Alternative expressions for the maximum potential intensity of tropical cyclones.

This article critically examines Emanuel’s formulation of maximum potential intensity (E-PI) for tropical cyclones, which predicts an upper limit on maximum wind speeds based on atmospheric and oceanic parameters. The authors propose an alternative formulation that accounts for the horizontal temperature gradient at the radius of maximum wind, showing it depends on boundary layer dynamics and can differ significantly from E-PI assumptions, thereby explaining observed cases of superintensity where storms exceed E-PI limits, as illustrated by Hurricane Isabel 2003. They demonstrate that supergradient winds alone cannot fully explain superintensity and highlight that both E-PI and the alternative formulation link maximum kinetic energy density to the partial pressure of water vapor at the surface, reflecting a balance between kinetic energy generation and potential energy release from condensation. The study also discusses limitations of E-PI related to assumptions about outflow temperature and thermodynamic disequilibrium, suggesting that condensation-induced atmospheric dynamics offer a more general framework for understanding maximum storm intensity.