Joule Heating in the Northern Hemisphere During Geomagnetic Storms Driven by High‐Speed Streams and Coronal Mass Ejections

Abstract We present a robust method for estimating the auroral Joule heating in the northern hemisphere by combining SuperMAG, SuperDARN and AMPERE data products. This method is applied to 292 storms during 2010–2023. Temporal evolution and spatial distributions of the storm‐time Joule heating are studied using a superposed epoch analysis, with the storms divided into three categories based on the solar wind structures driving the storms' main phase: solar wind high speed streams and associated stream interaction regions (HSS/SIR), or sheath regions and magnetic clouds associated with interplanetary coronal mass ejections (ICME). It is found that the Joule heating has a fast increase at the beginning of the storm main phase when the storm is initiated by HSS/SIRs or by ICME sheath regions, while a more gradual and longer lasting increase is found in storms driven by magnetic clouds within the ICMEs. In all the driver categories the Joule heating during the main phase is concentrated on the morning and afternoon auroral ovals, with the largest hemispheric median heating of just over 240 GW seen at the end of the main phase in storms driven by sheaths and magnetic clouds. Joule heating is highly correlated with the SuperMAG SME index ( values between 0.72 and 0.76), while correlation with the Newell coupling function is moderate ( values between 0.52 and 0.56). Magnetic cloud driven storms have the highest geoefficiency in terms of solar wind energy input driving Joule heating.