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Ann. Geophys., 24, 3467-3480, 2006
www.ann-geophys.net/24/3467/2006/
© European Geosciences Union 2006
Magnetopause energy and mass transfer: results from a global MHD simulation
M. Palmroth, T. V. Laitinen, and T. I. Pulkkinen
Finnish Meteorological Institute, Space Research Division, Helsinki, Finland
Abstract. We use the global MHD model GUMICS-4 to investigate the energy and mass
transfer through the magnetopause and towards the closed magnetic field as a
response to the interplanetary magnetic field (IMF) clock angle θ=arctan (BY/BZ), IMF magnitude, and solar wind dynamic pressure. We find
that the mass and energy transfer at the magnetopause are different both in
spatial characteristics and in response to changes in the solar wind
parameters. The energy transfer follows best the sin2 (θ/2)
dependence, although there is more energy transfer after large energy input,
and the reconnection line follows the IMF rotation with a delay. There is no
clear clock angle dependence in the net mass transfer through the
magnetopause, but the mass transfer through the dayside magnetopause and
towards the closed field occurs preferably for northward IMF. The energy
transfer occurs through areas at the magnetopause that are perpendicular to
the subsolar reconnection line. In contrast, the mass transfer occurs
consistently along the reconnection line, both through the magnetopause and
towards the closed field. Both the energy and mass transfer are enhanced in
response to increased solar wind dynamic pressure, while increasing the IMF
magnitude does not affect the transfer quantities as much.
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