The 23rd Conference on Hurricanes and Tropical Meteorology

4D.12
EL NINO IMPACT ON LANDFALLING INTENSE TROPICAL CYCLONES

Mark A. Saunders, University College of London, Dorking, Surrey, UK; and F. P. Roberts

Any link between El Nino and tropical cyclone activity is of both scientific and financial interest. The latter comes from the potential predictability such a link offers. Gray (1984) first noted that seasonal hurricane frequency in the Atlantic is inversely correlated with El Nino. Gray, Landsea and coworkers have subsequently examined the effect of moderate to strong El Nino events on tropical cyclone frequencies in other ocean basins. They find that the impact of El Nino is strongest in the Atlantic. Recent research by O’Brien et al. (1996) has considered the effect of El Nino on US landfalling hurricanes. Their study shows that between 1949 and 1992 landfalling hurricanes are twice as common in a neutral El Nino year compared to a strong El Nino year. We extend the O’Brien et al. work by (i) using a longer El Nino database extending back to 1900, (ii) computing changes in landfalling frequencies on a 140km grid scale, and (iii) examining the impact of El Nino on landfalling events in three ocean basins (Atlantic, northwest Pacific, and southwest Pacific). We find that (a) over much of the Caribbean and Gulf of Mexico hurricane landfalls are a factor of two more common during La Nina months than during El Nino months (1900-1996 data); (b) for Queensland, Australia, intense cyclone landfalls are a factor of two more common during La Nina months than during El Nino months (1970-1997 data); (c) for southern Japan and the northern Phillipines typhoon landfalls are 20% more common during La Nina months than El Nino months (1965-1997 data). These findings offer useful predictability to seasonal landfalling forecasts

The 23rd Conference on Hurricanes and Tropical Meteorology