Actually the heat is pulled from surface water as evaporated water vapor that rises. This creates the updraft in the Hurricanes center. So after a Hurricane comes through the surface water is cooled. Winds also help evaporate and cool the water. When you are talking power, the volume of depth of heated water is important. Basically how much heated water can evaporate. So it is not just temperature, but total heat content. This is why hurricanes weaken over shallow water also.
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