The effects of climatological and persistence variables on the intensities of tropical cyclones over the eastern North Pacific Ocean

The effects of 10 climatological and persistence variables (latitude, maximum wind speed, 12-h change of maximum wind speed, longitude, distance to land, Julian date, sea surface temperature, speed of movement, zonal component of motion, and meridional component of motion) on changes of intensities of tropical cyclones over the eastern North Pacific Ocean were examined for the periods 1982-87 and 1988-93. Backward multiple regressions were performed to relate these 10 variables to changes in maximum intensity (as determined by wind speed) over periods ranging from 12 to 72 h. Latitude, maximum wind speed, and the 12-h change of maximum wind speed were the most significant variables. Each of the 10 variables was statistically significant at the 95% level at one or more of the time periods. Speed of movement, the component of motion, and the meridional component of motion were the least significant factors. The statistical relationships were rested using independent data from 1994. The mean absolute forecast errors ranged from 3.0 m s(-1) at 12 h to 13.2 m s(-1) at 72 h using one of two sets of regression equations developed in this study.