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Characteristics of high‐latitude precursor flows ahead of dipolarization fronts
Author(s) -
Li JiaZheng,
Zhou XuZhi,
Runov Andrei,
Angelopoulos Vassilis,
Liu Jiang,
Pan DongXiao,
Zong QiuGang
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2017ja023902
Subject(s) - plasma sheet , physics , plasma , flux (metallurgy) , kinetic energy , latitude , geophysics , particle (ecology) , ion , current sheet , computational physics , atmospheric sciences , magnetohydrodynamics , geology , magnetosphere , classical mechanics , materials science , astronomy , nuclear physics , quantum mechanics , metallurgy , oceanography
Dipolarization fronts (DFs), earthward propagating structures in the magnetotail current sheet characterized by sharp enhancements of northward magnetic field, are capable of converting electromagnetic energy into particle kinetic energy. The ions previously accelerated and reflected at the DFs can contribute to plasma flows ahead of the fronts, which have been identified as DF precursor flows in both the near‐equatorial plasma sheet and far from it, near the plasma sheet boundary. Using observations from the THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft, we show that the earthward particle and energy flux enhancements ahead of DFs are statistically larger farther away from the neutral sheet (at high latitudes) than in the near‐equatorial region. High‐latitude particle and energy fluxes on the DF dawnside are found to be significantly greater than those on the duskside, which is opposite to the dawn‐dusk asymmetries previously found near the equatorial region. Using forward and backward tracing test‐particle simulations, we then explain and reproduce the observed latitude‐dependent characteristics of DF precursor flows, providing a better understanding of ion dynamics associated with dipolarization fronts.