Sensitivity of Limiting Hurricane Intensity to SST in the Atlantic from Observations and GCMs

A statistical model for the intensity of the strongest hurricanes has been developed and a new methodology introduced for estimating the sensitivity of the strongest hurricanes to changes in sea surface temperature. Here, the authors use this methodology on observed hurricanes and hurricanes generated from two global climate models (GCMs). Hurricanes over the North Atlantic Ocean during the period 1981-2010 show a sensitivity of 7.9 +/- 1.19 m s(-1) K-1 (standard error; SE) when over seas warmer than 25 degrees C. In contrast, hurricanes over the same region and period generated from the GFDL High Resolution Atmospheric Model (HiRAM) show a significantly lower sensitivity with the highest at 1.8 +/- 0.42 m s(-1) K-1 (SE). Similar weaker sensitivity is found using hurricanes generated from the Florida State University Center for Ocean-Atmospheric Prediction Studies (FSU-COAPS) model with the highest at 2.9 +/- 2.64 m s(-1) K-1 (SE). A statistical refinement of HiRAM-generated hurricane intensities heightens the sensitivity to a maximum of 6.9 +/- 3.33 m s(-1) K-1 (SE), but the increase is offset by additional uncertainty associated with the refinement. Results suggest that the caution that should be exercised when interpreting GCM scenarios of future hurricane intensity stems from the low sensitivity of limiting GCM-generated hurricane intensity to ocean temperature.