LAUSR

Abstract The wind field model is one of the most important components for the tropical cyclone hazard assessment, thus the appropriate design of this element is extremely important. While solving the fully non-linear governing equations of the wind field was demonstrated to be quite challenging, the linear models showed great promise delivering a simple solution with good approximation to the wind field, and can be readily adopted for engineering applications. For instance it can be implemented in the Monte Carlo technique for rapid tropical-cyclone risk assessment. This study aims to develop a height-resolving, linear analytical model of the boundary layer winds in a moving tropical cyclone. The wind velocity is expressed as the summation of two components, namely gradient wind in the free atmosphere and frictional component near the ground surface. The gradient wind was derived straightforwardly, while the frictional component was obtained based on the scale analysis of the fully non-linear Navier-Stokes equations. The variation of wind field with respect to the angular coordinate was highlighted since its contribution to the surface wind speed and associated spatial distribution cannot be ignored in the first-order approximation. The results generated by the present model are consistent with tropical cyclone observations.