SENSITIVITY ANALYSIS OF EXTREME PRECIPITATION EVENTS

A sensitivity analysis of the frequency of extreme precipitation event s is performed. Extreme events in the form of total precipitation (e.g . over a month or season) exceeding a relatively large threshold (i.e. extremely wet conditions) or falling below a relatively small thresho ld (i.e. extremely dry conditions) are treated. To allow for the posit ive skewness of the distribution of total precipitation, a power trans formation to normality is used. The relative sensitivities of extreme precipitation events to the median and to the scale parameter of this distribution are examined. It is shown that these relative sensitiviti es are both generally greater the more extreme the event. Moreover, th e relative sensitivity to the scale is greater than that corresponding to the median for extreme wet events, whereas the opposite is true fo r extreme dry events. These theoretical results are illustrated throug h use of a network of precipitation observations in Spain.