Tropical Cyclogenesis Index:

an application to climate change

Suzana J. Camargo1,  Michael K. Tippett2, Adam H. Sobel1,3,

Gabriel A. Vecchi4, and Ming Zhao4

(1) Lamont-Doherty  Earth Observatory, Columbia University, Palisades, NY

(2) International Research Institute for Climate and Society, Columbia University, Palisades, NY

(3) Department of Applied Physics and Applied Mathematics and

Department of Earth and Environmental Sciences, Columbia University, New York, NY

(4)  Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, NJ

In Tippett et al. (2011), a Poisson regression between observed tropical cyclogenesis climatology and observed (reanalysis) large-scale variables was used to construct a tropical cyclogenesis index. Here, we first apply this index directly to the environmental variables of the 50km HIRAM model forced by present and future SST scenarios and compare the index behavior with model cyclogenesis. Second, we use the regression methodology with model tropical cyclogenesis and model environmental variables, and compare the model-based index with observation based one. Various environmental variables are tested to determine the optimal combination for the model data. We identify the differences with the observed derived index and apply the model derived index to climate change model data and analyze its performance. Finally, we apply the regression methodology to the 4 future scenarios and determine the sensitivity of the index to the SST different forcing scenarios and different environmental variables, and compare with the model indices obtained for the present.

Reference:

Tippett, M.K., S.J. Camargo, and A.H. Sobel, 2011. A Poisson regression index for tropical cyclone genesis an the role of large-scale vorticity in genesis. J. Climate, early online, doi: 10.1175/2010JCLI3811.1.