In situ measurement of a newly created polar cap patch



[1] The Investigation of Cusp Irregularities 2 sounding rocket was launched 5 December 2008 at 1035 UT. We present an overview of the associated solar wind and auroral conditions, and we look in detail at the relationship between poleward moving auroral forms (PMAFs) and the creation of polar cap patches using ground-based optical and radar data as well as in situ data from the rocket payload. The solar wind was found to be dominated by a stable interplanetary magnetic field (IMF) Bz < 0 and by an IMF By > 0 situation. The aurora was characterized by a series of PMAFs throughout the period of interest. Associated with each PMAF were polar cap patches seen to emerge from the most poleward location of the PMAFs. On the basis of the available data, we present a conceptual model explaining the creation of the polar cap patches under the given solar wind and ionospheric conditions.