Intensity of Recurved Typhoons

Abstract

The maximum wind speed obtained by reconnaissance aircraft in recurved typhoons is examined for 66 cases from 1957 to 1968 for 2-3 days after recurvature from a westward to an eastward component of motion. The maximum wind decreases at a variable rate as the storms move out of the tropics, but a fairly uniform behavior is found if the maximum speed at any given time after recurvature is normalized to a percentage of the highest speed attained during the life of a typhoon. For latitude increments in position of up to about 8 deg in 48?72 hr a linear relation gives results within fairly narrow limits. For longer displacements a logarithmic relation is indicated. The latter is compared with the variation of maximum wind speed in steady-state storms with latitude. It appears that a large fraction of the decrease in intensity after recurvature can be ascribed to the latitude effect itself but that an additional smaller term possibly related to decreasing ocean and air temperatures is present.