An Ocean-Based Potential Intensity Index for Tropical Cyclones

Improvement in tropical cyclones' intensity prediction is an important ongoing effort. Cooling of the ocean by storm mixing reduces storm intensity by reducing the air-sea enthalpy flux. Here, we modify the widely used Sea Surface Temperature Potential Intensity (SST_PI) index by including information from the upper subsurface ocean to form a new Ocean Cooling Potential Intensity index, OC_PI. Applied to a 14-year (1998-2011) Western Pacific typhoon archive, the correlation coefficient between the predicted maximum intensity and the observed peak intensity increased from 0.08 to 0.31. For the sub group of slow-moving TCs that has the strongest interaction with subsurface ocean, r2 increases to 0.56. OC_PI thus contributes to the improvement on the existing PI through incorporation of ocean's subsurface information.