to Theta levels.                                                                                                                                                 
IBVA > IsoBaric potential Vorticity Advection calculated between LVL1 and                                                                                                                               
       LVL2 when LVL1 and LVL2 are set to pressure levels.                                                                                                                                              
                                                                                                                                                                                                        
See  Command Help  for more commands and detailed explanations.                                                                                                                                         
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Overlaying displays on a single command line -                                                                                                                                                      
Command requests can also be presented in strings, with & (or /) as a command                                                                                                                           
delimiter to indicate field overlays. For example,                                                                                                                                                      
                                                                                                                                                                                                        
RELH&      - will overlay the RELative Humidity analysis on the previously                                                                                                                              
             requested fields in a second color, according to the sequence of                                                                                                                           
             colors on the color bar at the bottom of the screen.                                                                                                                                       
                                                                                                                                                                                                        
TEMP&HGHT  - will display contours of HeiGHTs at 850 mb and the 850 mb                                                                                                                                  
             TEMPerature field in different colors on the same map.                                                                                                                                     
                                                                                                                                                                                                        
NOTE:  All command requests are processed from right to left (a la Reverse                                                                                                                              
Polish Notation).  As such, the command  TEMP&HGHT  will produce a Height                                                                                                                               
field first, followed by a temperature field in a second color.                                                                                                                                         
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Wind Displays -                                                                                                                                                                                     
Vector displays will be generated automatically for vector quantities, or when                                                                                                                          
two grids area queued for plotting.  Again, 4 letter commands can be used to                                                                                                                            
change the mode of display to either arrows  {AROW}  or barbs  {BARB, m/s}.                                                                                                                             
                                                                                                                                                                                                        
Several wind options are available.  These include:                                                                                                                                                     
                                                                                                                                                                                                        
WIND  to display the gridded total wind data,                                                                                                                                                           
GEOS  to display the geostrophic wind, and                                                                                                                                                              
AGEO  to display the ageostrophic wind.        For example,                                                                                                                                             
                                                                                                                                                                                                        
WIND&HGHT  - will display contour of the height field with wind arrows overlaid.                                                                                                                        
                                                                                                                                                                                                        
A number of shorthand alias requests are also available, including                                                                                                                                      
                                                                                                                                                                                                        
WKNT > Retrieves the total wind Vector in knots.                                                                                                                                                        
WMPH > Retrieves the total wind Vector in mph.                                                                                                                                                          
WKPH > Retrieves the total wind Vector in kph.                                                                                                                                                          
BKNT > Retrieves the total wind Vector in knots and sets display as wind barb.                                                                                                                          
BMPH > Retrieves the total wind Vector in mph and sets display as wind barb.                                                                                                                            
BKPH > Retrieves the total wind Vector in kph and sets display as wind barb                                                                                                                             
                                                                                                                                                                                                        
**- Changing Contour Intervals -                                                                                                                                                                        
The Contour INTerval will be calculated automatically based on the variability                                                                                                                          
of the field by default.  Specific Contour INTerval requests can be specified                                                                                                                           
in several ways.  By typing  CINT  to the  left  of a field requested for                                                                                                                               
display, the maximum and minimum of the field will be written on the screen and                                                                                                                         
a prompt for a desired contour interval will appear.  For example,                                                                                                                                      
                                                                                                                                                                                                        
CINT HGHT  -  will read the height field and ask the user for a desired contour                                                                                                                         
              interval (to be input in free format, with a  0  input requesting                                                                                                                         
              an automatically calculated 'reasonable' interval.                                                                                                                                        
                                                                                                                                                                                                        
NOTE:  A contour interval specification normally is only in effect for one plot.                                                                                                                        
To keep a contour specifications from one plot to another, type  CISV .  The                                                                                                                            
contour interval specification mode can be returned to the single plot                                                                                                                                  
convention by typing  CINX.  For example,                                                                                                                                                               
                                                                                                                                                                                                        
HGHT CINX&DWPT&TEMP CISV CIN5  -  will read the TEMPerature and DeWPoinT field                                                                                                                          
                                  and display them with a 5 degree contour and                                                                                                                          
                                  then reset to automatic contour determination                                                                                                                         
                                  and overlay the HeiGHT contours.                                                                                                                                      
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Simplified Contour Interval selection -                                                                                                                                                             
Any contour interval can also be requested without the additional user prompt by                                                                                                                        
including any of the following commands to the left or right of the desired                                                                                                                             
field:                                                                                                                                                                                                  
                                CIN5 - contour intervals of    5 units                                                                                                                                  
Additional options shown        CIN# - contour intervals of    # units                                                                                                                                  
in the command help             CI10 - contour intervals of   10 units                                                                                                                                  
                                CI#0 - contour intervals of   #0 units                                                                                                                                  
                                C100 - contour intervals of  100 units                                                                                                                                  
                                C#00 - contour intervals of  #00 units                                                                                                                                  
                                CI.2 - contour intervals of   .2 units                                                                                                                                  
                                CI.# - contour intervals of   .# units                                                                                                                                  
                                C#+$ - contour intervals of #*10**$ units                                                                                                                               
                                C2+3 - contour intervals of 2000 (10**2) units                                                                                                                          
                                C#-$ - contour intervals of #*10**-$ units                                                                                                                              
                                C2-3 - contour intervals of .002 (10**-2) units                                                                                                                         
For example, the command line -                                                                                                                                                                         
HGHT CI60 SLVL  500&PRES CIN4 SLVL  MSL  -  will display the Mean Sea Level                                                                                                                             
                                            PRESsure field contoured at 4 mb                                                                                                                            
                                            intervals and the 500mb HeiGHTs                                                                                                                             
                                            contoured at 60m intervals.                                                                                                                                 
                                                                                                                                                                                                        
**- Changing Contour Colors / Dashed Contours                                                                                                                                                           
The Contour / Wind display colors will be assigned automatically in sequence                                                                                                                            
according to the template shown at the bottom of the screen.  The default color                                                                                                                         
can be overridden by using the  CLR#  command,                                                                                                                                                          
                                                                                                                                                                                                        
        where CLR1 refers to the first color on the template,                                                                                                                                           
              CLR2 refers to the second color on the template, . . .                                                                                                                                    
              CLRA refers to the tenth color on the template, . . .                                                                                                                                     
              CLRH refers to the first dashed color on the template, . . .                                                                                                                              
              CLRX refers to the first dotted color on the template.                                                                                                                                    
                                                                                                                                                                                                        
Dashed contours can also be produced by including  DASH  in the command line.                                                                                                                           
DASH  is only in effect for one plot and must be reset for additional displays.                                                                                                                         
                                                                                                                                                                                                        
The commands  DNEG  and  DPOS  can be used to dash either the Negative or                                                                                                                               
Positive contours in a data field.                                                                                                                                                                      
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Plotting Digital Grid Values at Data Points / Scaling Output                                                                                                                                        
Digital values of the gridded data can also be requested as follows:                                                                                                                                    
     DATA > Sets display mode to plot data values at grid points.                                                                                                                                       
     DATT > Sets display mode to plot data values above grid points.                                                                                                                                    
     DATB > Sets display mode to plot data values below grid points.                                                                                                                                    
     DATO > Sets display mode to plot data values high Over grid points.                                                                                                                                
     DATU > Sets display mode to plot data values low Under grid points.                                                                                                                                
                                                                                                                                                                                                        
Data Displays and Contour Labels can be requested to display specific digits                                                                                                                            
using the following Scaling and Modulo commands:                                                                                                                                                        
                                                                                                                                                                                                        
     SCL# - Display only signed digits greater than or equal to 10**#                                                                                                                                   
     SCL0 - Display only signed digits greater than or equal to 10**0 (1)                                                                                                                               
     SCL1 - Display only signed digits greater than or equal to 10**1 (10)                                                                                                                              
     SC-# - Display only signed digits greater than or equal to 10**-#                                                                                                                                  
     SC-1 - Display only signed digits greater than or equal to 10**-1 (.1)                                                                                                                             
                                                                                                                                                                                                        
     MOD# > Display labels using Modulo of SCALED display value and 10**#                                                                                                                               
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Changing Wind Arrow Length or Displaying Wind Barbs -                                                                                                                                               
The contour interval specification also acts as means for changing the length                                                                                                                           
of arrows used in wind displays.  Normally, the lengths of wind arrows are                                                                                                                              
scales so that the arrow representing the largest wind speed in a display is                                                                                                                            
set to be equal to the distance between to adjacent grid points.  Adjustments                                                                                                                           
in the length can be made using the "CI" commands, where the requested "contour                                                                                                                         
interval" specifies the speed to be plotted as a one grid interval length                                                                                                                               
arrow.  For example,                                                                                                                                                                                    
                                                                                                                                                                                                        
WIND CI10  -  will produce wind arrows in which the length of a 10 m/s wind                                                                                                                             
              is one grid spacing unit.                                                                                                                                                                 
                                                                                                                                                                                                        
                                                                                                                                                                                                        
Winds can also be displayed as barbs by typing  BARB.                                                                                                                                                   
                                                                                                                                                                                                        
Winds can also be displayed as streamlines by typing  STRM.                                                                                                                                             
                                                                                                                                                                                                        
To return the wind display to Arrows type  AROW.                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Use of Layers or Multiple time periods -                                                                                                                                                            
Layer and/or time manipulation of PRIMARY DATA VARIABLES can be triggered by                                                                                                                            
inserting keywords to the right of the desired variable.  Options include:                                                                                                                              
                                                                                                                                                                                                        
LDIF (Layer Difference)    LAVE (Layer Average)    LTOT (Layer Sum or Total)                                                                                                                            
   TDIF (Time Difference)                  TAVE (Time Average)                                                                                                                                          
   TTND (Time Tendency - TDIF/time)        TTOT (Time Sum or Total)                                                                                                                                     
                                                                                                                                                                                                        
NOTE: These commands MUST be positioned to the RIGHT of the variable name and                                                                                                                           
can ONLY be used with PRIMARY VARIABLES.                                                                                                                                                                
                                                                                                                                                                                                        
For example, the sequence of commands                                                                                                                                                                   
                                                                                                                                                                                                        
SLYR 1000  500  -  will calculate the DIFference in HGHT between the top and                                                                                                                            
HGHT LDIF          bottom levels defined by the SLYR command, in this case                                                                                                                              
                   producing a 1000 to 500 mb thickness field, and                                                                                                                                      
                                                                                                                                                                                                        
SFRS  F00  F24  - will calculate and display the difference                                                                                                                                             
HGHT TDIF         in the HeiGHT fields between the initial conditions and the                                                                                                                           
                  24 h forecast.                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Use of Layers or Multiple time periods (Continued) -                                                                                                                                                
Calculations using either the top or bottom levels of the layer defined by                                                                                                                              
SLYR and/or the beginning or end times of a forecast period defined by FHRS can                                                                                                                         
be requested without explicitly resetting the level or time defaults by                                                                                                                                 
inserting the following keywords to the right of the desired variable:                                                                                                                                  
                                                                                                                                                                                                        
LVL1 (First level of LAYR)              LVL2 (Second level of LAYR)                                                                                                                                     
FHR1 (First time of FHRS)               FHR2 (Second time of FHRS)                                                                                                                                      
                                                                                                                                                                                                        
For example, the command line                                                                                                                                                                           
                                                                                                                                                                                                        
HGHT LDIF&HGHT LVL2&HGHT LVL1 CI60 SLYR 1000  500  -  will set the layer limits                                                                                                                         
                                                      at 1000 and 500 mb and                                                                                                                            
                                                      then produce contours of                                                                                                                          
NOTE:  Once a layer or time period has                the 1000 and 500 mb                                                                                                                               
       set, it continues in effect for                HeiGHTs, followed by the                                                                                                                          
       remainder of that plot request                 1000-500 mb thickness,                                                                                                                            
       unless overturned by another entry.            all contoured with 60 m                                                                                                                           
                                                      intervals.                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Specify a Cross Section Path                                                                                                                                                                        
Cross-section displays can be established by typing  XSCT  followed by the left                                                                                                                         
display latitude and longitude and the right latitude and longitude. (Again,                                                                                                                            
if the lat/lon information is not included, a prompt will appear.)  Two formats                                                                                                                         
can be used, either latitudes and longitudes followed IMMEDIATELY (no spaces                                                                                                                            
between) by 1 character hemisphere indicators (e.g., 40S  for 40 degrees South                                                                                                                          
latitude) or signed numeric values, where positive values indicate Northern and                                                                                                                         
Western Hemispheres.                                                                                                                                                                                    
                                                                                                                                                                                                        
Cross-sections can also be defined between two Stations locations using the                                                                                                                             
XSTN  command followed by two 3 or 4 letter stations identifiers. Once a                                                                                                                                
cross-section has been defined, the base map can be redrawn with the cross                                                                                                                              
section path shown as a dotted line using either the  MAP  command (to overlay                                                                                                                          
a map on the existing product) or the  EMAP  command to erase the screen before                                                                                                                         
drawing the map.  The cross-section specification and corresponding map display                                                                                                                         
can be removed by entering  XSTN  alone.                                                                                                                                                                
                                                                                                                                                                                                        
Defining of a cross section path also initiates the cross section display mode.                                                                                                                         
                                                                                                                                                                                                        
Display modes can be switched from cross section to plan view by typing  PLAN,                                                                                                                          
and from plan view to the previously established cross section by typing  CROS.                                                                                                                         
                                                                                                                                                                                                        
**- Cross Section Wind displays                                                                                                                                                                         
Cross-sectional wind displays can be modified to provide rotated, cross-section                                                                                                                         
relative wind representations by typing  XREL  to the left of the desired wind                                                                                                                          
type. Individual cross-sectional relative components can be displayed using                                                                                                                             
TANG  and  NORM  for contour of the tangential and normal wind components and                                                                                                                           
VTNG  and  VNRM  for vector component displays.                                                                                                                                                         
                                                                                                                                                                                                        
Vertical circulations displays of the tangential component of the wind and the                                                                                                                          
vertical velocity can produced by typing  VCRC  followed by a wind type.                                                                                                                                
                                                                                                                                                                                                        
A number of shorthand notations aliases are available for cross-sectional                                                                                                                               
wind displays, including:                                                                                                                                                                               
                                                                                                                                                                                                        
WNDX  to display the total wind rotated relative to the cross section,                                                                                                                                  
GEOX  to display the geostrophic wind rotated relative to the cross section,                                                                                                                            
AGEO  to display the ageostrophic wind rotated relative to the cross section,                                                                                                                           
WCRC  to display vertical/tangential circulations of total wind,                                                                                                                                        
GCRC  to display vertical/tangential circulations of geostrophic wind,                                                                                                                                  
ACRC  to display vertical/tangential circulations of ageostrophic wind.                                                                                                                                 
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Diagnostic Functions - Background and Philosophy -                                                                                                                                                  
The system includes the ability to calculate and combine a variety of quantities                                                                                                                        
derived from the grid point data greatly enhances the diagnostic capabilities of                                                                                                                        
the system.  The diagnostics are expressed in functional form, in that a                                                                                                                                
function name is followed by an ordered set of arguments, optionally enclose in                                                                                                                         
parentheses or brackets and separated by commas.                                                                                                                                                        
                                                                                                                                                                                                        
As an illustration, advection is expressed as the function  ADVT  followed by a                                                                                                                         
Scalar quantity and a Wind Type.  As such, the Temperature Advection field                                                                                                                              
should be thought of as "ADVecTion of the TEMPerature by the Total WIND" and                                                                                                                            
correspondingly requested using the sequence  ADVT(TEMP,WIND).  Similarly, the                                                                                                                          
ageostrophic component of the Moisture Advection is expressed as "ADVecTion of                                                                                                                          
the MIXing Ratio by the AGEOstropic wind" and requested by  ADVT(MIXR,AGEO).                                                                                                                            
Here, both the Mixing Ratio and Ageostrophic Wind are derived automatically.                                                                                                                            
                                                                                                                                                                                                        
Functional call can also be chained together.  For example, Vorticity Advection                                                                                                                         
is thought of as the "Advection of the Vorticity of the Total Wind by the Total                                                                                                                         
Wind."  As such, the functional request becomes  ADVT[VORT(WIND),WIND].                                                                                                                                 
                                                                                                                                                                                                        
For clarity, either parentheses - ( and ) - or brackets - [ and ] - can, as an                                                                                                                          
option, be used to group the function arguments.                                                                                                                                                        
                                                                                                                                                                                                        
**- Available Diagnostic Functions -                                                                                                                                                                    
See the Command Help option for full listing of available commands.                                                                                                                                     
Some frequently used functions available, include:                                                                                                                                                      
                                                                                                                                                                                                        
SSUM [Followed by 2 Scalars] > Calculates Scalar grid sum                                                                                                                                               
SAVR [Followed by 2 Scalars] > Calculates Scalar grid average                                                                                                                                           
SDIF [Followed by 2 Scalars] > Calculates Scalar grid difference                                                                                                                                        
STND [Followed by 2 Scalars] > Calculates Scalar grid time tendency                                                                                                                                     
SMLT [Followed by 2 Scalars] > Multiplies two Scalar fields                                                                                                                                             
SDVD [Followed by 2 Scalars] > Divides two Scalar fields                                                                                                                                                
SADC [Followed by a 4 digit value] > Sum of Scalar & specified constant                                                                                                                                 
SSBC [Followed by a 4 digit value] > Difference of Scalar & specified constant                                                                                                                          
SMLC [Followed by a 4 digit value] > Multiplies Scalar by specified constant                                                                                                                            
SDVC [Followed by a 4 digit value] > Divides Scalar by specified constant                                                                                                                               
INVS [Followed by a Scalar] > Finds INVerSe of a Scalar                                                                                                                                                 
INV1 [Followed by a Scalar] > Finds INVerse of a Scalar with max. of 1                                                                                                                                  
ABSV [Followed by Scalar] > Calculates ABSolute Value of Scalar grid                                                                                                                                    
SINE [Followed by Scalar] > Calculates the SINE of Scalar grid (e.g., WDRC)                                                                                                                             
COSN [Followed by Scalar] > Calculates the COSiNe of Scalar grid (e.g., WDRC)                                                                                                                           
TNGT [Followed by Scalar] > Calculates the TaNGenT of Scalar grid (e.g., WDRC)                                                                                                                          
SNEG [Followed by Scalar] > Finds the NEGative of a Scalar grid                                                                                                                                         
                                                                                                                                                                                                        
**- Diagnostic Functions (Cont.):                                                                                                                                                                       
DSDX [Followed by Scalar] > Calculates X gradient of Scalar                                                                                                                                             
DSDY [Followed by Scalar] > Calculates Y gradient of Scalar                                                                                                                                             
MGRD [Followed by a Scalar] > Magnitude of the GRaDient of a Scalar field                                                                                                                               
GRAD [Followed by a Scalar] > Finds the GRADient of a Scalar field                                                                                                                                      
NGRD [Followed by a Scalar] > Finds the Negative GRaDient of a Scalar field                                                                                                                             
MGRD [Followed by a Scalar] > Magnitude of the GRaDient of a Scalar field                                                                                                                               
                                                                                                                                                                                                        
VADC [Followed by a 4 digit value] > Sum of Vector & specified constant                                                                                                                                 
VSBC [Followed by a 4 digit value] > Difference of Vector & specified constant                                                                                                                          
VMLC [Followed by a 4 digit value] > Multiplies Vector by specified constant                                                                                                                            
VDVC [Followed by a 4 digit value] > Divides Vector by specified constant                                                                                                                               
VNEG [Followed by Vector] > Finds the NEGative of a Vector field                                                                                                                                        
VSUM [Followed by 2 Vectors] > Calculates the Vector sum                                                                                                                                                
VAVR [Followed by 2 Vectors] > Calculates the Vector average                                                                                                                                            
VDIF [Followed by 2 Vectors] > Calculates the Vector difference                                                                                                                                         
VTND [Followed by 2 Vectors] > Calculates the Vector time tendency                                                                                                                                      
VMLT [Followed by 2 Vectors] > Multiplies two Vectors by components                                                                                                                                     
DOTP [Followed by 2 Vectors] > Calculates the DOT Product of 2 Vectors                                                                                                                                  
CRSP [Followed by 2 Vectors] > Calculates the CRoSs Product of two Vectors                                                                                                                              
VDVD [Followed by 2 Vectors] > Divides two Vectors by components                                                                                                                                        
                                                                                                                                                                                                        
**- Diagnostic Functions (Cont.):                                                                                                                                                                       
VKNT [Followed by a Vector] > Converts a Vector from m/s to KNoTs                                                                                                                                       
VMPH [Followed by a Vector] > Converts a Vector from m/s to MPH                                                                                                                                         
VKPH [Followed by a Vector] > Converts a Vector from m/s to KPH                                                                                                                                         
MAGN [Followed by a Vector] > Calculates MAGNitude of a Vector                                                                                                                                          
SKNT [Followed by a Scalar] > Converts a Scalar (e.g., WSPD) from m/s to KNOTs                                                                                                                          
SMPH [Followed by a Scalar] > Converts a Scalar (e.g., WSPD) from m/s to MPH                                                                                                                            
SKPH [Followed by a Scalar] > Converts a Scalar (e.g., WSPD) from m/s to KPH                                                                                                                            
                                                                                                                                                                                                        
ADVT [Followed by Scalar and Vector] > Calculates advection                                                                                                                                             
DVRG [Followed by a Vector] > Calculates divergence                                                                                                                                                     
FLUX [Followed by a Scalar & a Vector] > Produces a flux Vector                                                                                                                                         
SDVR [Followed by Scalar and Vector] > Calculates flux divergence                                                                                                                                       
RVRT [Followed by a Vector] > Calculates relative vorticity                                                                                                                                             
VORT [Followed by a Vector] > Calculates absolute vorticity                                                                                                                                             
SMTH > Applies a binomial smoother to the active Scalar gridded data                                                                                                                                    
VSMT > Applies a binomial smoother to the active Vector gridded data                                                                                                                                    
ZPOS > Sets all positive values to zero                                                                                                                                                                 
ZNEG > Sets all negative values to zero                                                                                                                                                                 
RLTN [Followed by a 4 digit value] > Replaces values Less ThaN with that value                                                                                                                          
RGTN [Followed by a 4 digit value] > Replaces values Greater ThaN with value                                                                                                                            
                                                                                                                                                                                                        
**- Diagnostic Functions (Cont.) - Cross Section Specific:                                                                                                                                              
XREL [Followed by Vector] > Rotates Vector from earth to cross sector relative                                                                                                                          
TANG [Followed by Vector] > Finds cross-section relative tangential component                                                                                                                           
VTNG [Followed by Vector] > Plots cross-section relative tangential component                                                                                                                           
VCRC [Followed by Vector] > Plots VTNG & VVEL                                                                                                                                                           
VCR2 [Followed by Vector] > Plots VTNG & VVEL scaled by 2                                                                                                                                               
VCR5 [Followed by Vector] > Plots VTNG & VVEL scaled by 5                                                                                                                                               
NORM [Followed by Vector] > Finds cross-section relative normal component                                                                                                                               
VNRM [Followed by Vector] > Plots cross-section relative normal component                                                                                                                               
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Examples of Diagnostic Functions -                                                                                                                                                                  
Some sample diagnostic command sequences include,                                                                                                                                                       
                                                                                                                                                                                                        
MAGN(WIND)      -  will calculate and display isotachs of the MAGNitude of the                                                                                                                          
                   total WIND,                                                                                                                                                                          
SDIF(MIXR,SMIX) -  will produce the difference between the true and Saturation                                                                                                                          
                   MIXing Ratios  --- the saturation deficit.                                                                                                                                           
ADVT[TEMP,WIND] -  will produce the TEMPerature ADVecTion field using the total                                                                                                                         
                   WIND, - Note brackets/parends are interchangeable.                                                                                                                                   
ADVT TEMP GEOS  -  will produce the TEMPerature ADVecTion field using the                                                                                                                               
                   GEOStrophic wind, - Note brackets can be omitted                                                                                                                                     
ADVT(PRES,WIND) S982 - will set the default level to the bottom sigma level                                                                                                                             
                   of the NGM and calculate the ADVecTion of PRESsure on a                                                                                                                              
                   sigma surface by the WIND, a measure of the orographic                                                                                                                               
                   vertical motion,                                                                                                                                                                     
DVRG[WIND]      -  will calculate and display the DiVeRGence of the total WIND,                                                                                                                         
SDVR(MIXR,WIND) -  will contour the Scalar flux DiVeRgence of the MIXing Ratio                                                                                                                          
                   using the total WIND, etc.                                                                                                                                                           
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- Shorthand specifications and Commonly Used Diagnostic Functions -                                                                                                                                   
For simplicity, frequently used sequences of commands can be grouped together                                                                                                                           
and given a 4 character ALIAS name.  These alias names can be used in exactly                                                                                                                           
the same fashion as all other WINGRIDDS commands, with the difference that they                                                                                                                         
are completely user defined in the file  USER\ALIAS.DAT.                                                                                                                                                
                                                                                                                                                                                                        
Some predefined systems aliased diagnostic commands include,                                                                                                                                            
                                                                                                                                                                                                        
WSPD > Generates isotachs for the Total wind                                                                                                                                                            
WVRT > Generates vorticity of the Total wind                                                                                                                                                            
GVRT > Generates vorticity of the Geostrophic wind                                                                                                                                                      
THCK |TKNS| > Generates 1000-500 mb Thickness fields                                                                                                                                                    
THWN |TWND| > Generates 1000-500 mb Thermal Wind                                                                                                                                                        
                                                                                                                                                                                                        
TADV > Generates Temperature Advection using the Total wind                                                                                                                                             
QADV > Generates Mixing Ratio Advection using the Total wind                                                                                                                                            
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**-Saving and Restoring Pre-Generated Graphics                                                                                                                                                          
Plots can be saved for rapid redisplay by typing the command  SAVE  followed by                                                                                                                         
a space and a 4-character file name (the qualifier .SVG will also be added                                                                                                                              
automatically).  All plot commands will saved until the command  ENDS is used.                                                                                                                          
To restore the saved plot file, either type  REST  followed by the file name                                                                                                                            
(again without the .SVG qualifier) or type the file name followed by a                                                                                                                                  
semicolon.  The results will be displayed over whatever is on the screen                                                                                                                                
already, so be sure to erase the existing graphics using  ERAS  is you do not                                                                                                                           
want the graphics overlaid on the existing screen display.  The .SVG files can                                                                                                                          
also be used to produce hard-copy on HP laser printers.                                                                                                                                                 
                                                                                                                                                                                                        
For example, the sequence of commands -                                                                                                                                                                 
SAVE 500Z                                                                                                                                                                                               
VORT WIND&HGHT SLVL  500                                                                                                                                                                                
ENDS                                                                                                                                                                                                    
ERAS                                                                                                                                                                                                    
REST 500Z   [This command line could alternatively be input at  500Z; ]                                                                                                                                 
                                                                                                                                                                                                        
  -  will create a .SVG file labeled 500Z.SVG, generate contours of the 500 mb                                                                                                                          
     HeiGHT and VORTicity fields and save the plotting commands, close the .SVG                                                                                                                         
     file, erase the screen and then restore graphics.                                                                                                                                                  
                                                                                                                                                                                                        
**- Repeating previous commands                                                                                                                                                                         
A list of the previous 21 commands input from the keyboard is given by entering                                                                                                                         
the command  CMDS.  This command ERASES the screen.  Individual commands can be                                                                                                                         
examined without erasing the screen by using the command  CMD#,  where # is the                                                                                                                         
order number of the previous command, e.g., CMD2 will list the 2nd previous                                                                                                                             
command.  For commands 10 through 21, the letters A through L are used.                                                                                                                                 
                                                                                                                                                                                                        
A previous command can be repeated by using the command  RPT#,  where again #                                                                                                                           
refers to the order number of the previous command.  The command results can                                                                                                                            
be overlaid on the existing graphics by including a  &  after the command.  As                                                                                                                          
such,  RPTB&  will overlay the 11th previous command on the existing graphics.                                                                                                                          
                                                                                                                                                                                                        
A historical record of all commands used in a particular session is stored in                                                                                                                           
the file COMMAND.OUT.  Reference to particularly complicated commands from this                                                                                                                         
file can simplify writing the command files to be described next.                                                                                                                                       
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
**- COMMAND {MACRO} FILES -                                                                                                                                                                             
A command file is simply a sequence of command lines to be executed in series,                                                                                                                          
and can be used as shorthand notations for frequently used or particularly                                                                                                                              
command sequences or to produce pre-defined products.                                                                                                                                                   
                                                                                                                                                                                                        
Pre-specified sequences of command lines can be written into an ASCII file                                                                                                                              
using any word processor.  The Command File can be given any  4  letter  NAME                                                                                                                           
and must be followed by the qualifier ".CMD".  To execute the Command File,                                                                                                                             
type the file NAME at the BEGINNING of a command line, followed IMMEDIATELY by                                                                                                                          
a period.  The requested command lines will be displayed in sequence, with a                                                                                                                            
prompt to press  [Enter]  displayed between commands lines.                                                                                                                                             
                                                                                                                                                                                                        
Loops can also be set up by including the word  LOOP  alone at the beginning of                                                                                                                         
any line of the Command File.  Loops are ended by including the command line                                                                                                                            
ENDL.  User prompts at the end of each command line are NOT given while in LOOP                                                                                                                         
mode. Pauses between looped command lines can be included by adding the                                                                                                                                 
commands 1SEC, 3SEC, 5SEC, 7SEC, or 9SEC, depending on the number of seconds                                                                                                                            
desired.                                                                                                                                                                                                
                                                                                                                                                                                                        
Annotation can also be added to any line on the screen using the  TXT#                                                                                                                                  
command.  For example,  'TXTC  This is line 3' will write the test on the third                                                                                                                         
line of the screen.                                                                                                                                                                                     
**- Sample  COMMAND FILE -                                                                                                                                                                              
A sample Command File containing -                                                                                                                                                                      
                                                                                                                                                                                                        
WIND CINX&TEMP CIN5&HGHT CI60 SLVL  850  F00                                                                                                                                                            
LOOP                                                                                                                                                                                                    
WIND CINX&TEMP CIN5&HGHT CI60  F12                                                                                                                                                                      
WIND CINX&TEMP CIN5&HGHT CI60  F24 5SEC                                                                                                                                                                 
WIND CINX&TEMP CIN5&HGHT CI60  F36 5SEC                                                                                                                                                                 
WIND CINX&TEMP CIN5&HGHT CI60  F48 5SEC                                                                                                                                                                 
ENDL                                                                                                                                                                                                    
                                                                                                                                                                                                        
  -  will display the initial 850 mb heights, temperatures and winds, request                                                                                                                           
     the user to press  [Enter], and then display a loop of the 12, 24, 36,                                                                                                                             
     and 48 h forecasts, pausing 5 seconds between each completed graphic.                                                                                                                              
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
                                                                                                                                                                                                        
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