McIDAS User's Guide
Version 2017.2

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Preliminary Version of GLMDISP Command

GLMDISP | Displays GOES-R Series Geostationary Lightning Mapper (GLM) point data 
  GLMDISP type gfra  

Parameters:
  type  | source type; the valid options are EVEnt, GROup or FLAsh
          (def=value specified for DEFTYPE keyword in GLM.USER/.SITE/.CORE
          text file; the value is set to GROUP in GLM.CORE)
  gfra | graphic frame (def=current)

Keywords:
  COLor=col1..colN | graphics color level for each set of data plotted,
           from newest to oldest; you can specify the colors in the same
           format as frames are specified in the LS command, e.g.,
           COLOR=5 2 for colors 5 and 2, and COLOR=3 5-7 for colors 3,
           5, 6 and 7 (def=list of values specified for the COLOR keyword
           in the GLM.USER/.SITE/.CORE text file; the list is set to 
           5 3 15 4 2 14 12 10 in GLM.CORE)
  DATaset= | ADDE GLM dataset name and position; specify as
             group/descriptor.position or alias.position where position 
             is a positive integer (absolute position), or ALL
             (def=dataset determined by the values specified for the
             DEFTYPE, GROUP, DESCRIPTOR and POSITION keywords in the
             GLM.USER/.SITE/.CORE text file; the values for them in
             GLM.CORE result in the default set to EAST/GLM-GROUP.ALL)
  DAY=bday eday | beginning and ending dates (bday def=current date,
                  eday def=bday)
     =IMA | use the day and time of the current image frame
  INCrement=trange tstep | time range and time step in minutes, where:
               'trange' defines how many minutes of GLM data to display and
               'tstep' defines the number of minutes per time step; for 
               example, INC=5 creates one plot over five minutes in one
               color, and INC=6 2 creates three plots over six minutes in
               three colors; see the Remarks for additional details and
               examples (trange def=value specified for the INCREMENT
               keyword in the GLM.USER/.SITE/.CORE text file; the increment
               is set to 5 (minutes) in GLM.CORE; tstep def=trange)
  LAT= lat1 lat2 | draws and uses a map with its domain defined by lat1 at
                   the lower-right corner, lat2 at the upper-left corner
                   and the longitudes specified in LON=; you cannot use
                   LAT= with NAV= or MAP= 
  LON= lon1 lon2 | draws and uses a map with its domain defined by lon1 at
                   the lower-right corner, lon2 at the upper-left corner
                   and the latitudes specified in LAT=; you cannot use
                   LON= with NAV= or MAP= 
  MAP= | draws and uses the specified map; use any predefined map in the
         MAP command; you cannot use MAP= with NAV=, LAT= or LON=
  NAV= | frame to use for navigation; specify frame number or C for current
         frame (def=C); no map is drawn; you cannot use NAV= with MAP=,
         LAT= or LON=
  PARam= | GLM parameter to plot, e.g., AREA, ENGY, FLSH, GRUP or QUAL
           (def=plot plus signs [+] at lightning locations using LOC macro
           settings defined in the GLM.USER/.SITE/.CORE text file)
  POSition= | position to plot the lightning strikes; valid options are
              GROUND or CLOUDTOP, where:
                - GROUND plots the lightning strikes at the corrected
                  ground positions, keeping the native parallax correction
                  in the GLM file (def)
                - CLOUDTOP plots the lightning strikes at the approximate
                  cloudtop positions as viewed from the GOES-R series
                  satellite, removing the native parallax correction in
                  the GLM file
  TIMe= | sets the time or times that are used with the INCrement=
          keyword to determine the time range of GLM data to display;
          the three formats are listed below; see the Remarks for
          additional details and examples
      =etime | ending time of GLM data to display (def=current time); the
               beginning time is calculated from the INCrement= keyword
      =btime etime | time range of GLM data to display; if using this
                     option you must specify both btime and etime
      =IMA | use the day and time of the current image frame as the ending
             time of the GLM data to display; the beginning time is 
             calculated from the INCrement= keyword

Remarks:
   The GLMDISP command displays GOES-R Series Geostationary Lightning
   Mapper (GLM) point data. GLMDISP builds and runs one or more PTDISP
   commands to display the data. The PTDISP commmands are echoed in the
   text frame so you can see the specific time ranges, colors, etc.,
   for each display.
   
   GLM data processing in the Ground System groups lightning flashes from
   the smallest increments (Events), to aggregates of Events (Groups) to
   aggregates of Groups (Flashes). Thus, Events are on a rectangular grid
   wherein each gridpoint is a GLM Field of View. Groups are plotted at the
   centroid of the Events that comprise the Group, and Flashes are plotted
   at the centroid of the Groups that comprise the Flash. Typically, the
   number of Events is greater than the number of Groups, which is greater
   than the number of Flashes. Real-time GLM datasets normally consist of
   netCDF files that each contain 20 seconds of data. For example, there
   are separate files at 21:25:00, 21:25:20, 21:25:40, 21:26:00, 21:26:20,
   etc., assuming the GLM detected lightning during each of the 
   corresponding 20 second intervals.
   
   The default symbol for plotting the lightning data is a plus sign (+).
   It is used to mark the locations, not the electrical polarity of the
   flash, as the GLM cannot distinguish positive from negative flashes.
   You can use the LOC= keyword from PTDISP, i.e., LOC=o, LOC=. or LOC=*,
   to choose a different symbol.
   
   The TIMe=, DAY= and INCrement= keywords work together to determine the
   time range of GLM data to display and how many time steps (which are each
   plotted separately) to include in the range. If TIME= is not specified
   the time range is from the current time minus the 'trange' value in INC=
   to the current time (e.g., if the current time is 12:15 and INC=60 then
   data from 11:15 to 12:15 are plotted). If you specify a single time or
   'IMA' in TIME= then both 'trange' and 'tstep' in INC= are used. If you
   specify a range of times in TIME= then only 'tstep' in INC= is used
   ('trange' is ignored). The examples below assume that the INC= value
   has not been changed from its default setting of 5 in GLM.CORE.
   TIME=IMA - displays one plot, from 5 minutes before the image time to
              the image time
   TIME=18:15 - displays one plot, from 18:10 to 18:15
   TIME=18:15 INC=5 1 - displays five plots, from 18:10 to 18:11, 
                      18:11 to 18:12, 18:12 to 18:13, 18:13 to 18:14
                      and 18:14 to 18:15
   TIME=18:15 INC=30 10 - displays three plots, from 17:45 to 17:55,
                        17:55 to 18:05 and 18:05 to 18:15
   TIME=18:15 19:15 - displays one plot, from 18:15 to 19:15
   TIME=18:15 19:15 INC=X 10 - displays six plots, from 18:15 to 18:25,
                        18:25 to 18:35, 18:35 to 18:45, 18:45 to 18:55,
                        18:55 to 19:05 and 19:05 to 19:15
   
   The POSition=GROUND/CLOUDTOP keyword lets you choose whether to plot
   the lightning strikes with the parallax correction that is included in
   the GLM files. The default option, GROUND, plots the lightning strikes
   at the ground positions stored in the GLM files. These are approximate
   locations that are parallax corrected based on a latitude-varying
   seasonally-mean tropopause height, not the height where the GLM sensor
   detected the lightning. The CLOUDTOP option removes the parallax 
   correction of the latitude/longitude values in the GLM file. This
   results the locations of the lightning as viewed from the satellite,
   often on the cloud top.
   
   The GLMDISP and GLMLIST commands use the GLM.* context files
   (where * = .CORE, .SITE and .USER) to set the defaults for many of
   the commands' parameter and keyword settings. The dataset names in
   GLM.CORE may not be appropriate for users who access their GLM data
   from somewhere other than SSEC Satellite Data Services. Those users
   may need to specify the datasets they use in the DATASET= keyword,
   or create a GEODATA.USER or .SITE file (see instructions below) and
   add them there.
   
   The .CORE files are supplied with McIDAS-X and should not be modified.
   You can, however, change their settings to your preferences. To do so,
   copy the .CORE file from ~mcidas/data to your $HOME/mcidas/data or
   another MCPATH directory, change its extension from .CORE to .USER or
   .SITE, then edit the settings as needed. The .USER file overrides the
   .SITE file, which overrides the .CORE file. This order of precedence
   ensures that your local settings (in the .USER and/or .SITE file)
   override the settings in the .CORE file.
 
Examples:
  GLMDISP INC=60

  This entry displays the GLM data for the past hour using the navigation
  of the current frame. The type (Group, Event or Flash) and dataset are
  determined by the settings in the GLM.CORE, GLM.SITE and GLM.USER text files.


  GLMDISP EVENT MAP=TX DAY=26/AUG/2017 TIME=18:00 INC=60 15 COLOR=3 4 2 6 DATASET=HARVEY/GLM
  
  This entry displays the GLM data of type EVENT from 17:00 to 18:00 UTC on
  26 August 2017 using the data in dataset HARVEY/GLM. The data is displayed
  over a map of Texas in four 15-minute segments, with 17:00 to 17:15 plotted
  in graphics color level 6, 17:15 to 17:30 in color level 2, 17:30 to 17:45
  in color level 4, and 17:45 to 18:00 in color level 3.


  LS 10 1-9; ERASE F 1 10; DR 16 4
  IMGDISP EAST/CONUS BAND=2 STA=KMIA ALL=1 10 REFRESH='MAP; GLMDISP INC=5 COLOR=5 TIME=IMA' SF=YES
  
  The commands above display a loop of satellite imagery with 5-minute lightning
  strikes plotted over the imagery. The first line (with LS, ERASE and DR) sets
  the loop bounds to frames 1 through 10, erases their contents, and sets a
  longer dwell rate on the last frame (10). The second line (IMGDISP with
  GLMDISP) then displays the ten most recent band 2 images in dataset
  EASTS/CONUS, centered on Miami, FL, and plots the 5-minute accumulated
  lightning strikes in the GLM data that matches the displayed image times
  and domain.
  
  
  IMGDISP EAST/CONUS TIME=21 21:15 STA=KDEN BAND=2
  GLMDISP FLASH TIME=IMA INC=3 COL=6 POS=CLOUD
  GLMDISP FLASH TIME=IMA INC=3 COL=5

  The commands above display a satellite image with both parallax-corrected and
  uncorrected 3-minute lightning strikes plotted over the image. The first line
  (IMGDISP) displays the most recent band 2 image between 21:00 and 21:15 UTC in
  dataset EAST/CONUS, centered on Denver, CO. The second and third lines display
  the corresponding 3-minute accumulated lightning strikes for type FLASH in the
  GLM data that match the displayed image time in graphics color level 6 and 5,
  respectively. The difference is that the data plotted by the second GLMDISP
  command (with COL=5) are the default positions, which are parallax-corrected,
  whereas the data plotted by the first GLMDISP command (with COL=6 and
  POS=CLOUD) have the parallax correction removed so that the lightning plot
  locations match the clouds in the satellite data (which are not parallax
  corrected).
 

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