The effects of complex terrain on tropical cyclone track, intensity, and rainfall during TCS-08

During the Tropical Cyclone Structure-2008 (TCS-08) experiment, two typhoons made landfall on the island of Taiwan: Sinlaku and Jangmi. Both of these storms produced extremely high rainfall totals with maximum amounts of 1611 mm (63.43 in) and 1124.5 mm (44.27 in), respectively. Previous studies have shown that the orography of Taiwan can alter the track and structure of passing tropical cyclones, as well as increase the total rainfall due to upslope forcing. This study investigates the relative importance of these effects for Sinlaku using simulations with the tropical cyclone version of the Naval Research Laboratory's Coupled Ocean-Atmosphere Mesoscale Predictions System (COAMPS-TC©). A control simulation is compared with runs where the topography of Taiwan is replaced by flat land and by water. In the absence of topography, the rainfall amounts are dramatically reduced due to both the absence of upslope forcing and the early recurvature of the track before landfall is achieved. This results in the strongest convection remaining northeast of Taiwan and a shorter duration of rainfall. Preliminary results for Jangmi will also be presented.