An Analytic Model for Tropical Cyclone Outer Winds.

The variation of Tropical cyclone azimuthal wind speed (V) with distance from storm center (r) is a fundamental aspect of storm structure with important implications for risk and damages. The theoretical model of Emanuel (2004, https://doi.org/10.1017/CBO9780511735035.010), which applies outside the rainy core of the storm, matches radiatively‐driven subsidence and Ekman suction rates just above the boundary layer to obtain a nonlinear differential equation for dV/dr. This model is appealing because of its strong physical foundation, but lacks a known analytic solution for V(r). In this paper, I obtain an analytic solution to V(r) for the Emanuel (2004, https://doi.org/10.1017/CBO9780511735035.010) outer wind model. Following previous work, I then use this solution to explore properties of merged wind models that combine the outer model with an inner model, which applies to the rainy core of a storm. Plain Language Summary: The swirling winds of hurricanes extend far away from their centers, fading away into background weather. Previous work proposed a theoretical model to explain how these swirling winds decrease with distance from the storm center for areas outside the rainy core of the storm. But this model has not previously been solved with pencil‐and‐paper methods. Here, I find a new mathematical formula that solves the model for how winds weaken away from the center of a hurricane. I then use the solutions to examine how hurricane winds near the center of a storm relate to the winds far from the center, and what this implies about how hurricanes behave. Key Points: Analytic solutions are derived for the previously unsolved outer wind model of Emanuel (2004, https://doi.org/10.1017/CBO9780511735035.010)Analytic wind profile calculations enable faster merged wind profile calculations, following Chavas et al. (2015, https://doi.org/10.1175/jas-d-15-0014.1)Scaling of merged wind profiles suggests decreases in the radius of maximum wind with warming, at constant outer size [ABSTRACT FROM AUTHOR]