Daily and weekly sea surface temperature data of Tropical Rainfall Measuring Mission (TRMM) Microwave Imager and Advanced Microwave Scanning Radiometer-Earth Observing System sensors are used as forcing of the underlying sea surface in the mesoscale numerical model to simulate Typhoon Dujuan that moved across the South China Sea in 2003. The numerical results show that different SSTs near the typhoon center result in differences in the atmospheric wind field, indicating that the model has a fast and obvious response to SSTs. Different SST influences the intensity and track of Dujuan to some degree and has significant impacts on its precipitation and latent heat flux near the eye. The SST influence on Dujuan is mainly fulfilled by changing the latent heat flux between the ocean surface and the atmosphere above.
Tropical cyclone （TC） Nargis （2008） made landfall in Myanmar on 02 May 2008, bringing a storm surge, major flooding, and resulting in a significant death toll. TC Nargis （2008） displayed abnormal features, including rare eastward motion in its late stage, rapid intensification before landing. Using reanalysis data and a numerical model, we investigated how a low-latitude westerly wind modulated TC Nargis’ （2008） track and provided favorable atmospheric conditions for its rapid intensification. More importantly, we found a possible counterbalance effect of flows from the two hemispheres on the TC track in the Bay of Bengal. Our analysis indicates that a strong westerly wind burst across the Bay of Bengal, resulting in TC Nargis’ （2008） eastward movement after its recurvature. This sudden enhancement of westerly wind was mainly due to the rapidly intensified mid-level cross-equatorial flow. Our results show that a high-pressure system in the Southern Hemisphere induced this strong, mid-level, cross-equatorial flow. During the rapid intensification period of TC Nargis （2008）, this strong and broad westerly wind also transported a large amount of water vapor to TC Nargis （2008）. Sufficient water vapor gave rise to continuously high and increased mid-level relative humidity, which was favorable to TC Nargis’ （2008） intensification. Condensation of water vapor increased the energy supply, which eventuated the intensification of TC Nargis （2008） to a category 4 on the Saffir-Simpson scale.
LI Wei-WeiWANG ChunzaiWANG DongxiaoYANG LeiDENG Yi
