Spatio-temporal Patterns of Tropical Cyclone Potential Intensity from Reanalyses and Global Climate Models

Numerous recent studies have reported increasing tropical cyclone (TC) potential intensity over the North Atlantic main development region (MDR) during the past 30 years. Such trends in potential intensity are generally attributed to warmer sea surface temperatures and cooler tropopause temperatures during the recent period. Although trends in MDR potential intensity have been examined, there has been less focus on a) whether these trends vary spatially across the North Atlantic basin, and b) the relationship between spatio-temporal patterns in potential intensity and spatio-temporal patterns in TC frequency and intensity. Therefore, this study examines the spatial and temporal variability of potential intensity over the North Atlantic for the period 1979-2014. Monthly and seasonal potential intensity is calculated from the NASA Modern Era Reanalysis fields and then averaged over equal-area subregions covering the North Atlantic basin. Potential intensity trends are determined for each subregion, as is the ratio of per region average TC intensity to potential intensity for each season during the 36-year period of study. Additionally, the relationships between per region potential intensity, tropopause temperature, and sea surface temperature are quantified.

For comparison, potential intensity also is calculated from four different climate models with horizontal grid spacing ranging from 20 to >100 km. Although all of the climate models fail to reproduce the spatial and intensity distributions of observed North Atlantic TCs, the models yield similar spatial and temporal patterns of potential intensity when compared to the results obtained from reanalysis data. These results suggest that if we can generate probabilistic statistical models for seasonal or monthly per region TC intensity using potential intensity as a predictor, then we may be able to utilize potential intensity estimates from climate model simulations to explore future changes to TC intensity.