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Saturation of superstorms and finite compressibility of the magnetosphere: Results of the magnetogram inversion technique and global PPMLR‐MHD model
Author(s) -
Mishin V. V.,
Mishin V. M.,
Karavaev Yu.,
Han J. P.,
Wang C.
Publication year - 2016
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 - 10.1002/2016gl069649
Subject(s) - magnetosphere , magnetogram , physics , magnetohydrodynamics , solar wind , interplanetary spaceflight , poynting vector , geophysics , saturation (graph theory) , interplanetary magnetic field , magnetopause , computational physics , magnetic field , magnetic flux , mathematics , quantum mechanics , combinatorics
We report on novel features of the saturation process of the polar cap magnetic flux and Poynting flux into the magnetosphere from the solar wind during three superstorms. In addition to the well‐known effect of the interplanetary electric ( E sw ) and southward magnetic (interplanetary magnetic field (IMF) B z ) fields, we found that the saturation depends also on the solar wind ram pressure P d . By means of the magnetogram inversion technique and a global MHD numerical model Piecewise Parabolic Method with a Lagrangian Remap, we explore the dependence of the magnetopause standoff distance on ram pressure and the southward IMF. Unlike earlier studies, in the considered superstorms both P d and B z achieve extreme values. As a result, we show that the compression rate of the dayside magnetosphere decreases with increasing P d and the southward B z , approaching very small values for extreme P d ≥ 15 nPa and B z ≤ −40 nT. This dependence suggests that finite compressibility of the magnetosphere controls saturation of superstorms.