Response of Thermospheric Neutral Density and Joule Heating to Intense Geomagnetic Storms Driven by Complex Interplanetary Structures

Abstract

We investigate the response of thermospheric neutral density and associated Joule heating (JH) with different interplanetary structures during 73 intense geomagnetic storms. Neutral density is derived from accelerometers onboard CHAMP, GRACE‐A, SWARM‐C, and GRACE‐FO satellites during 2001–2024. We estimate the JH variation using the data from the DMSP spacecraft and the Weimer electric potential model. Four typical interplanetary structures identified as the primary drivers of intense storms (Dst ≤ −100 nT) are analyzed in terms of their influences on neutral density and JH: isolated interplanetary coronal mass ejections (ICMEs) (29% storms), successive ICMEs (44% storms), interacting ICME‐HSS structures (26% storms), and high‐speed streams (HSSs) alone (1% storm). The middle two categories represent the complex interplanetary structures. The results show that neutral density and associated JH were significantly enhanced during the May 2024 superstorm driven by successive ICMEs. The complex interplanetary structures, including successive ICMEs and interacting ICME‐HSS structures, lead to significant and prolonged neutral density enhancements during intense storms, in contrast to isolated ICMEs. During successive ICME‐driven storms, enhanced interplanetary magnetic field and solar wind (SW) are associated with increased JH, which has a strong impact on storm‐time neutral density. The interaction between ICMEs and HSSs causes the same distribution in density intensity as that during isolated ICME‐induced intense storms but substantially extends the duration of density enhancement, plausibly resulting from enhanced SW due to interacting ICME‐HSS structures.