The vertical structure of tangential winds in simulated tropical cyclones

We examine the vertical structure of the tangential winds in tropical cyclones within a set of idealized tropical cyclone simulations, using WRF v3.1.1. By varying the size of the Radius of Maximum Winds (RMW) of an initially weak vortex, we are able to simulate quasi-steady state tropical cyclones of similar intensities, but with a broad range of sizes. Starting from an initially vertical RMW, all simulations develop an outward sloping RMW, with the magnitude of the slope proportional to the size of the RMW. This approximately linear relationship is broadly consistent with that found in observations and theory (Stern and Nolan, 2009). However, the slope of the RMW is systematically larger in the simulations. Reasons for this behavior will be explored.

Despite having different sizes and fluctuating intensities, all simulated storms share a similar vertical profile of maximum tangential winds. Time-variability of this profile is mostly due to variability in the distribution of supergradient winds. The normalized vertical decay of tangential winds within the idealized simulated storms is quite similar to that of both real storms and that predicted by theory. Sensitivity of the vertical structure to vertical resolution, microphysics parameterization, initial structure, and potential intensity will also be evaluated.