A new link between El Nino-Southern Oscillation and atmospheric electricity

The global electric circuit (GEC) is a unique atmospheric system driven by the global distribution of thunderstorms and electrified shower clouds. The GEC unites electric fields and currents in the entire atmosphere and is characterized by the permanent production and dissipation of huge amounts of electrical energy. In this study, aimed at investigating the links between the GEC and El Nino-Southern Oscillation (ENSO), the GEC variability during 2008-2018 is simulated on the basis of reanalysis meteorological data using the Weather Research and Forecasting model and a parameterization of the ionospheric potential (IP), which is a natural measure of the GEC intensity. Modelling shows that strong El Nino and La Nina events influence the global distribution of electrified clouds over the Earth's surface, thereby consistently affecting the shape of the diurnal variation of the GEC. Further analysis shows that anomalies in the Nino 3.4 sea surface temperature, which characterize the ENSO phase, and anomalies in the relative IP are positively correlated at 9:00-15:00 UTC and negatively correlated at 18:00-23:00 UTC. This correspondence between ENSO and the GEC is most prominent at 13:00 UTC and 21:00 UTC, and most pronounced anomalies in the relative IP around these hours are precisely associated with strong El Nino and La Nina events. In particular, during strong El Ninos the relative IP is larger than usual around 13:00 UTC and smaller than usual around 21:00 UTC, whereas during strong La Ninas it behaves oppositely.