Global Survey of Whistler Mode Waves in the Earth's Magnetosheath Using THEMIS Observations

Abstract While it is known that whistler mode emissions are frequently detected in Earth's magnetosheath, their properties and dependence on solar wind conditions are not fully understood yet. In this study, we present the global distribution of whistler mode waves in the magnetosheath and their dependence on solar wind parameters, based on 7 years of data from three Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes. Our findings reveal that whistler mode waves in magnetosheath peak near noon, spanning from 9 to 15 magnetic local times, with amplitudes reaching up to 100 pT. Furthermore, whistler mode wave amplitudes and occurrence rates are slightly larger on the dawnside than duskside. Additionally, whistler mode wave amplitudes tend to increase with increasing solar wind dynamic pressure and cone angle. These results provide valuable insights into the plasma and wave environment right upstream of Earth's magnetopause under various solar wind conditions.