Changes in North Atlantic Basin Hurricanes

• Activity Number: 550
• Type: Invited
• Date/Time: Wednesday, August 3, 2011 : 2:00 PM to 3:50 PM
• Sponsor: Section on Risk Analysis
• Author(s): Robert B. Lund*+
• Companies: Clemson University
• Keywords: CUSUM Statistic ; Poisson Processes ; Tropical Cyclones ; Wind Speeds ; Climate Change ; Brownian Bridge

Abstract

This talks overviews changes in the North Atlantic Basin tropical cyclone record since 1851. A changepoint test is first developed for categorical data via maximums of statistics that have marginal chi-squared distributions. Statistically, the asymptotic distribution of the test statistic is shown to involve the supremum of sums of squares of scaled Brownian bridge processes. The results are used to identify times of change (lack of homogeneity) in the North Atlantic Basin tropical cyclone record. We find an increase in storm counts in the 1930s that is generally attributed to the onset of aircraft surveillance. We also find a very significant increase in counts circa 1995 that does not seem to be linked to any changes in data collection techniques. The good news is that no recent changes in the individual storm strengths are found. The end conclusions are essentially the opposite of recent testimonial given in the United States Senate.