Structural Changes of a Tropical Cyclone during Landfall: β-plane Simulations

This study investigated the effects of landfall on the structure of atropical cyclone (TC). Numerical simulations were performed using theWeather Research and Forecasting Model on a β-plane. Two landfallexperiments, one with an east--west and another with a north--south orientedcoastline, were performed.Similar to previous studies on an f-plane, large-scale flows in thelow-to-middle troposphere were modified due to friction. A pair of counterrotating gyres was found, which was shown to be consistent with the slightdeflection of the TC relative to the control experiment without land.Compared to previous f-plane simulations, because of the inherent asymmetriesdue to the β-gyres, the large-scale pattern of flows andconvergences/divergences related to friction were found to depend oncoastline orientations. On the other hand, regardless of the coastlineorientation, convergences were found to be stronger to the left for bothcases near landfall, as in previous f-plane simulations. Such a convergencepattern subsequently induced a change in convection and rainfall at theeyewall.