An analytical framework for rapid estimate of rain rate during tropical cyclones

Abstract

An analytical framework for rapid estimate of rain rate during a translating tropical cyclone was proposed in this study. The efficient analysis framework for rain field is based on the observation that rain-induced momentum flux at Earth's surface cannot be ignored. The total surface stress results mainly from momentum flux contributions of wind and rain. A height-resolving wind field was utilized during the model construction leading to a linear, analytical solution of the surface rain rate. The obtained rain rate model explicitly depends on parameters for a typical tropical cyclone wind field simulation, namely storm location, approach angle, translation speed, radius of maximum wind, pressure profile, surface drag coefficient, and turbulent diffusivity. Hence, it could be readily implemented into state-of-the-art tropical cyclone risk assessment using the Monte Carlo technique. The rainbands in the proposed methodology were simulated using a local perturbation scheme. Sensitivity analysis of the rainfall field to the abovementioned parameters was comprehensively conducted. The results generated by the present analytical framework for rapid estimate of rain rate during tropical cyclones are consistent with field measurements.