Relative Sea Surface Temperature Regulates Tropical Cyclone Size‐Intensity Evolution Through Convective Features

Abstract

Relative sea surface temperature (SST), defined as local SST minus the tropical mean, is linked to tropical cyclone (TC) size growth, but its role in coupled size‐intensity evolution remains unclear. Using 23 years of global observations, we show that relative SST regulates very deep convection (infrared brightness temperature <208K), thereby modulating both TC intensification and size expansion. Across all intensity categories, convective areal extent increases systematically with relative SST. Higher relative SST enhances inner core convective coverage and expands the radial extent of very deep convection. For storms with similar incipient sizes, higher relative SST accelerates size expansion at a given intensification rate. Relative SST affects the peak intensity a storm can achieve, while peak size depends on both relative SST and incipient size. These findings identify relative SST as an important control on TC size–intensity evolution and highlight the influence of remote SST on TC development.