Gridded GLM Software version 1.0 available
The CSPP Geo project released (linux-based) Gridded GLM software version 1.0 (available for download here) in December of 2022 (This previous CIMSS Blog post discussed a beta version of that software). CSPPGeo Gridded GLM software (Documentation is available here) takes Lightning Cluster Filter Algorithm (LCFA) files and converts the Flash/Event/Group data therein to gridded fields that can be displayed with AWIPS, or with geo2grid, or with other display systems. The gridding algorithms use open-source software such as glmtools developed by Eric Bruning at Texas Tech and colleagues. Output gridded fields include Flash Extent Density, Total Optical Energy, Minimum Flash Area,
Where do the GLM L2+ (i.e., LCFA) files necessary for input into gridded GLM originate? They might come from the GOES Re-Broadcast (GRB) datastream: Direct broadcast users who receive the GOES-East or GOES-West GRB stream on an antenna can run the CSPPGeo GRB software package to generate GLM L2+ and other GOES-R series products in near real-time; any user can download LCFA files from NOAA CLASS by choosing ‘GOES-R Series GLM L2+ Data Product (GRGLMPROD)’; LCFA files are also available via Amazon Web Services, via this handy portal (for example). One could generate data from multiple sources to guard against a data outage in one or more GLM L2+ data feeds!
LCFA files typically have a time cadence of three per minute. For example, the first 12 LCFA files created from GOES-18 on 7 March 2023, that is, the 66th day of year 2023, are shown below. The first file name includes a string that indicates when the data within the file starts, ends, and when it was created
s20230660000000_e20230660000200_c20230660000214. Data in that files starts on day 066 of 2023 at 00:00:00 and ends at 00:00:20; that data file was created at 00:00:21.4. The next file contains data between 00:00:20.0 and 00:00:40.0, then from 00:00:40.0 to 00:01.000, and so on.
Download the (gzipped and tared) gridded GLM software from here (free registration may be required). The call to create the gridded GLM data is straightforward, for example, as shown below using GOES-16 data from 24 January 2023:
sh ./cspp-geo-gglm.sh /path/to/LCFAfiles/accessible/by/your/machine/OR_GLM-L2-LCFA_G16_s20230241804*.nc
This will create the 1-minute aggregate GLM fields valid at 1804 UTC (that is, showing data from 1804 to 1805 UTC) on 24 January 2023, Fields created include Flash Extent Density (FED), Flash Centroid Density (FCD), Average Flash Area (AFA), Total Energy (TOE), Group Extent Density (GED), Group Centroid Density (GCD), Average Group Area (AGA) and Minimum Flash Area (MFA). Gridded GLM software expects that the unix wildcarding will match 3 LCFA files, in the case above from 18:04:00 to 18:04:20, 18:04:20 to 18:04:40 and 18:04:40 to 18:05:00. If one of the three files within the minute are missing, no gridded GLM output is produced, and an error message is produced. In the successful case above, the file created has this name: CG_GLM-L2-GLMF-M3_G16_s20230241804000_e20230241805000_c20230661822210.nc ; note the creation date is 1822 UTC on 7 March, the day I prepared this blog post. By default a Full Disk file is created. However, by adding a -t flag (or using –create-tiles), AWIPS-compatible “punctured” tiles are created, along with statistics files that describe the tiles fully. Amending the command above to include tile-generation
sh ./cspp-geo-gglm.sh -t /arcdata/goes_restricted/grb/goes16/2023/2023_01_24_024/glm/L2/LCFA/OR_GLM-L2-LCFA_G16_s20230241804*
still yields the same file as the first call (although it has a different creation date, so the file name is a bit different), but additional files are created, as listed below. These tiles can then be input into AWIPS and displayed as 1-minute aggregates of various GLM gridded products. The statistics file that describes the tiles is also created. The Global view from these tiled data are shown below, and the same data but zoomed in over Texas are shown above. Note that the data are timestamped in AWIPS as 1805 UTC, the time at which the GLM data ends.
Version 1.0 of gridded GLM allows a user to wildcard more than 1 minute of data at a time. For example, the command “
sh ./cspp-geo-gglm.sh /pathToGLMdata/2023/2023_01_24_024/glm/L2/LCFA/OR_GLM-L2-LCFA_G16_s2023024180[4,5,6,7]*” created four 1-minute GLMF netcdf files.
Coming soon: How to display the gridded GLM data using geo2grid.