Numerical Simulation of the Influence of Sea Surface Temperature on Translating Tropical Cyclones

A three-dimensional numerical model with a domain of 3000 km×3000 km and horizontal resolution of 60 km is used to study the influence of sea surface temperature (SST) on the behavior of tropical cyclones translating with mean flows in the Northern Hemisphere. We find that tropical cyclones tend to move into regions of warmer SST when a gradient of SST is perpendicular to the mean ambient flow vector (MAFV). The model results also indicated that a region of warmer SST situated to the right side of the MAFV is more favorable for storm intensification than to the left side due to the asymmetries in air-sea energy exchanges associated with translating tropical cyclones. The model tropical cyclone intensifies and has greater rightward deflection in its path relative to the MAFV when translating into the region of warmer SST. The model tropical cyclone intensifies when its center travels along a warm strip, while it weakens along, but does not move away from, a cool strip. The results suggest that the SST distribution not only affects the intensity and path of tropical cyclones frictionally, but also affects them thermally. The enhanced evaporation and convergence over the warm SST provide a favorable condition for the growth of the tropical cyclone, and lead to a gradual shift of the storm center toward the warm ocean.