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

This study investigated the effects of landfall on the structure of a tropical cyclone (TC). Numerical simulations were performed using the Weather Research and Forecasting Model on a β-plane. Two landfall experiments, one with an east--west and another with a north--south oriented coastline, were performed. Similar to previous studies on an f-plane, large-scale flows in the low-to-middle troposphere were modified due to friction. A pair of counter rotating gyres was found, which was shown to be consistent with the slight deflection of the TC relative to the control experiment without land. Compared to previous f-plane simulations, because of the inherent asymmetries due to the β-gyres, the large-scale pattern of flows and convergences/divergences related to friction were found to depend on coastline orientations. On the other hand, regardless of the coastline orientation, convergences were found to be stronger to the left for both cases near landfall, as in previous f-plane simulations. Such a convergence pattern subsequently induced a change in convection and rainfall at the eyewall.