“…This function assumes damage only occurs when the value of the given meteorological variable exceeds u X . For wind gust speeds the threshold u X = 20ms −1 is often used, however Klawa and Ulbrich (2003) note this threshold may be Box 1. Definition of Aggregate Severity Index (ASI) Suppose that N storms impact a given location over a specified time period, and let {X 1 , X 2 , …, X N } be the values of a meteorological hazard variable (e.g.…”