Geostationary Lightning Mapper (GLM) Reprocessed Level-0 Data

Lockheed Martin has updated six years of GOES-16 and GOES-17 data from the Geostationary Lightning Mapper (GLM), enhancing the accessibility of this crucial information. Previously, the GLM Level-0 (L0) data stored in the Comprehensive Large Array-data Stewardship System (CLASS) at the National Centers for Environmental Information (NCEI) was in a format difficult for users to work with, limiting its potential benefits. To address this, NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) plans to replace the existing L0 archive with this reprocessed data, now in the more user-friendly NetCDF/HDF5 format.

This collection consists of archived L0 data from the GLM aboard the Geostationary Operational Environmental Satellite-R (GOES-R) Series, covering both GOES-East and GOES-West satellites during their operational and post-launch test phases. The GOES-R Series, extending the GOES mission through 2035, enhances our geostationary satellite observation capabilities.

GOES-16, the first satellite of the GOES-R series, began operations as GOES-East on December 18, 2017. GOES-17 followed as GOES-West, starting on February 12, 2019. The reprocessed GLM L0 data spans from March 21, 2017, to September 6, 2022.

The GLM, equipped to detect near-infrared optical transients over the Western Hemisphere, provides data including science, housekeeping, engineering, and diagnostic telemetry, along with orbit and attitude information from the GOES spacecraft. Each data packet, identified by a unique Application Process Identifier (APID) in its header, contains valuable information for interpretation.

For detailed information on the L0 data, the GOES-R Series Product Definition and Users' Guide (PUG) offers comprehensive documentation, including instrument calibration and data reprocessing insights.

Originally, the GLM L0 data was formatted in netCDF-4 with CCSDS packets stored as byte arrays, rendering them unreadable by standard netCDF applications. These were archived as hourly tar files by satellite. The newly reprocessed L0 data, however, is organized into daily files, including both background images (in FITS format) and event data (in netCDF-4), packaged as *.tgz files for easier access and use.

By transitioning to a more accessible NetCDF/HDF5 file format, Lockheed Martin has significantly enhanced the utility of the GLM L0 archive, making it more beneficial for scientific and operational communities.