Magnetosheath Jet-Triggered ULF Waves: Energy Deposition in the Ionosphere

Abstract

Magnetosheath jets, transient plasma structures of enhanced dynamic pressure, have been observed to trigger ultra-low frequency (ULF) waves in the magnetosphere. These ULF waves contribute to energy transport in the magnetosphere-ionosphere system. Therefore, there is a need to estimate the energy input into the ionosphere due to jet-triggered ULF waves. In this study, we combine measurements from Magnetospheric Multiscale, ground-based magnetometers, the EISCAT radar on Svalbard, and SuperDARN to estimate the Joule heating in the ionosphere resulting from jet impacts at the magnetopause. Focusing on three jets observed on 2016-01-07 we were able to calculate the Joule heating for two jets. We found an average Joule heating rate of $0.38$ mW/m² which is on par with other processes such as field line resonances. However, due to the short duration and spatial confinement of the jet-induced ULF waves, the average energy input was only $9\cdot 10^{10}$ J. This suggests that the energy deposition of jet-triggered ULF waves is small compared to other magnetospheric processes, and thus does not significantly impact the average energy budget of the magnetosphere.