The Shape of Strongly Disturbed Dayside Magnetopause

Abstract

During strong geomagnetic disturbances, the Earth's magnetosphere exhibits unusual and nonlinear interaction with the incident flow of magnetized solar wind plasma. Global Magneto-hydro-dynamic (MHD) modeling of the magnetosphere predicts that the storm-time effects at the magnetopause result from the abnormal plasma transport and/or extremely strong field aligned currents. In-situ observations of the magnetospheric boundary, magnetopause, by Geosynchronous Operational Environmental Satellite (GOES) allowed us to find experimentally such effects as a saturation of the dayside reconnection, unusual bluntness and prominent duskward skewing of the nose magnetopause. The saturation and duskward skewing were attributed to the storm-time magnetopause formation under strong southward interplanetary magnetic field (IMF). The unusual bluntness was observed during both high solar wind pressure and strong southward IMF. We suggest that these phenomena are caused by a substantial contribution of the cross-tail current magnetic field and the hot magnetospheric plasma from the asymmetrical ring current into the pressure balance at the dayside magnetopause.Key words: Magnetopause, Magnetospheric currents, Geomagnetic storm Citation: Dmitriev, A. V. and A. V. Suvorova, 2013: The shape of strongly disturbed dayside magnetopause. Terr. Atmos. Ocean. Sci., 24, 225-232, doi: 10.3319/TAO.2012.09.26.02(SEC)

Polar cap response to the solar wind density jump under constant southward IMF

“…Thus, under the strong southward IMF or during the solar wind dynamic pressure jump, R 1 changes (from ~10 R E for the average quiet condi tions to less than geosynchronous orbit, 6.6 R E , for very disturbed states; here R E = 6378 km is the Earth's radius). Dmitriev and Suvorova (2013) noted that the minimum R 1 is reached at B z ~ -20 nT (E sw ~10 mV m -1 ) and this value growths with P sw . After the pressure pulse encounter, the reconstruction of the main mag netospheric current systems (magnetopause and tail currents) begins.…”

A superposed epoch study of the effects of solar wind stream interface events on the upper mesospheric and lower thermospheric temperature

“…There is a sector reversal from north to south on arrival of SI. A southward interplanetary magnetic field will cause the magnetopause to be pushed inward from its stand-off distance (Dmitriev and Suvorova, 2013). During the southward turning of IMF B z , energetic particles can gain access into the Earth's upper atmosphere due to magnetopause distortion.…”