J. Adv. Model. Earth Sys., submited 9/14.

Tropical cyclones in the GISS ModelE2


Suzana J. Camargo
Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY

Adam H. Sobel
Department of Applied Physics and Applied Mathematics and Department of Earth and Environmental Sciences, Columbia University, New York, NY.

Anthony D. Del Genio, Jeffrey A. Jonas, Maxwell Kelley
NASA Goddard Institute for Space Studies, New York, NY.

Yun Lu
Ningbo Meteorological Office, Ningbo City, Zhejiang, China.

Daniel A. Shaevitz
Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY.

Naomi Henderson
Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY




Abstract

The authors describe the characteristics of tropical cyclone (TC) activity in the GISS general circulation ModelE2 with horizontal resolution 1◦ deg x 1◦ deg. Four model simulations are analyzed. In the first, the model is forced with sea surface temperature (SST) from the recent historical climatology. The other three are different idealized climate change simulations, namely (i) a uniform increase of SST by 2 degrees, (ii) doubling of the CO2 concentration, (iii) a combination of the two. These simulations were performed as part of the U.S. CLIVAR Hurricane Working Group. Diagnostics of standard measures of TC activity are computed from the recent historical climatological SST simulation and compared with the same measures computed from observations. The changes in TC activity in the three idealized climate change simulations, by comparison to that in the historical climatological SST simulation, are also described. Similarly to previous results in the literature, the changes in TC frequency in the simulation with a doubling CO2 and an increase in SST is approximately the linear sum of the TC frequency in the other 2 simulations. However, in contrast with previous results, in these simulations the effects of CO2 and SST on TC frequency oppose each other. Large-scale environmental variables associated with TC activity are then analyzed for the present and future simulations. Model biases in the large-scale fields are identified through a comparison with ERA-Interim Reanalysis. Changes in the environmental fields in the future climate simulations are shown and their association with changes in TC activity discussed.