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Orientation and motion of current layers: minimization of the Faraday residue
Author(s) -
Khrabrov Alexander V.,
Sonnerup Bengt U. Ö.
Publication year - 1998
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 - 10.1029/98gl51784
Subject(s) - spacecraft , magnetopause , traverse , minification , physics , orientation (vector space) , computational physics , computation , algorithm , faraday effect , geophysics , statistical physics , computer science , geodesy , magnetosphere , geometry , magnetic field , mathematics , mathematical optimization , geology , quantum mechanics , astronomy
A simple analytical solution is presented for a minimization problem encountered by Terasawa et al. [1996] in analyzing electromagnetic (EM) field and plasma data series acquired by a spacecraft traversing a one‐dimensional (1D) current layer. Their analysis was developed to infer the direction of spatial variation, n, and velocity, u n , along n of a 1D EM structure such as the bowshock, the magnetopause, or the geotail current sheet. We show that the optimization procedure of Terasawa et al., which involved a numerical search, in fact reduces to solving a 3 × 3 eigen‐problem for a certain matrix Q defined in terms of the data. A step‐by‐step outline is given of the operations needed to predict n and u n in this manner from an actual data set. Statistical estimates of uncertainty are given. Two magnetopause crossings by the spacecraft AMPTE/IRM are used to illustrate the procedure and to compare the results with those obtained by other methods.