Abstract:Only 23 tropical storms occurred over the western North Pacific and the South China Sea during the tropical cyclone (TC) season 2009. Although the frequency of TCs is less than normal years, there are more TCs, ten out of twenty three, making landfall in China, typhoons are also more active than normal. The region of TC formation seems to be further west to the normal and shifts eastward from the beginning to the end of season. More TCs, about 26.1%, were formed in the South China Sea. Most of these TCs moved westward or northwestward, and the primary area attached by the landfall TCs is the South China. Landfall TCs bring extreme heavy rains. Further analysis shows that the TC genesis area and its migration are closely related to the evolution of the coupled air sea system of the tropics, that is, the updraft leg of Walker circulation shifts eastward together with the area of enhanced turbulent kinetic energy in both lower and upper troposphere and southerly surge. The primary tendency of TC tracks, as well as the high frequency of TCs’ making landfall on South China, is dominated by the local pattern of general circulation, especially the dominant belt like subtropical high. Meanwhile, the intense activity of individual storm is closely related to the enhanced regional turbulent kinetic energy in low levels and divergence in 200 hPa.