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Comparing a spherical harmonic model of the global electric field distribution with Astrid-2 observations
KTH, Superseded Departments, Alfvén Laboratory.
KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
2002 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 107, no A11Article in journal (Refereed) Published
Abstract [en]

[1] Electric field measurements provided by the double probe instrument on the Astrid-2 satellite are compared with the empirical Weimer electric field model for all magnetic local times, except between 11 and 13 MLT, and poleward of 55degrees corrected geomagnetic latitude (CGLat). We focus the model evaluation on its ability to predict the latitudinal locations of the convection reversal boundaries for two-cell convection patterns and to estimate the magnitude of the electric field above 55degrees CGLat. A total number of 780 polar cap passes are employed from the Northern Hemisphere between January and July 1999. The measured average electric field magnitude in the dawn-dusk meridian plane above 55degrees CGLat is generally 25% larger than the predicted field independent of the interplanetary magnetic field (IMF) direction. The model shows a better correspondence with the observed electric field for southward IMF than for northward IMF, with most cases centered around B-z = -1.5 nT and r = 0.88. However, the agreement for northward IMF is promising, and a few examples are shown to corroborate this fact. The observed and predicted convection reversal boundary locations along the satellite track for southward IMF are on the average found 2-3degrees CGLat apart in the dawn-dusk meridian plane but may be as far apart as 9degrees CGLat. An initial investigation of the relative timing of a 20-min averaging window for the IMF along the 20-25 min polar cap crossing suggests that a time-dependent transfer function may be found that applies a higher weight to the input solar wind data early in the pass and a lower weight later in the pass for an IMF window that corresponds to the first half of the crossing and the opposite weight versus time dependence for an IMF window corresponding to the last half of the crossing.

Place, publisher, year, edition, pages
2002. Vol. 107, no A11
Keyword [en]
global electric field modeling, ionospheric convection, interplanetary magnetic-field, ionospheric convection, mhd model, imf, potentials, patterns
National Category
Fusion, Plasma and Space Physics
URN: urn:nbn:se:kth:diva-22172DOI: 10.1029/2002ja009313ISI: 000180360500058OAI: diva2:340870
QC 20100525 NR 20140804Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2012-03-19Bibliographically approved

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