Simultaneous Observation of Magnetopause Expansion Under Radial IMF and Indention by HSJ

Abstract To analyze the influence of high‐speed jets (HSJs) on the position of the magnetopause during long‐term radial interplanetary magnetic fields (IMFs), we report three events of magnetopause expansions and indentions by HSJs observed by Time History of Events and Macroscale Interactions during Substorms. In these events, the upstream solar wind condition is stable and the IMF direction is quasi‐radial, characterized by the cone angle less than 30°. Actually, such upstream conditions are rare, especially when the HSJ is observed near the magnetopause crossing time. The actual positions of the magnetopause in these three cases are further away from Earth than that shown by the empirical models. A local indention in the magnetopause caused by HSJ is inferred by the inward movement of the magnetopause from the compression of HSJ. It is the first time to report the simultaneous magnetopause expansion under radial IMF and magnetopause indention caused by HSJ.