Locating the open-closed boundary during the passage of a corotating interaction region

Abstract:

During the 2007-2009 solar quiet period there existed a unique opportunity to study the synoptic variability of the open-closed boundary (OCB) using data provided by fluxgate magnetometers located at South Pole, McMurdo, and from a network of Automatic Geophysical Observatories distributed across the Antarctic continent. In Urban et al [2011], this synoptic variability was analyzed during a geomagnetic quiet period of early August 2008 and excellent (>83%) agreement was found between the experimental observations and the BATSRUS space weather model. In this paper we discuss the OCB's synoptic behavior under the forcing of a geomagnetic storm driven by a corotating interaction region and again compare these results to predictions made with different versions of BATSRUS model runs. Strictly adhering to the method developed in Urban et al [2011], we show only weak agreement between the experimental data and model during this geomagnetically-active time, independent of the model resolution and the incorporation of the Rice Convection Model. Given that a potential source of disagreement could be from the rigidity of the original open/closed field line determination technique itself (developed for geomagnetic quiescence), we adapt the technique to variations in local time and geomagnetic activity; any remaining discrepancies between the data and the model are investigated with DMSP spacecraft-determined boundary data.