太平洋潜热通量及其与黄淮夏季降水的关系

Latent Heat Flux over Pacific and Its Relationship with Summer Precipitation in Huanghuai Region

研究了1979—2010年太平洋潜热通量的变化特征及其与中国黄淮夏季降水的关系。结果表明，潜热通量的气候场和方差场均存在着明显的季节变化，且各季节气候场的极值中心也是变化幅度较大的区域。黄淮地区降水与前期春季的潜热场相关性最好。定义了黄淮夏季降水指数来研究影响降水的潜热场关键区，发现春季潜热关键区为10°～20°N之间的中东太平洋和热带东太平洋沿岸海区。春季当上述两个海区净潜热通量增多时，后期夏季500hPa和850hPa位势高度异常场中，在太平洋西海岸阿拉斯加南部一线上均表现为“正负正”的分布型，黄淮降水偏多。

The NCEP/NCAR reanalysis Ⅱ datasets are used to investigate the spatial and temporal variations of the Latent Heat Flux （LHF） over the Pacific from 1979 to 2010, as well as its relationship with summer precipitation in the Huanghuai region. Results show that both of the climatological and variance fields of LHF have clear seasonal changes. The extreme value centers in the climatological fields are also the regions with larg variability. In addition, the seasonal LHF fields are analyzed through EOF analysis, and it is conclued that there existed an abrupt climate change in the spring LHF field around 1997, as well as in summer. In autumn and winter, the abrupt change happened before 1995. Summer precipitation index of the Huanghuai region was defined to investigate the key areas of LHF, and it is found that pre-spring LHF fields were closely related to precipitation. Key areas of the spring LHF field were over the middle-eastern Pacific between 10°N and 20°N and the eastern tropical Pacific, and their relationships with atmospheric circulation show that when the LHF over the two regions mentioned above increases in spring, geopotential height anomaly both at 500 hPa and 850 hPa in summer over the western coast of Pacific displays a distribution pattern of ＂positive-negative-positive,＂ and there will be more precipitation in the Huanghuai region.