Observations of dayside magnetopause oscillations and concurrent temporal variations in cusp precipitation
Dempsey, Donna Lynn
Young, David T.
Doctor of Philosophy
On April 13, 1996, while Russia's Interball Tail spacecraft was travelling through the dayside magnetosheath, NASA's Polar spacecraft traversed the northern cusp. Transients observed in the data from the Interball Tail/SCA-1 particle instrument are shown to be multiple crossings of the magnetopause. Analysis of data from the SCA-1 instrument and magnetic field data from the MIF instrument shows quasi-periodic motions of the magnetopause. Simultaneous observations of changes in cusp precipitation by the Polar/TIDE instrument and changes in the He2+/H+ density ratio in the cusp by the Polar/TIMAS instrument show variations on the same time scale. We show that the variations in the cusp data observed by Polar are the result of changes in the reconnection rate at the magnetopause and that these changes are associated with the magnetopause oscillations observed by Interball.