LTGDISP

Displays GOES-R Series Geostationary Lightning Mapper (GLM) and MTG Lightning Imager (LI) point data.

Format

LTGDISP map gfra [keywords]

Parameters

map	draws and uses the specified map; use any predefined map in the MAP command, e.g., NA, USA, MID, TX, EUR; you cannot use this parameter with the NAV=, LAT= or LON= keyword (default=use navigation of frame specified in the NAV= keyword; no map is drawn)
gfra	graphics frame to display the output (default=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 (default=list of values specified for the COLOR keyword in the MCLTG.USER/.SITE/.CORE text file; the list is set to 5 3 15 4 2 14 12 10 in MCLTG.CORE)
DATaset=	ADDE dataset name and position; specify as group/descriptor.position or alias.position where position is a positive integer (absolute position), or ALL (default=dataset determined by the values specified for the DEFTYPE, GROUP, DESCRIPTOR and POSITION keywords in the MCLTG.USER/.SITE/.CORE text file)
DAY=	eday	ending date for the time range (eday default=current date)
	IMA	uses the day and time of the current image frame
ECHo=	YES	shows the PTDISP commands that are run by LTGDISP (default=NO)
INCrement=	trange tstep	time range and time step in minutes, where: trange defines how many minutes of LTG 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 default=value specified for the INCREMENT keyword in the MCLTG.USER/.SITE/.CORE text file; the increment is set to 5 [minutes] in MCLTG.CORE; tstep default=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 can use this keyword only if nothing or X is specified in the map parameter
LEGend=	ON	prints the color coded increments for the display (default)
	OFF	does not print the legend, the data automatically fills the frame (PTDISP with LINE=1 MAX ELE=1 MAX)
LOC=	symbol size	marks the location of each observation with a centered symbol of the specified size; valid symbols are +, ., * or o and valid sizes are 1-20 (default=values specified for the SYMCHAR and SYMSIZE keywords in the MCLTG.USER/.SITE/.CORE text file; the values are set to + and 8, respectively, in MCLTG.CORE)
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 can use this keyword only if nothing or X is specified in the map parameter
NAV=	frame to use for navigation; specify a frame number or C for current frame (default=C); no map is drawn; you can use this keyword only if nothing or X is specified in the map parameter
PARam=	parameter to plot, e.g., AREA, ENGY, FLSH, GRUP or QUAL (default=plot plus signs [+] at lightning locations using LOC macro settings defined in the MCLTG.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 ground positions (default) NOTE: GLM data is disseminated with parallax correction, i.e. POS=GROUND
	CLOUDTOP	plots the lightning strikes at the cloudtop positions NOTE: MTG LI data is disseminated without parallax correction, i.e. POS=CLOUDTOP
SATs=	ALL	plots data from all datasets matching the lat/lon extents of the image frame (default)
	DEF	plots data from the default dataset specified in the context file
	name	plots data from the satellite name in the context file. Current options are EAST, WEST, and MTG
TDAy=	CAL	prints the calendar day on the default top label (default)
	JUL	prints the Julian day on the default top label
TIMe=	sets the time or times that are used with the INCrement= keyword to determine the time range of LTG data to display; the three formats are listed below; see the Remarks for additional details and examples
	etime	ending time of LTG data to display (default=current time); the beginning time is calculated from the INCrement= keyword
	btime etime	time range of LTG data to display; if using this option you must specify both btime and etime
	IMA	uses the day and time of the current image frame as the ending time of the lightning data to display; the beginning time is calculated from the INCrement= keyword
TOPlabel=	'text' color line ele size text, color, location and size for the top label, where:
		'text'	label's text; 72 characters maximum; specify X without quotes for the default text (default=computed)
		color	graphics color level of the label (default=value specified in the COLor= keyword)
		line	beginning TV line to write the label (default=computed)
		ele	beginning TV element to write the label (default=centered at top of frame)
		size	height of the label text in pixels (default=8)
TYPe=	data type; the valid options are EVEnt, GROup, FLAsh, AF, AFA, AFR (default=value specified for DEFTYPE keyword in MCLTG.USER/.SITE/.CORE text file; the value is set to GROUP in MCLTG.CORE)

Remarks

The LTGDISP command displays GOES-R Series Geostationary Lightning Mapper (GLM) and MTG Lightning Imager (MTG LI) point data. LTGDISP builds and runs one or more PTDISP commands to display the data. If you specify ECHo=YES, the PTDISP commmands are echoed in the text frame so you can see the specific time ranges, colors, etc., for each display.

GOES 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.

MTG Lightning Imager data is arranged in a similar fashion to GOES GLM. The LI-L2-LGR Lightning GRoup product represents the Lightning Groups. The LI-L2-LFL Lightning FLash product represents the Lightning Flashes. The LI-L2-AFA Accumulated Flash Area product represents the area touched by multiple flashes, and the number of flashes per pixel. The LI-L2-AF Accumulated Flash product represents the normalised density of events per pixel from multiple flashes. The LI-L2-AFR Accumulated Flash Radiance product represents the total radiance per pixel from multiple events.

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 and MTG LI cannot distinguish positive from negative flashes. You can use the LOC= keyword, 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 LTG 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 MCLTG.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 LTGDISP and LTGLIST commands use the MCLTG.* context files (where * = .CORE, .SITE and .USER) to set the defaults for many of the commands' parameter and keyword settings. The dataset names in MCLTG.CORE may not be appropriate for users who access their lightning 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 MCLTG.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:

LTGDISP INC=60

This entry displays the lightning 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 MCLTG.CORE/SITE/USER text files. The default will run PTDISP commands to plot Group data from EAST, WEST, and MTG.

LTGDISP TX TYPE=EVENT 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 3, 17:15 to 17:30 in color level 4, 17:30 to 17:45 in color level 2, and 17:45 to 18:00 in color level 6.

LS 10 1-9; ERASE F 1 10; DR 16 4
IMGDISP EAST/CONUS BAND=2 STA=KMIA ALL=1 10 REFRESH='MAP; LTGDISP 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 LTGDISP) 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
LTGDISP TYPE=FLASH TIME=IMA INC=3 COL=6 POS=CLOUD
LTGDISP TYPE=FLASH TIME=IMA INC=3 COL=5 POS=GROUND

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 LTGDISP command (with COL=5 and POS=GROUND) are the default positions, which are parallax-corrected, whereas the data plotted by the first LTGDISP 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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