Relating Electrified Cloud Properties to Wilson Currents: an Oceanic and Continental Case Study

Thunderstorms and other electrified, non-lightning producing clouds are thought to play an important role in maintaining the potential difference between Earth's surface and upper atmosphere. These clouds are responsible for producing Wilson currents between cloud tops in the troposphere and the electrosphere which help sustain the Global Electric Circuit (GEC). Estimates of Wilson currents for oceanic and continental electrified clouds were recently derived from data collected over two decades during multiple field campaigns involving the NASA ER-2 aircraft. It was found that the strength of Wilson currents varies by storm type and, on average, is higher for oceanic storms than their continental counterparts. This study builds upon findings made from the ER-2 data set and investigates relationships between the dynamical and microphysical properties of electrified clouds alongside their ER-2 Wilson current estimates. Variations of these properties were also studied during the lifecycles of one oceanic and two continental storms from 19 September 2001. Maximum reflectivity measured by the Next Generation Radar (NEXRAD) and ER-2 Doppler radars, along with radar derived precipitation ice mass and ice water path, updraft volume, maximum updraft velocity and echo top height were compared to the Wilson current estimates. Some cloud properties, such as ice water path and updraft volume, correlated well to the Wilson currents. Cloud top heights, however, did not have such a strong correlation. Further research is needed to determine if these results are robust. If proven, they could be utilized as Wilson current parameterizations in a modeling framework of the GEC.