A Simulation Study of the Landfall of Tropical Cyclones

Abstract

By use of a triply nested, movable mesh model, several ideal simulations OF tropical Cyclone landfall were performed for a strong zonal flow of ?10 m s-1. The integration domain was a 37 ? 45° channel with the innermost mesh having a 22 ? 22 point resolution of 1/6°. General characteristics similar to observed landfalling tropical cyclones are obtained in the primary simulation experiment including an abrupt change in the low level (?68 m) winds at the coastline and a decay of the tropical cyclone at it moves inland. Additional interesting features subject to model and experimental limitations include: little noticeable track change of the model storm when compared to a control experiment with an ocean surface only; a possible temporary displacement or the center of the surface wind circulation from the surface pressure center at landfall; and a distinct decrease in kinetic energy generation and precipitation a few hours after landfall. The sensitivity to the specified land surface conditions was analyzed by performing additional experiments in which the land surface conditions including surface temperature, moisture, and distribution of surface roughness were changed. It was found that a reasonable change in some of these land conditions can make a considerable difference in behavior for a landfalling tropical cyclone. It was also shown that a small, less intense model storm fills less rapidly. This corresponds well with observations that many landfalling hurricanes decay to approximately the same asymptotic value one day after landfall.