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| Titel |
Spatial dependence of magnetopause energy transfer: Cluster measurements verifying global simulations |
| VerfasserIn |
M. Palmroth, T. V. Laitinen, C. R. Anekallu, T. I. Pulkkinen, M. Dunlop, E. A. Lucek, I. Dandouras |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 29, no. 5 ; Nr. 29, no. 5 (2011-05-13), S.823-838 |
| Datensatznummer |
250017017
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| Publikation (Nr.) |
 copernicus.org/angeo-29-823-2011.pdf |
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| Zusammenfassung |
| We investigate the spatial variation of magnetopause energy conversion and
transfer using Cluster spacecraft observations of two magnetopause crossing
events as well as using a global magnetohydrodynamic (MHD) simulation
GUMICS-4. These two events, (16 January 2001, and 26 January 2001) are similar in
all other aspects except for the sign of the interplanetary magnetic field
(IMF) y-component that has earlier been found to control the spatial
dependence of energy transfer. In simulations of the two events using
observed solar wind parameters as input, we find that the GUMICS-4 energy
transfer agrees with the Cluster observations spatially and is about 30 %
lower in magnitude. According to the simulation, most of the the energy
transfer takes place in the plane of the IMF (as previous modelling results
have suggested), and the locations of the load and generator regions on the
magnetopause are controlled by the IMF orientation. Assuming that the model
results are as well in accordance with the in situ observations also
on other parts of the magnetopause, we are able to pin down the total energy
transfer during the two Cluster magnetopause crossings. Here, we estimate
that the instantaneous total power transferring through the magnetopause
during the two events is at least 1500–2000 GW, agreeing with ε
scaled using the mean magnetopause area in the simulation. Hence the
combination of the simulation results and the Cluster observations indicate
that the ε parameter is probably underestimated by a factor of 2–3. |
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