Dependence of Tropical Cyclone Outer-Size Expansion Rate on Sea Surface Temperature: Observations, Reanalysis, and Idealized Simulations

Dependence of tropical cyclone outer-size expansion rate on sea surface temperature (SST) is examined in best-track data, reanalysis data, existing aquaplanet simulation dataset, and idealized f-plane simulations. Radius of 17 m/s wind (r₁₇) in best-track data and radius of 8 m/s wind (r₈) reanalysis data consistently show that 48-h and 24-h maximum expansion rate significantly increases with SST in Western North Pacific and Eastern North Pacific but not in North Atlantic. Existing aquaplanet simulation dataset shows expansion rate of r₈ increases with SST for large storms. Idealized f-plane simulations show expansion rate of r₈ increases with SST. In summary, evidence of higher SST supporting faster expansion rate of the TC is found in idealized simulations, and such relation is also found in Eastern and Western North Pacific on Earth.