Fennell, J.F.,
Co-Authors: J. Roeder, B. Blake, A. Korth, M. Carter, P. Daly, R. Friedel, T. Fritz, M. Grande, and C. Perry.,
Title: Joint Cluster and Polar study of the dayside magnetospheric boundaries.,
Reference: European Geophysical Society meeting. Nice, April 2002.
Reference Type: Contributed Talk
CEPPAD: false
CAMMICE: true
RAPID: true
Abstract:
The Cluster and Polar spacecraft have their apogees close in local time and in April 2001 these spacecraft were traversing the pre-noon magnetosphere. Polar’s apogee was at about 25 deg. magnetic latitude and it traversed the mid-altitude polar cusp/cleft, LLBL, dayside plasma sheet and sometimes entered the magnetosheath and even the solar wind when near apogee during active periods. The Cluster satellites traversed the mid to high-latitude plasma sheet, cusp/cleft, LLBL, magnetosheath, bow shock and spent extended periods in the solar wind upstream of the bow shock in the pre-noon sector. There were several intervals where the Cluster and Polar satellites were in the same regions simultaneously. One particular example occurred on 13 April 2001 in the 0400-1200 UT during the recovery of a magnetic storm. An interplanetary shock was observed at L1 near 0705 UT and reached Earth near 0735 UT on this day. The Cluster RAPID energetic particle experiment observed enhanced energetic ion fluxes starting more than two hours prior to the arrival of the shock. During this time, Polar was traversing the nominal southern and northern dayside plasma sheet, heading towards apogee. At the initial shock arrival, the solar wind pressure increased by a factor of three and the solar wind speed increased from 590 to 760 km/sec, but Polar stayed inside the plasma sheet. Near 0935 UT the solar wind density and pressure rose by an order of magnitude and Polar passed from the plasma sheet into a magnetosheath like plasma. As the event continued, Polar passed into the solar wind. During this interval the Cluster satellites observed a very intense and ! hot solar wind population and the interplanetary field turned strongly southward. Polar reentered the magnetosheath like plasma again near 1100 UT as the IMF turned northward. Polar experienced a second short transition into the solar wind near 1250 UT, and returned into a magnetosheath-like plasma for the next few hours. While in the solar wind, Polar observed transitory fluxes of very energetic ions which may be bow-shock associated or leakage from the compressed magnetosphere. We will discuss the combined Polar-Cluster observations during this event with some focus on the source of the energetic ions observed upstream of the bow shock.
