SM14C-09
Experimental observations of electron precipitation driven by EMIC waves
Monday, 14 December 2015: 17:36
2018 (Moscone West)
Craig J Rodger1, Aaron Hendry1, Mark A. Clilverd2, Craig Kletzing3, Mark J. Engebretson4, Geoffrey D Reeves5, James B Brundell1,6 and Marc Lessard7, (1)University of Otago, Dunedin, New Zealand, (2)British Antarctic Survey, Cambridge, United Kingdom, (3)University of Iowa, Iowa City, IA, United States, (4)Augsburg College, Minneapolis, MN, United States, (5)Los Alamos National Laboratory, Los Alamos, NM, United States, (6)ULTRA MSK, Dunedin, New Zealand, (7)University of New Hampshire Main Campus, Durham, NH, United States
Abstract:
It has long been recognised that EMIC waves should be able to pitch angle scatter energetic electrons from the radiation belts, causing them to be lost into the polar atmosphere. However, there has been rather limited experimental evidence demonstrating these losses are taking place. In particular, there has been significant uncertainty regarding the minimum electron energy likely to be affected, and thus the significance of EMIC-losses to the dynamics of the outer radiation belt. We combine observations from multiple space and ground-based experiments to demonstrate EMIC waves are causing precipitation of relativistic electrons. We use POES MEPED data and the AARDDVARK subionospheric network to characterise the electron precipitation. EMIC wave activity is confirmed by the search coil magnetometer in Halley, Antarctica. We also use case studies from the Van Allen Probes to identify the impact of EMIC waves on the evolution of the trapped fluxes. Our study specifically examines the minimum energy of the electron precipitation in these events. These are considerably lower than the relativistic or ultra relativistic levels often predicted by theory, with values commonly as small as a few hundred keV.
