HR: 12:05h
AN: A42B-07    [Abstracts]
TI: Statistical Analysis of Environmental Factors Affecting the Genesis of Tropical Atlantic Cyclones in Climate Model Simulations
AU: * Saravanan, R
EM: sarava@tamu.edu
AF: Dept. of Atmospheric Sciences, 3150 Texas A&M University, College Station, TX 77843, United States
AU: Mahajan, S
EM: salilmahajan@neo.tamu.edu
AF: Dept. of Atmospheric Sciences, 3150 Texas A&M University, College Station, TX 77843, United States
AB: Tropical cyclogenesis is affected by several large-scale environmental factors, such as the vertical wind shear, relative humidity, etc. It is therefore very important to understand how these factors are affected by climate variations, both natural and anthropogenic. Although coarse-resolution climate models cannot be used to study the actual genesis of tropical cyclones, they can be used to investigate the trends in the environmental factors that affect them. In this study, we perform a statistical analysis of the ensemble of climate model simulations carried out for the Intergovernmental Panel on Climate Change (IPCC) 4th Assessment. We consider both model simulations of the 20th century and model projections for the 21st century. Multivariate analysis is used to identify statistically robust indicators of tropical cyclone genesis for the 20th century simulations, by comparing the simulated large-scale environmental factors to observed cyclone frequencies. The focus is on the Main Development Region (MDR) for tropical cyclones in the Atlantic, but the remote influence of phenomena such as the El Nino-Southern Oscillation (ENSO) and West African rainfall is also considered. Our results show that climate model integrations for the 20th century have considerable difficulty in simulating the environmental factors that affect tropical cyclogenesis, such as the climatological vertical shear in the MDR region and correlations with the El Nino-Southern Oscillation. Model simulations for the 21st century reveal trends in the environmental vertical shear that can have a dynamical effect on tropical cyclogenesis, which may partially offset the thermodynamic effect of increased sea surface temperatures.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3374 Tropical meteorology
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly