SM13F-4219:
Cluster Observations of Particle Injections in the Exterior Cusp
Monday, 15 December 2014
C Philippe Escoubet1, Benjamin Grison2, Jean Berchem3, Karlheinz J Trattner4, Benoit Lavraud5, Frederic Pitout6, Jan Soucek7, Robert L Richard8, Harri E Laakso9, Arnaud Masson10, Malcolm Wray Dunlop11, Iannis Dandouras12, Henri Reme5, Andrew Neil Fazakerley13 and Patrick W Daly14, (1)ESTEC, Noordwijk, 2201, Netherlands, (2)IAP, Prague 4, Czech Republic, (3)UCLA IGPP, Los Angeles, CA, United States, (4)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (5)IRAP, Toulouse, France, (6)Twin Falls School District, Toulouse, France, (7)Academy of Sciences of the Czech Republic, Prague, 182, Czech Republic, (8)UCLA, Los Angeles, CA, United States, (9)ESTEC, Noordwijk, Netherlands, (10)European Space Agency, Villanueva De La Can, Spain, (11)Science and Technology Facilities Council, Didcot, United Kingdom, (12)IRAP, Toulouse, Italy, (13)University College London, London, United Kingdom, (14)Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
Abstract:
The main process that injects solar wind plasma into the polar cusp is now generally accepted to be magnetic reconnection. Depending on the IMF direction, this process takes place equatorward (for IMF southward), poleward (for IMF northward) or on the dusk or dawn sides (for IMF azimuthal) of the cusp. We report a Cluster crossing on 5 January 2002 near the exterior cusp on the southern dusk side. The IMF was mainly azimuthal (IMF-By around -5 nT), the solar wind speed lower than usual around 280 km/s with the density of order 5 cm-3. The four Cluster spacecraft had an elongated configuration near the magnetopause. C4 was the first spacecraft to enter the cusp around 19:52:04 UT, followed by C2 at 19:52:35 UT, C1 at 19:54:24 UT and C3 at 20:13:15 UT. C4 and C1 observed two ion energy dispersions at 20:10 UT and 20:40 UT and C3 at 20:35 UT and 21:15 UT. Using the time of flight technique on the upgoing and downgoing ions, which leads to energy dispersions, we obtain distances of the ion sources between 14 and 20 RE from the spacecraft. Using Tsyganenko model, we find that these sources are located on the dusk flank, past the terminator. The first injection by C3 is seen at approximately the same time as the 2nd injection on C1 but their sources at the magnetopause were separated by more than 7 RE. This would imply that two distinct sources were active at the same time on the dusk flank of the magnetosphere. In addition, a flow reversal was observed at the magnetopause on C4 which would be an indication that reconnection is taking place near the exterior cusp.
