Data from Satellites and Researchers
The database covers the dayside, flanks and nightside, including the deep tail, and spans the time range 1963 - 1998.
||Fairfield, Crooker, Paschman, Haerendel|
|IMP 1, IMP 2, IMP 3,|
|IMP 6||Eastman, Lui|
|IMP 8||Lui, Davis, Sibeck|
|HEOS 2||Crooker, Paschman, Haerendel|
|ISEE 1, ISEE 2||Rijnbeck, Eastman|
|Prognoz 7, Prognoz 8, Prognoz 10||Zastenker|
|AMPTE IRM||No source given|
|Geotail (deep tail)||Eastman, Christon, Hasegawa|
General SELECTION CRITERIA
The most reliable identifications of magnetopause crossings are made with a combination of 3D magnetic field measurements, suprathermal and energetic ions and electrons. There is a clear change in average magnetic field orientation between the magnetosheath and the boundary layer / magnetosphere. The number of suprathermal particles decreases from magnetosheath to magnetosphere, but the number of energetic particles increases.
More than half of all magnetopause crossings involve multiple crossings because the satellite speed is low (2-4 km/s) whereas boundary motions can range from less than 5 to more than 50 km/s.
Specific SELECTION CRITERIA
Fairfield identified crossings
Crossings were identified from magnetometer data using field magnitudes, direction changes and RMS values [Fairfield, J. Geophys. Res., 1971]. Only one crossing per pass was determined with the "average position" selected by visually determining the point that equalized the magnetosphere time outside the point with the magnetosheath time inside the point.
Eastman identified crossings
Crossings were identified by a distinct magnetic field shift from the nearby average magnetosheath orientation to an orientation more closely aligned with outer magnetosphere values characteristic for the crossing location (noting that boundary layer plasmas and field stresses near the boundary cause distortions to the geomagnetic field near the outer boundary).
Hasegawa identified crossings
Crossings were identified using both plasma and magnetic field data, paying special attention to rotation of the magnetic field. For some cases when identification was difficult, ion energy-time spectrograms were also used.
Davis and Sibeck identified crossings
Crossings were identified using magnetic field orientation changes and minimum variance. Each crossing was separately identified.
What is the magnetopause?
As the supersonic solar wind flow approaches the Earth and its geomagnetic field, the solar wind plasma (ions and electrons) envelopes and confines the geomagnetic field. The outer boundary of the confined geomagnetic field is called the "magnetopause."
Just inside the magnetopause frequently there is a boundary layer composed of transitional plasma, between magnetosheath (outer) and magnetosphere (inner) values.
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