A TRMM Assessment of the Composition of the Generator Current That Supplies the Global Electric Circuit

Abstract

AbstractThe Peterson et al. (2015, https://doi.org/10.1175/JTECH-D-14-00119.1) passive microwave electric field retrieval is applied to 15 years of Tropical Rainfall Measuring Mission (TRMM) satellite observations to estimate the amount of Wilson current supplied to the Global Electric Circuit from individual electrified cloud features (ECFs), which are identified as contiguous precipitating cloud regions that produce Wilson current. Current contributions from 37 million ECFs sampled by TRMM are used to examine the composition of the DC generator current. Thunderstorms are found to supply 61% of the total retrieved current, while electrified shower clouds provide the remaining 39%. ECFs over land contribute 38% of the total current, while the ocean contributions are divided between coastal oceanic regions (35%) and the open ocean (27%). The greatest share of the total TRMM‐retrieved current comes large mesoscale features (>2 × 103 km2 in area) and features that have peak 20‐km electric fields in excess of 1 kVm−1. This combination of extent and intensity leads to total currents greater than 10 A for a single ECF. The ranking of the tropical chimney regions by total current production is (1) the Americas (38%), (2) Asia (32%), and (3) Africa (15%). ECFs over the tropical Pacific Ocean contribute the remaining 15%. The Africa chimney is most prominent in total lightning activity but lags behind the others in total DC current due to a reduced frequency of electrified weather and weaker per‐storm electric fields and Wilson currents compared to the other chimneys.