Honors Theses and Capstones

Date of Award

Spring 2020

Project Type

Senior Thesis

College or School

CEPS

Department

Physics

Program or Major

Physics

Degree Name

Bachelor of Science

First Advisor

Chia-Lin Huang

Second Advisor

Katharine Duderstadt

Third Advisor

Shawna Hollen

Abstract

The spatial and temporal distribution of high energy electron precipitation from the Van Allen radiation belts is not currently well-understood. The FIREBIRD-II mission (2015-present) and the Van Allen Probes (2012-2019) provide a unique opportunity to examine the behaviors and drivers of high energy electron precipitation. This study quantifies electron precipitation observed by FIREBIRD-II as a function of radial distance (L-shell), magnetic local time (MLT), hemisphere, and geomagnetic indices (Kp). Electron precipitation was observed to peak at L-shell 4.5-5. Regions of elevated electron precipitation were identified at L-shell 4-6 at dawn (MLT 6-9) and dusk (MLT 15-21). Hemisphere filtering indicated very distinct regions of increased precipitation at late dawn and early dusk at L-shell 4-6 in the Northern Hemisphere, while the Southern Hemisphere showed more overall activity as well as increased activity at early dawn and late dusk. Precipitation at high Kp indices (Kp >= 4) displayed elevated activity at all local times. In addition, multiple studies have proposed electromagnetic ion cyclotron (EMIC) waves as a potential driver of electron precipitation. This work searches for connections between EMIC waves observed by the Van Allen Probes and electron precipitation observed by FIREBIRD-II. During times of observed EMIC activity by the Van Allen Probes the FIREBIRD-II satellites recorded increased precipitation during MLT 0-3, MLT 6-9, and MLT 12-18, with activity being especially notable at MLT 15-18. Electron precipitation in the afternoon sector corresponds well with elevated EMIC wave occurrence rates reported in a previous study [Saikin et al., 2015].

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