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On the generation of magnetic dips ahead of advancing dipolarization fronts
Author(s) -
Pan DongXiao,
Zhou XuZhi,
Shi QuanQi,
Liu Jiang,
Angelopoulos Vassilis,
Runov Andrei,
Zong QiuGang,
Fu SuiYan
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl064369
Subject(s) - physics , ion , front (military) , plasma , magnetosphere , azimuth , computational physics , reflection (computer programming) , population , diamagnetism , geophysics , atomic physics , astrophysics , magnetic field , optics , nuclear physics , meteorology , quantum mechanics , demography , sociology , computer science , programming language
Dipolarizing flux bundles transport magnetic flux to the inner and dayside magnetosphere, heat the plasma sheet, and provide a seed population to the radiation belt. The magnetic perturbation ahead of them, often referred to as a dipolarization front (DF), is asymmetric with a small B z dip followed by a sharp B z enhancement. The B z dip is thought to be generated from dawnward currents carried by DF‐reflected ions; after reflection, these earthward moving ions gyrate clockwise and contribute to dawnward diamagnetic currents ahead of the front. Using observations of hundreds of DFs, we investigate this hypothesis. We find that the depth of the B z dip as a function of the front azimuth depends on DF propagation speed and ambient plasma density. These statistical signatures support the hypothesis that the B z dip is caused by ion reflection and suggest that secondary currents carried by these reflected ions can reshape the front significantly.