Abstract
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.
Highlights
Understanding and quantifying the energy and mass transfer from the solar wind to the magnetosphere has been one of the the important long-standing question in space physics.While observationally the question is difficult to solve globally, the behavior of the various activity indices have suggested that the southward orientation of the interplanetary magnetic field (IMF) has a dominant role in the energy transfer (e.g., Burton et al, 1975; Akasofu, 1981)
As the clock angle was the only variable that changed during the course of the runs, four runs were needed to investigate the influence of the two values of IMF magnitude and solar wind dynamic pressure pdyn
The energy transfer occurs through areas at the magnetopause that are perpendicular to the reconnection line
Summary
Understanding and quantifying the energy and mass transfer from the solar wind to the magnetosphere has been one of the the important long-standing question in space physics. Using a test particle approach utilizing the electromagnetic fields from a global MHD simulation, Li et al (2005) reported that lobe reconnection during northward IMF captures magnetosheath plasma, which sinks into the plasma sheet while convecting tailward Using another global MHD code, Palmroth et al (2003) found that electromagnetic energy focusses towards the magnetopause controlling the energy transfer both spatially and temporally, while they did not investigate the spatial extent of mass transfer. We continue the work of Palmroth et al (2003) to fully characterize the energy transfer from the solar wind into the magnetosphere, and for the first time attempt to quantify the mass transfer through the magnetopause and towards the closed field using a global MHD simulation. We end the paper with our discussion and conclusions
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