A TECHNIQUE TO MEASURE TRENDS IN THE FREQUENCY OF DISCRETE RANDOM EVENTS

Time series of extreme meteorological and hydrological events frequent ly present problems with the use of traditional parametric statistical techniques. These difficulties arise from the frequent use of count d ata, the presence of zero values, data with nonnormal distributions, a nd/or truncated data. This paper presents a parametric method to evalu ate temporal trends in extreme events that overcomes these problems. T he technique includes the testing of the arrival structure of extreme event data for the Poisson distribution, then prepares and tests time series of interarrival times for trend analysis through linear regress ion. Nor'easters along the east coast of the United States and heavy r ainfall events at Covington, Louisiana, are examined.