Thursday, 26 January 2012: 11:45 AM
Impacts of Climate Variability on North Atlantic Tropical Cyclones Tracks
Room 355 (New Orleans Convention Center )
We examine the relationship between North Atlantic tropical cyclone (TC) tracks and the large-scale steering flow using best-track data for the 1950 to 2010 hurricane seasons. We categorize each cyclone into one of three groups according to their track type. When examining the influence of climatological events, a weakening in the subtropical high during El Niņo, when compared to La Niņa, results in more recurving ocean TCs than recurving landfall TCs. Positive phases of the Atlantic Meridional Mode are associated with an increase in the percentage of recurving ocean TCs and a decrease in the percentage of straight moving TCs. Furthermore, using the Beta and Advection Model a difference in tracks for El Niņo versus La Niņa was found, regardless of genesis location, suggesting an alteration in the large-scale circulation, whereas the track changes associated with variations in the Atlantic Meridional Mode are due to a systematic shift in genesis location.
To help understand the potential impacts of rising CO2 on TCs, climate model simulations are examined for changes in track density associated with variations in the large-scale steering flow and genesis location. For the 17 model ensemble mean, changes in the winds fields and Genesis Potential Index (GPI) result in minimal changes in track density whether examined individually or as a combined effect. Both impacts agree on a slight decrease in the projected track density for the Southern Gulf of Mexico and very Western Caribbean; however, this change is not statistically significant.