Climatic Characteristics of Tropical Cyclones Landfalling in China—— Three sorts of landfalling tropical cyclones and their interrelations

In consideration of the fact that the position data of landfalling tropical cyclone (TC) in China includes only place names, using the Northwest Pacific TC dataset and landfalling TC dataset during 1951-2004 from Shanghai Typhoon Institute of CMA, a computerization scheme for landfalling TC information is developed. The scheme consists of four aspects: approximation of coastal line, calculation of landfalling position, calculation of other parameters, and error correction. The assessment of the computerized data shows that the result of landfalling information computerization is satisfactory. Based on the above computerized data, climatic characteristics of landfalling TCs in China are investigated with a focus on three sorts of TCs landfalling in the mainland, Hainan and Taiwan and their interrelations. The results include the following six aspects. Firstly, regions most frequently affected by landfalling TCs were the east coast of Taiwan, the coastal region from Fujian Province to Leizhou Peninsula and the east coast of Hainan. Secondly, the east coast of Taiwan and parts of the coastal Zhejiang Province saw the strong landfalling TCs and their average intensity reached the typhoon level, with the strongest landfalling TCs up to the strong typhoon level in the southernmost of Taiwan. Thirdly, the TC landfalling season for China was from May to November, especially between July and September, with the highest frequency in August. Frequent intensity levels of landfalling TCs were mainly between tropical depression and typhoon, with the most frequent ones being strong tropical storm and typhoon. Fourthly, although frequencies of landfall TCs for the mainland, Hainan, Taiwan and the whole China all showed to different extents decreasing trends during the past 54 years, only the decreasing trend of landfalling TCs for Hainan is significant, while no obvious increasing or decreasing trend is found in frequencies of landfalling TCs with an intensity level of tropical storm or above. Fifthly, by and large, the mainland had the highest frequency of landfalling TCs, the earliest date of the first-landfall, the latest date of the last-landfall , and thus the longest landfalling season, while Taiwan had the lowest frequency of landfalling TCs, the lastest date of the first-landfall, the earliest date of the last-landfall, and thus the shortest landfalling season. Finally, viewing from an angle of the way of landfall, TCs landfalling in one region were the most frequent (79.2%), those in two regions the next (20.6%), and only one TC made landfall in three regions. Among the TCs landfalling in two regions, those with a track from Taiwan to the mainland had the highest frequency and weakened quickest in intensity, those with a track from Hainan to the mainland had the secondary highest frequency and weakened slowly, and those with a track from the mainland to Hainan had the third largest frequency and weakened quicker.