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Looking for Evidence of Wind‐Shear Disconnections of the Earth's Magnetotail: GEOTAIL Measurements and LFM MHD Simulations
Author(s) -
Borovsky Joseph E.
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja025456
Subject(s) - physics , solar wind , substorm , geophysics , magnetosheath , magnetohydrodynamic drive , magnetohydrodynamics , spacecraft , astrophysics , magnetopause , plasma , astronomy , magnetosphere , quantum mechanics
Disconnections of the Earth's magnetotail caused by abrupt wind shear in the solar wind are predicted by global magnetohydrodynamic simulations. Further, analysis of ACE spacecraft measurements finds that strong wind shears in the solar wind at Earth are common. In this report GEOTAIL observations in the distant (~200 R E ) magnetotail are used to look for evidence of these predicted disconnection events. Three‐dimensional global magnetohydrodynamic simulations using the LFM (Lyon‐Fedder‐Mobary) code were run to determine the expected signatures of magnetotail‐disconnection events as seen by a spacecraft. Fourty‐four magnetotail entry events on the dawnside of the distant magnetotail in the years 1993–1994 were examined individually and using superposed‐epoch analysis. Signatures in the GEOTAIL measurements consistent with entry into the magnetotail from the magnetosheath caused by disconnection events were seen, particularly the temporal pattern of plasma flow and the temporal pattern of the magnetic field direction. Conclusive observations of magnetotail disconnections will probably have to await having measurements with a constellation of spacecraft in the magnetotail.