McIDAS User's Guide
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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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