全球变暖背景下西北太平洋热带气旋活动的气候特征

Climatic characteristics of tropical cyclone activities in the western North Pacific under the global warming

利用中尺度大气数值模式(MM5)研究了全球气候变暖的背景下西北太平洋热带气旋活动的气候特征.设计了两组模拟试验,每组实验模拟44个热带气旋共88个个例,分别代表现在和未来情景下热带气旋活动.现在情景模拟,采用1971-2000年平均的美国国家环境预报中心(NCEP)的再分析资料作为初始场和侧边界场,表示现在的气候背景;未来情景的模拟则以联合国气候变化政府间专家委员会(IPCC)第四次评估中的美国国家海洋和大气管理局(NOAA)的地球物理流体动力学实验室(GFDL)CM2.0模式模拟的A2情景下2031-2060年数据作为初始场和侧边界场,表示未来全球变暖的背景.A2情景是指在2000-2100年这100年间,对大气中的二氧化碳分子浓度由现在的380ppm增长至800ppm.结果表明,在全球变暖的背景下,热带气旋的强度明显较强,相比较现在的气候背景,在西部生成的热带气旋比东部更强些,而且未来的热带气旋的路径整体上比现在的热带气旋偏东.热带气旋活动与大尺度环流背景有密切联系,未来热带气旋在130°E以西增强,主要是由于该区域海表面温度的增高,而在试验区中南部5°N附近热带气旋减弱可能与风切变以及相对湿度的变化有关,热带气旋路径的变化则与未来西太平洋副高强度偏强、脊线偏南有关.

The mesoscale atmospheric numerical model is used to study the tropical cyclone activities in the western North Pacific under the background of global warming. Two sets of experiments are carried out to simulate tropical cyclone activities in the present and future climate, respectively. Each set of experiment includes 44 tropical cyclones. The National Center for Environmental Prediction reanalysis data averaged from 1971 to 2000 are used as initial and lateral boundary conditions for present climate, and the U. S. National Oceanic and Atmospheric Administration＇s data from 2031 to 2060, which is the result of geophysical fluid dynamics laboratory＇s CM2.0 with the A2 scenario, are used as initial and lateral boundary conditions for the future climate. The model results show that the tropical cyclones enhance significantly under global warming. Compared with current climate, the tropical cyclones generated in the west part of the Western North Pacific are stronger than those in the east part. The tropical cyclones in the future move more east than those in present. Tropical cyclone activity is closely related, to large scale atmospheric circulation. In the future, the enhancing of tropical cyclones in the west of 130°E is mainly due to the increasing of sea surface temperature in this region, and the weakening of tropical cyclones near the south of 5°N is related to the change of vertical wind shear and relative humidity in the correspond area. The change of the tropical cyclone track is related to the enhancement and the south movement of the west Pacific subtropical high.