GEM: Characteristics of Electron Cyclotron Harmonic Waves in the Earth's Magnetosphere

University Of Texas At Dallas, Richardson TX

Investigators

Abstract

This project aims to investigate a newly reported wave mode that interacts with energetic electrons in the Earth’s magnetosphere, potentially driving their precipitation into the atmosphere to aurora activity. This work will explore the excitation mechanism and favored magnetospheric conditions of the Electron Cyclotron Harmonic (ECH) waves and their effects on electron precipitation at the dayside under different geomagnetic conditions. This work will provide knowledge and predictive capabilities of the energetic charged particles in space, which pose a hazard to the space assets that modern society relies on and contribute to the Nation’s security and welfare. The project provides training and support for a new graduate student. The primary objective of the effort is to advance our understanding of excitation, global distribution, and scattering effect on electrons of magnetospheric ECH waves, especially at the dayside. These emissions are believed to be excited by the loss-cone instability of plasma sheet electrons and have been demonstrated to cause energetic electron precipitations that lead to diffuse and pulsating auroras. Recent observations show significant occurrences of ECH waves on the dayside magnetosphere at large L-shell, which provides a great hint of a secondary source region of ECH waves at the dayside. The team will investigate the excitation mechanism and favored magnetospheric conditions of the newly reported dayside ECH waves and their effects in the Geospace environment, which remain open questions. The team will address the following science questions: SQ1) What are the preferred conditions for dayside ECH wave excitation? SQ2) Statistically, is there a secondary source region of ECH waves on the dayside magnetosphere? SQ3) How do those dayside ECH waves affect electron precipitation? The methodology includes (1) analysis of ECH waves and electron data from MMS, Van Allen Probes, THEMIS, and Cluster, (2) instability analysis to examine the ECH wave excitation, and (3) quasi-linear diffusion theory to examine the physical link between the ECH waves and electron precipitation using conjugation with DMSP observation. Understanding the ECH wave excitation, distribution, and their effect on energetic electron scattering in the magnetosphere will improve the understanding of the ring current and radiation belt dynamics and predict the energetic particle environment. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.