Wave-particle interactions in the exterior cusp region and in the nearby magnetosheath

0446633 - ÚFA 2016 CZ eng A - Abstract
Grison, Benjamin - Escoubet, C. P. - Santolík, Ondřej - Lavraud, B. - Cornilleau-Wehrlin, N.
Wave-particle interactions in the exterior cusp region and in the nearby magnetosheath.
26th IUGG General Assembly 2015. Earth and Environmental Sciences for Future Generations : abstracts. Prague: International Union of Geodesy and Geophysics, 2015. A33p-007.
[Earth and Environmental Sciences for Future Generations. General Assembly of International Union of Geodesy and Geophysics /26./. 22.06.2015-02.07.2015, Prague]
Institutional support: RVO:68378289
Keywords : magnetospheric physics * space plasma physics * wave-particle interaction
Subject RIV: DG - Athmosphere Sciences, Meteorology
http://www.iugg2015prague.com/abstractcd/data/HtmlApp/main.html#

In the early years (2000-2004) of the mission, Cluster crossed the most distant part of the polar cusps. On 05/01/2002, Cluster enters the distant cusp region on the duskside of the southern hemisphere (inbound). The spacecraft are successively crossing the magnetopause between 19:50 UT (SC4) and 20:15 UT (SC3). The interplanetary conditions during the crossing were stable with a dominant negative IMF-By. The magnetometer (FGM) data indicates that the entry into the cusp takes place in a region where the magnetic field lines in the magnetosheath are anti-parallel to the field lines in the magnetosphere. Despite this clear picture, the global encounter is rather complex: one can notice partial magnetopause crossings, magnetic null points, and intense monochromatic waves on both sides of the magnetopause. We investigate the ULF waves observed in the cusp and in the nearby magnetosheath, just before the magnetopause crossing by the spacecraft. Left-handed monochromatic waves observed in the cusp display different duration and frequency (below and above the local proton gyrofrequency) on each spacecraft. Both the Poynting flux of these emissions and the simultaneously recorded ion flows propagate in the same direction - toward the Earth. The wavenumber are determined in two ways: using the Doppler shift and from direct measurements of the refractive index. We use the ion particle distribution functions and the ion moments (density, velocity and temperature) to explain the wave generation process. The role of the proton temperature anisotropy, proton shell distributions and velocity shears are investigated.
Permanent Link: http://hdl.handle.net/11104/0248926