A Comparison of Satellite-Based Radar and Passive Microwave Estimates of Global Wilson Current Source

Abstract:

A passive microwave algorithm for estimating the electrical footprint of charged clouds has been developed and applied to satellite observations taken by the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), which has a domain spanning the entire tropics up to 36 degrees latitude, and compared with lightning-based estimates of global electricity and the Carnegie curve. While these results show considerable agreement with historical observations for convective storms, this method has difficulty characterizing electricity in stratiform clouds and storms at different stages of the convective lifecycle. The algorithm also does not take advantage of the full suite of observations available in the 16-year TRMM dataset, which also includes Precipitation Radar (PR) observations of the structure of storms overflown by the satellite. As a first step towards building an algorithm that can characterize electrical input to the Global Electric Circuit (GEC) from a wide variety of storms across the globe, this study compares passive microwave-based approximations of global electricity with precipitation radar-based approximations in order to determine the relative skill each platform has in describing the “battery” of the GEC and to identify a possible pathway towards a combined metric that can use the strengths of both instruments to better describe electrified clouds.