Estimation of cold ion outflow rates throughout a geomagnetic storm.

Abstract:

Low energy ions of ionospheric origin are believed to be a significant
contributor to the magnetospheric plasma population. Measuring these low
energy ions is challenging, though. Spacecraft charging effects usually
prevent direct detection using particle detectors.

In this paper we suggest a new approach, based on a combination of modelling,
synoptic observations and a novel technique to address these issues. We
thereafter use this approach to estimate outflow rates and transport of low
energy ions during the October 2002 geomagnetic storm selected by the GEM
community to benchmark models.

Our results indicate large variations in both outflow rates and transport
throughout the various phases of the storm. Prior to the storm main phase,
outflow rates are moderate, and the cold ions are mainly emanating from moderately
sized polar cap regions. Throughout the main phase of the storm, outflow
rates increase and the polar cap source regions expand. Furthermore, faster
transport, resulting from enhanced convection, leads to a much larger supply
of cold ions to the near Earth region.