Open AccessDawnside magnetopause observed by the Equator‐S Magnetic Field Experiment: Identification and survey of crossings
Author(s) -
Dunlop M. W.,
Balogh A.,
Baumjohann W.,
Haerendel G.,
Fornacon K.H.,
Georgescu E.
Publication year - 1999
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999ja900214
Subject(s) - magnetosheath , magnetopause , solar wind , geophysics , equator , physics , latitude , geology , astrophysics , geodesy , magnetic field , computational physics , astronomy , quantum mechanics
The German Equator‐S spacecraft provided long‐duration, low‐latitude coverage of the dawnside magnetopause and adjacent magnetosheath. We document 131 magnetopause crossings from 31 orbits, giving coverage from 0600 to 1040 LT and exhibiting a wide range of local magnetic shear. The Tsyganenko model field is used routinely to assist identification and in categorizing the crossings. The apogee of the spacecraft remains close to the magnetopause for mean solar wind pressure. Consequently, magnetosheath intervals often extending several hours are observed, many containing a high number of crossings. For most encounters, a well‐ordered, tangential (draped) magnetosheath field is observed; 30% containing extended intervals of strong mirror signatures. The occurrence of the crossings is summarized, and locations are found to compare well to predicted boundary positions using observed, upstream solar wind IMF and pressure values; some corresponding to unusually high solar wind ram pressure. Other crossing characteristics have also been analyzed, such as boundary normals. Although these are broadly consistent with fitted, model magnetopause orientations, they typically lie sunward of these, suggesting a blunter magnetopause shape in this region than predicated. No strong evidence is found of large deviations in local boundary orientations, possibly consistent with the highly draped magnetosheath field configuration.