Defining interest fields for 0-1 hour lighting initiation using GOES infrared temperature and reflectance data

Within cumulus cloud fields that develop in conditionally unstable air masses, only a fraction of the cumuli may eventually develop into deep convection. Identifying which of these convective clouds most likely to generate lightning often starts with little more than a qualitative visual satellite analysis. The goal of this study is to identify the observed satellite infrared (IR) signatures associated with growing cumulus clouds prior to the first lightning strike, so–called lightning initiation (LI). This study quantifies the behavior of ten Geostationary Operational Environmental Satellite (GOES–12) IR interest fields in the 1-hour in advance of LI. A total of 172 lightning–producing storms that occurred during the 2009 convective season are manually tracked and studied over four regions: Northern Alabama, Central Oklahoma, the Kennedy Space Center and Washington D.C. Four–dimensional and cloud–to–ground lightning array data provide a total cloud lightning picture (in–cloud, cloud–to–cloud, cloud–to–air, cloud–to–ground) and thus precise LI points for each storm in both time and space.

Statistical significance tests are conducted on observed trends for each of the ten LI fields to determine the unique information each field provides in terms of behavior prior to LI. Eight out of ten LI fields exhibited useful information at least 15 min in advance of LI, with 35 min being the average. Statistical tests on these eight fields are compared for separate large geographical areas. Critical IR temperature values are then determined as an outcome, which may be valuable when implementing a LI prediction algorithm into real–time satellite–based systems. The presentation will include information on how the results can be applied in a real-time LI system appropriate for increasing lead-time awareness for airport ground operations.