What causes the extremely heavy rainfall in Taiwan during Typhoon Morakot (2009)?

Despite its category-2 intensity only, Typhoon (tropical cyclone in the Western Pacific) Morakot produced a record-breaking rainfall in Taiwan. A cloud-resolving model is used to simulate this extreme rainfall event and understand the dynamic aspect under this event. Due to the interaction between Morakot and a monsoon system, a peripheral gale force monsoon surge appears to the south of Taiwan. The monsoon surge remains even in a sensitivity experiment in which Taiwan terrain is reduced. However, the rainfall amount in Taiwan is greatly reduced without high topography over Taiwan, suggesting the important role the local topography plays in producing heavy rainfall. The overall numerical results indicate that it is the interaction among the typhoon, monsoon system, and local terrain that led to this extreme event. Copyright (C) 2010 Royal Meteorological Society