GEM: The Competition Between Waves and Field Line Scattering in Driving Relativistic Electron Precipitation and the Resulting Atmospheric Effects

Electron precipitation into the Earth’s atmosphere is typically driven by plasma waves excited in the magnetosphere or by scattering due to the curvature of magnetic field lines (also known as current sheet scattering, CSS). As a result, the radiation space environment can undergo a significant loss and its energy is directly deposited into the atmosphere. This proposal aims to assess the respective role of waves and field line scattering in the relativistic electron precipitation and to evaluate its effects on the Earth’s atmosphere. The PI is an early career female scientist who will be mentored by a female faculty and a senior female scientist. Graduate and undergraduate students will be supported. This project focuses on relativistic electron precipitation (REP) and addresses the following science questions (SQ): SQ1. What are the properties of wave-driven REP compared to CSS-driven REP? SQ2. What is the relative contribution of wave-driven REP and CSS-driven REP to the total REP? SQ3. What are the effects of REP on the atmosphere (e.g., ozone depletion, conductivity change)? This builds on preliminary work showing that the observed precipitation profiles at low-Earth-orbit differ depending on the associated driver. REP events will be collected from a decade of observations, which we will use as inputs to the Whole Atmospheric Community Climate Model (WACCM) to estimate the resulting atmospheric effects. The work will quantify if, where, and under what geomagnetic conditions CSS is more efficient in causing electron precipitation than waves. This result will be useful to radiation belt models that currently do not typically consider CSS. Similarly, the team will obtain the distribution of REP and its contribution from waves. With such information, they will infer the magnetospheric regions where pitch-angle scattering from wave-particle interactions is more favorable for relativistic electrons. Finally, WACCM simulations will provide an estimate of the ozone depletion caused specifically by relativistic electrons in the latitude and longitude where they occur most often, contributing toward how the local REP contribution should be considered in large scale atmospheric models. 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.