Potential Intensity of Tropical Cyclones: Comparison of Results from Radiosonde and Reanalysis Data

Abstract

Long-term changes in the intensity of tropical cyclones are of considerable interest because of concern that greenhouse warming may increase storm damage. The potential intensity (PI) of tropical cyclones can be calculated from thermodynamic principles, given the state of the sea surface and atmosphere, and has been shown in earlier studies to give a reasonable estimate of maximum intensity for observed storms. The PI calculated using radiosonde data at 14 tropical island locations shows only small, statistically insignificant trends from 1980 to 1995 and from 1975 to 1995. In the mid-1990s PI at most of these stations does not show the strong increase that appears in global and regional PI calculated from reanalysis data. Comparison with results derived from reanalysis data suggests that previous adjustments to the reanalysis-derived PI may overstate PI after 1980 in some regions in comparison with that before 1980. Both reanalysis and radiosonde PI show similar interannual variability in most regions, much of which appears to be related to ENSO and other changes in SST. Between 1975 and 1980, however, while SSTs rose, PI decreased, illustrating the hazards of predicting changes in hurricane intensity from projected SST changes alone.