洞庭湖流域冬季降水的时空变化及与全球海温的关系

论文基于1961-2015年洞庭湖流域96个气象站点逐月降水数据和英国哈德莱中心月平均海表温度资料,利用EOF、Morlet小波和偏相关分析等方法,对洞庭湖流域冬季降水的时空变化和周期特征进行分析,并探讨影响流域冬季降水的关键海区及其关键时段。结果表明：在年际时间尺度上,洞庭湖流域冬季降水主要存在全区一致型、南北反向型和中部-南北部反向型3个模态,各模态分别具有12 a、16 a和7 a左右的长周期以及3 a左右的短周期。在与全球海温的关系方面,流域冬季降水与ENSO和南海海温均存在显著相关,平均而言,在ENSO处于暖位相或南海海温偏高时,流域冬季降水易偏多,反之,则流域冬季降水易偏少;但ENSO和南海海温对流域冬季降水的影响范围及其关键时段存在明显差异,其中ENSO的影响范围主要分布在流域南部,其在前期10月与流域冬季降水相关性最好,而南海海温的影响范围集中在流域东部,其在次年2月与流域冬季降水相关性达到最高。

Temporal and Spatial Variation of Winter Precipitation over Dongting Lake Basin and Its Relationship with Global Sea Surface Temperature

Based on the monthly precipitation data of 96 meteorological stations from 1961 to 2015 in the Dongting Lake Basin and monthly mean sea surface temperature (SST) dataset from Met Office Hadley Centre, the temporal and spatial variation and periodic properties of winter precipitation were analyzed with the methods of empirical orthogonal function (EOF), Morlet wavelet and partial correlation analysis. We also discussed the key areas and key periods which influence winter precipitation over Dongting Lake Basin. The result of EOF method showed that there were three leading modes of winter precipitation at inter-annual temporal scales: the mode being consistent over the whole area, the mode of opposite relationship between south Dongting Lake Basin and north Dongting Lake Basin, the mode of opposite relationship between central Dongting Lake Basin and south/north Dongting Lake Basin. Each mode has long periods of 12 a, 16 a, 7 a and short period of 3 a, respectively. With respect to the relationship between winter precipitation over Dongting Lake Basin and global SST, winter precipitation had a good relationship with El Niño-Southern Oscillation and South China Sea SST. On the average, when ENSO is in warm phase or South China Sea SST is higher than normal years, winter precipitation over Dongting Lake Basin is likely to be more. Reversely, winter precipitation over Dongting Lake Basin is likely to be less when ENSO is in cold phase or South China Sea SST is lower than normal years. However, there were distinct differences between the areas and key periods affected by ENSO and South China Sea SST. ENSO mainly affects south Dongting Lake Basin, and it has the best correlation with winter precipitation over Dongting Lake Basin in preceding October. South China Sea mainly affects east Dongting Lake Basin, and South China Sea SST has the best correlation with winter precipitation over Dongting Lake Basin at next Feburary.