Monday, 15 January 2007: 4:00 PM
The interannual and interdecadal variability in hurricane acticity over the Atlantic and Eastern Pacific Ocean
214C (Henry B. Gonzalez Convention Center)
The investigation of the interannual and interdecadal variations in hurricane activity have been an important topic lately, especially with regard to their implications for climate change issues. On the interannual time-scale, El Niņo has a significant impact on hurricane activity in the Atlantic and Eastern Pacific Ocean Basins. Various atmospheric and oceanic parameters that influence hurricane development become significantly altered during an El Niņo event, leading to suppressed easterly wave development and growth in the Atlantic, but more activity in the Eastern Pacific Ocean basin. The effect of the El Niņo/La Niņa cycle on hurricane intensity, however, is not straightforward. This study examined the interannual variability of hurricane intensity (measured as wind speed and interpreted through the Saffir-Simpson Scale) from 1938 through 2005 in both basins. These data were then compared with the occurrence of El Niņo/La Niņa events as defined using the Japan Meteorological Association (JMA) index. El Nino/La Nina variability superimposed on variability associated with the Pacific Decadal Oscillation (PDO) was also examined here. Not surprisingly, during an El Niņo year the intensity of Atlantic hurricanes was found to be weaker than during a neutral year or a La Niņa year, but these conclusions were opposite in the Eastern Pacific Ocean basin. There were also significant differences found in hurricane intensity between El Nino and La Nina years when the PDO was in phase 1, rather than when the PDO was in phase 2. Finally, this study also examined the interannual variation in hurricane intensity by genesis region (i.e. Atlantic: the eastern and western Atlantic Ocean Basins, the Caribbean, and the Gulf of Mexico; Eastern Pacific: divided into quadrants using 20o N and 125o W ).