Simulating tropical cyclone activities using regional climate model Tuan-Long TRINH, Hoang-Hai BUI, Van-Tan PHAN, Quang-Trung NGUYEN Department of Meteorology Hanoi University of Science, VNU ABSTRACT The Regional Climate Model (RegCM3) from ICTP (International Center for Theoretical Physics) with roughly 36-km horizontal grid spacing is used to simulate the inter-annual variability of tropical cyclones activities in the Northwest Pacific Ocean. The simulation domain is from 0N to 33N and from 100E to 160E. Numerical experiment was carried out in 1995-1997, remarkable years when the ENSO event shifted from cold phase to warm phase. Output fields of RegCM3 were interpolated to 4 levels (850hPa, 700hPa, 500hPa, 300hPa) and the criterion for a possible candidate of TC was selected with a standard of vortices (0.5x10 -5 ). If the center of vortex and sea level pressure (SLP) center are found with bi-rational interpolation, other criteria will be checked to confirm “TC is detected”, including the anomaly of temperature at each level, the outer core wind strength (>5m/s on 850 mb) and the decrement of pressure (> 1hPa). Results show that the number, position and motion of detected TCs agree well with the observation. The number of TCs is in general seasonally well represented with the highest one in August. However, “detected TCs” occur also in the end of winter, which is usually not the case of the observed TCs. -------------------------- Keywords : tropical cyclone, hurricane, regional climate model, Northwest Pacific Ocean, tropical cyclone detection scheme. 1. Introduction Today, there are many evidences showing that climate change is related to abnormal changes of weather and climate in many regions on the earth. The cause of large scale circulation changes is mainly from global warming and there is an increasing trend for extreme events, including tropical cyclones (TCs). The detection scheme which uses outputs of regional climate models has been tested in this study. Outputs of RegCM3 with the roughly 36-km horizontal grid spacing in North Western Pacific domain (0-33N, 100-160E) to simulation operation of TCs. Then the results of detection process are assessed detection ability to develop scenario of operation TCs in the future. The formation conditions of TCs have been concluded in details by previous studies, these conditions include: high enough surface temperature, weak enough vertical wind shear strong enough, large scale vortices in the troposphere… Usually, The resolution of regional climate models using lower than scale of tropical cyclone, if Its exist on climate model, Its express quite weak. For global climate models have low resolution very low, tropical cyclone area is just expressed as an