Simultaneous observations of solar wind plasma entry from FAST and POLAR

W. K. Peterson, Y. -K. Tung, C. W. Carlson, J. H. Clemmons, H. L. Collin, R. E. Ergun, S. A. Fuselier, C. A. Kletzing, D. M. Klumpar, O. W. Lennartsson, R. P. Lepping, N. C. Maynard, J. P. McFadden, T. G. Onsager, W. J. Peria, C. T. Russell, E. G. Shelley, L. Tang, and J. Wygant

Lockheed Martin, 3251 Hanover St., Palo Alto, CA


On November 15, 1996, NASA FAST and POLAR satellites obtained data in the cusp/cleft region for extended intervals. POLAR sampled a narrow range of local times. FAST observed cusp/cleft plasma for more than 5 hours in local time. At 07:51 UT the satellites were in near magnetic conjunction, and the interplanetary magnetic field was steady for an extended interval before this time. We confirm prior observations that show solar wind plasma often enters the magnetosphere over extended regions of local time. For the one hour interval of steady solar wind conditions when POLAR encountered cusp/cleft plasma, irregularly spaced ion injections interspersed with intervals of nearly constant cusp/cleft ion fluxes were observed. The data are consistent with temporal variations in the reconnection rate. At the time of the near conjugate observations, the data suggest that solar wind plasma entered the magnetosphere over an extended region of the magnetopause, i.e., not in small discontinuous patches.

Geophys. Res. Lett., 25, 2081-2084, 1998