The Effect of Large B$_{y}$ on Currents in the Polar Cap

In the polar cap, plasma flow is driven primarily by \textbf{E} x \textbf{B} drift. The two-cell convection pattern flows anti-sunward on the noon-midnight line and returns sunward on the equatorward edges of the polar cap. As the magnitude of the dawn-dusk interplanetary magnetic field (IMF B$_{y})$ grows, one of the cells enlarges as the other shrinks. During these times, we predict that a current will flow out of one pole, travel along the Earth's bow shock, and then into the other pole along open field lines. This current should create a small cell of convection entirely on open field lines. We have used the electron flux instruments and plasma drift meters on DMSP satellites to locate the open-closed field line boundaries and the convection reversal boundaries for comparison with each other. We will present statistics and cases showing how the polar current depends on IMF B$_{y}$.