V. K. Jordanova, C. J. Farrugia, J. M. Quinn
University of New Hampshire, Durham, New Hampshire

L. F. Burlaga, K. O. Ogilvie and R. P. Lepping
NASA Goddard Space Flight Center, Greenbelt, Maryland

Gang Lu
High Altitude Observatory, NCAR, Boulder, Colorado

A. J. Lazarus
Center for Space Research, Massachusetts Institute of Technology, Cambridge

R. D. Belian and M. Thomsen
Los Alamos National Laboratory, New Mexico

The passage at Earth of the January 1997 magnetic cloud and the following fast stream caused substantial storm activity. Particularly noteworthy is the enhancement of magnetopause currents, equivalent to a ~100 nT disturbance of the horizontal component of the Earth's magnetic field on the ground, when a ~3-hour-long burst of high density plasma impinged on the magnetosphere [see also Burlaga et al., 1997]. We study the ring current evolution during this storm period, employing our kinetic model of ring current-atmosphere interactions [Jordanova et al., 1996]. The H+ and O+ distribution functions thus obtained are compared with measurements made by the HYDRA instrument on the GGS spacecraft POLAR. The role of the time-varying magnetospheric electric field in the ring current formation, including a possible offset from the dawn-dusk direction, is investigated. The energy losses due to the three mechanisms considered, i.e., charge exchange, Coulomb collisions, and ion precipitation, are calculated as a function of time and inter-compared.

Jordanova et al. , JGR, 1996
Burlaga et al., These Proceedings