Comparison of Data from the North Georgia Lightning Mapping Array and the GOES-16 Global Lightning Mapper

The North Georgia Lightning Mapping Array (NGLMA) is an array of sensors deployed by the Severe Storms Research Center (SSRC) at the Georgia Tech Research Institute. Centered on the metropolitan Atlanta area in north Georgia, the NGLMA uses 12 ground-based sensing stations to detect total lightning, which is the combination of cloud-to-ground and intracloud lighting. The ability of the lightning mapping array (LMA) to accurately measure the time of arrival of the VHF emissions from the lightning at a minimum of 5 ground stations allows a unique position for the VHF source to be calculated. This source data makes up the individual components of a flash, allowing a three dimensional path of the lightning to be plotted. The data is updated every minute and is streamed in real-time to a web site for external partners. It is also sent to the National Weather Service Southern Region Headquarters where it is then made available in the AWIPS II system for use by local forecast offices, such as Peachtree City/Atlanta. One of the objectives of this array is to provide real-time data that improves the situational understanding of NWS forecasters and emergency officials, thereby providing increased lead time for warnings and safety actions. The NGLMA is also used as a research tool by SSRC personnel.

The NGLMA data is currently being used in the calibration and validation of total lighting data from the Global Lightning Mapper (GLM) that is onboard the GOES-16 geostationary satellite that launched last year. In this paper, we will compare total lighting data collected in north Georgia by the NGLMA to the data detected by the GLM over this same area. In order to use the NGLMA source data for comparison, the source data is converted to flash data using “lmatools” (https://github.com/deeplycloudy/lmatools). This tool can sort flashes, determine flash area, and calculate other flash statistics from raw LMA source files. Using these calculated flash data as well as the flash data set files provided by the GLM team, we will compare the flash events in both the spatial and temporal domains for coincidence and detection efficiency.