Statistics of Extreme Space Weather Events

Abstract Extreme events, while rare, can have a disproportionately large effect on our technologically dependent society. In this chapter, we review statistical approaches for estimating how likely such events are. In particular, we focus on the disturbance storm time ( Dst ) index, finding that the likelihood of an extreme geomagnetic storm ( Dst AE index, and extend our previous Dst work to also include the Dst proxy parameters Dxt and Dcx , which extend significantly further back in time. Additionally, we extend our previous analysis of solar proton events using a more rigorous approach. Our results suggest that these events are on the scale of 100-year solar storms; however, the extent to which they will occur in the future depends on a basic assumption in the methodology: time stationarity. We conclude by discussing the implications of this work, and suggest how future studies may improve our understanding.