Forecasting Tropical Cyclone Motion near Vietnam using a Nested Barotropic Model

On average about six tropical cyclones each year make landfall in Vietnam, claiming many human lives and causing extensive damage to property. It is therefore of great importance to accurately predict tropical cyclone motion and landfall when storms are approaching Vietnam. In this study, a nested barotropic model, developed originally at the University of Munich, is used to predict tropical cyclone motion in the region near Vietnam. Model forecasts at different initial times for tropical cyclones Niki (9613) and Ted (9516) are used to assess the potential of the model. The initial fields are obtained from the Australian Bureau of Meteorology's global spectral model. Synthetic data are generated to define the tropical cyclone circulation, consistent with the observed location, intensity, size and past motion. On average the position errors in these experiments are about 128 km after 24 h and 237 km after 48 h. Numerical experiments are conducted to investigate the sensitivity of cyclone motion over the South China Sea to the assumed vortex structure. It is found that the predicted cyclone track can be sensitive to the initial vortex structure.