Lightning Correlation with Environmental Variables Using the TRMM LIS

Societal and environmental impacts of lightning are experienced globally, from forest fires to the modification of the NOx cycle. Lightning is known to occur in intense thunderstorms that are expected to exhibit higher values of convective available potential energy (CAPE), column saturation fraction (r), and vertical velocity (omega). We seek to better understand these environmental variables that previous studies have identified as the most relevant in relation to lightning occurrences.

Lightning flash counts and rates across the global tropics are obtained using the Tropical Rainfall Measuring Mission’s (TRMM) Lightning Imaging Sensor (LIS), and then compared to observational data from the 3-hourly MERRA2 Reanalysis for the period between 1997 and 2015. CAPE calculations will vary based off the estimation of the lifting condensation level (LCL) and the correlation of lightning frequency with r and omega will be considered at multiple different levels within the atmosphere. Using a variety of methods for calculation will provide further analysis to the data in order to detect which method provides the best results. The lightning data and the reanalysis data will be gridded with three different grid spacings, which will also provide a more in-depth analysis. Land vs ocean correlation will be thoroughly studied to diagnose different relationships between the lightning data and its environmental variables. For example, preliminary results show that almost all lightning over land occurs at high r (between 0.8 and 0.9), while over the ocean, no diagnosed pattern of r vs flash counts is present yet. The correlation of TRMM lightning data and CAPE, r, and omega will give insight to what conditions are the best predictors of lightning events.