A possible mechanism responsible for exceptional rainfall over Taiwan from Typhoon Morakot

During 6-9 August 2009, Typhoon Morakot hit Taiwan with exceptional rainfall and caused severe flooding and landslides, which resulted in a large number of human loss of life and significant property damage. The rainfall intensity broke the 50-year record and was largely under-forecasted. In this study, we have identified a possible mechanism responsible for this unusually heavy rainfall. It is found that the presence of the tropical storm Goni upstream of Morakot may be an important factor for the maintenance and intensification of Morakot. Goni transported a large amount of moisture and energy to Morakot. Numerical simulations indicate that the interaction of Goni and Morakot accounts for about 30% more rainfall than if Goni was not presented. This study may explain the unusual amount of rainfall for Morakot and thus provide additional considerations for future forecasts of similar situations. Copyright (C) 2011 Royal Meteorological Society