Тип публикации: статья из журнала
Год издания: 2013
Идентификатор DOI: 10.5194/angeo-31-1779-2013
Ключевые слова: Magnetospheric physics, Magnetosheath, Magnetospheric physics (Magnetosheath), coronal mass ejection, magnetic field, magnetosphere, plasma, solar wind
Аннотация: Acceleration of magnetosheath plasma resulting from the draping of the interplanetary magnetic field (IMF) around the magnetosphere can give rise to flow speeds that exceed that of the solar wind (V-SW) by up to similar to 60%. Three case event studies out of 34 identified events are described. We then present a statistical study oПоказать полностьюf draping-related accelerations in the magnetosheath. Further, we compare the results with the recent theory of Erkaev et al. (2011, 2012). We present a methodology to help distinguish draping-related accelerations from those caused by magnetic reconnection. To rule out magnetopause reconnection at low latitudes, we focus mainly on the positive B-z phase during the passage of interplanetary coronal mass ejections (ICMEs), as tabulated in Richardson and Cane (2010) for 1997-2009, and adding other events from 2010. To avoid effects of high-latitude reconnection poleward of the cusp, we also consider spacecraft observations made at low magnetic latitudes. We study the effect of upstream Alfven Mach number (M-A) and magnetic local time (MLT) on the speed ratio V/V-SW. The comparison with theory is good. Namely, (i) flow speed ratios above unity occur behind the dawn-dusk terminator, (ii) those below unity occur on the dayside magnetosheath, and (iii) there is a good general agreement in the dependence of the V ratio on M-A.
Журнал: ANNALES GEOPHYSICAE
Выпуск журнала: Vol. 31, Is. 10
Номера страниц: 1779-1789
ISSN журнала: 09927689
Место издания: GOTTINGEN
Издатель: COPERNICUS GESELLSCHAFT MBH