我国沿海主要省份热带气旋风雨因子危险性分析Ⅱ:年代际变化特征

利用热带气旋最佳路径资料和气象台站观测资料，以及风雨因子危险性模型，分别计算我国沿海主要省份热带气旋风因子危险性、雨因子危险性及总危险性，并对其年代际变化特征进行分析。结果表明:沿海主要省份热带气旋致灾因子危险性随着年代逐渐增大，风因子危险性呈逐年代减弱，而降水因子危险性则逐年代增加；与1970年代相比，热带气旋在2000年代更易带来强降水，但极端风速出现的概率减小，热带气旋活动频数偏少，热带气旋的平均强度略偏强且持续时间偏长；与1970年代相比，2000年代的热带气旋气旋性环流更强烈，其附近低层西南风异常伴随有异常的来自西南向的水汽输送，并产生西南-东北走向的异常水汽辐合带，在异常强烈的垂直运动作用下，更多的水汽将带入高层，有利于降水产生。 

ANALYSIS ON HAZARDS OF THE WIND AND RAIN FACTORS ASSOCIATEDWITH TROPICAL CYCLONES IN CHINA′S MAJOR COASTAL PROVINCES Ⅱ: INTERDECADAL CHANGES

Based on the best track dataset of tropical cyclones (TCs) and the wind and rain data observed at the relevant meteorological stations, and by adopting the hazard model, the hazards of wind factor, rain factor and their synthesis for the TCs affecting China's major coastal provinces were calculated in this study, respectively. The interdecadal change of these hazards was analyzed, and the results are as follows: The synthesized hazards increased decade by decade, while the hazards of the wind factor weakened and those of the rain factor enhanced. When comparing the conditions in the 2000s to those in the 1970s, the TCs resulted in heavier precipitation, the probability of extreme wind speed decreased, and the frequency of TC activities was fewer, with slightly stronger intensity and longer duration. In the 2000s, when compared to the 1970s, the TCs had stronger cyclonic circulation, and there was abnormal southwest wind at the lower troposphere with abnormal water vapor transmission, and generated an abnormal water-vapor convergence zone with a southwest-northeast trend. Under the effect of remarkable vertical movement, more vapor would be brought to the upper level, which helped generate rainfall in the 2000s.