Relationship between Vertical Wind Shear and Typhoon Intensity Change, and Development of Three-Predictor Intensity Prediction Model

Abstract

The relationship between vertical wind shear and tropical cyclone intensity change at each time interval of 12, 24, 36, 48, 60, and 72 h in the western North Pacific is investigated using the NCEP/NCAR reanalysis data from 1983 to 1996. As expected, regression coefficients at all time intervals are positive (storm intensity is represented by the minimum surface pressure), indicating that the vertical shear weakens storm intensity. When the total sample is stratified by latitude band, it is found that the intensity of low-latitude storms is more sensitive to vertical shear than that of high-latitude storms. This is consistent with theoretical results and observations for Atlantic storms. A minimal predictor model of predicting tropical cyclone intensity change in the western North Pacific up to 72 h is presented. The model has only three predictors (potential intensification, intensity change during previous 12 hours, and vertical shear), but the explained total variance is shown to be reasonably good in comparison to other statistical models with larger numbers of predictors. The average intensity prediction errors from the three-predictor model are reduced when the multiple linear regression method is replaced by the back-propagation neural network.