The Dynamic and Thermodynamic Effects of Relative and Absolute Sea Surface Temperature on Tropical Cyclone Intensity

Several numerical experiments were performed to investigate the dynamic and thermodynamic effects of sea surface temperature （SST） on tropical cyclone （TC） intensity. The results reveal that the relative SST within a radius of 2-3 times the radius of maximum wind contributes positively and greatly to TC intensity, while the remote SST far away from the TC center could reduce storm intensity. The change of air sea temperature and moisture differences may be the reason why TC intensity is more sensitive to the relative rather than the absolute SST. As the inflow air moves toward the eyewall, warmer （colder） remote SST can gradually increase （decrease） the underlying surface air temperature and moisture, and thus decrease （increase） the air sea temperature and moisture differences, which lead to less （more） energy fluxes entering the eyewall and then decrease （increase） the TC intensity and make it less sensitive to the absolute SST change. Finally, with all the related dynamic and thermodynamic processes being taken into account, a schematic diagram for the effects of relative SST and absolute SST on TC intensity is proposed.