Ionospheric Polar Cap Growth During Superstorms

It is well established that the size of the ionospheric polar cap grows larger during times of substorms or other geomagnetically active periods. Previous work indicates that the radius of the polar cap is a weak function of the cross polar cap potential in the ionosphere. Observations from the DMSP spacecraft show that the size of the polar cap is significantly larger during storms and superstorms than during nominal quiet conditions. We will show the temporal change in size the polar cap observed by DMSP during the November 2003 superstorm and compare it to other parameters (potential, DST, IMF, etc.) during the storm. We will also compare these results with a similar analysis done during a relatively quiet period. We are attempting to see if an empirical model of the polar cap size during superstorms can be established. If workable, such a model would be useful in current magnetospheric and ionospheric modeling efforts.