Observations directly linking relativistic electron microbursts to whistler mode chorus: Van Allen Probes and FIREBIRD II

Breneman, Aaron

Observations directly linking relativistic electron microbursts to whistler mode chorus: Van Allen Probes and FIREBIRD II

Wednesday, 7 March 2018: 09:10

Longshot and Bogey (Hotel Quinta da Marinha)

Aaron W Breneman¹, Alexander B Crew², David M Klumpar³, Arlo Johnson³, Oleksiy V Agapitov⁴, Mykhaylo Shumko³, Drew L Turner⁵, Ondrej Santolik⁶, John R Wygant⁷, Cynthia A Cattell⁷, Scott A Thaller⁷, J Bernard Blake⁸, Harlan E. Spence⁹, Craig Kletzing¹⁰ and John Glen Sample¹¹, (1)The University of Minnesota, Minneapolis, MN, United States, (2)Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (3)Montana State University, Bozeman, MT, United States, (4)Space Science Laboratory, UCB, Berkeley, CA, United States, (5)The Aerospace Corporation, El Segundo, CA, United States, (6)Academy of Sciences of the Czech Republic, Institute of Atmospheric Physics, Prague, Czech Republic, (7)University of Minnesota, School of Physics and Astronomy, Minneapolis, MN, United States, (8)Aerospace Corporation, Los Angeles, CA, United States, (9)Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moffett Field, CA, United States, (10)University of Iowa, Department of Physics and Astronomy, Iowa City, IA, United States, (11)Montana State University, Physics, Bozeman, MT, United States

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Abstract:

We present observations that provide the strongest evidence yet that discrete whistler mode chorus packets cause relativistic electron microbursts. On Jan 20th, 2016 near 1944 UT the low Earth orbiting CubeSat FIREBIRD II observed energetic microbursts
(near L=5.6 and MLT=10.5) from its lower limit of 220 keV, to 1 MeV. In the outer radiation belt and magnetically conjugate, Van Allen Probe A observed rising-tone, lower band chorus waves with durations and cadences similar to the microbursts. No other waves were observed.
This is the first time that chorus and microbursts have been simultaneously observed with a separation smaller than a chorus packet. A majority of the microbursts do not have the energy dispersion expected for trapped electrons bouncing between mirror points. This confirms that the electrons are rapidly (nonlinearly) scattered into the loss cone by a coherent interaction with the large amplitude (up to ~900 pT) chorus. Comparison of observed time-averaged microburst flux and estimated total electron drift shell content at L=5.6 indicate that microbursts may represent a significant source of energetic electron loss in the outer radiation belt.