影响长江中下游夏季降水的前期潜在预报因子评估

利用1951～2006年美国NOAA海温资料、NCEP/NCAR再分析资料和青藏高原雪深等资料,根据前期海—陆—气因子对夏季长江流域降水的影响,本文搜集并整理了影响长江中下游夏季降水的40个预报因子,并讨论了前期因子与夏季降水在不同阶段的相关稳定性.通过相关和历史回报方法,讨论了前期关键因子与东亚夏季大气环流之间的关系...

Evaluations of Prior Potential Predictors for the Summer Rainfall in the Middle and Lower Reaches of the Yangtze River

In the framework of impacts of sea-land-atmosphere factors on the following summer rainfall in the middle and lower reaches of the Yangtze River (MLYR), the authors reconstructed 40 factors on the basis of sea surface temperature (SST), snow depth in the Tibetan Plateau, and NCEP/NCAR reanalysis datasets, and evaluated their possible impacts on the summer rainfall in the MLYR. Firstly, the authors discussed the stability of relationships between these factors and the following summer rainfall in the MLYR before and after 1979. Secondly, the authors selected several important factors by correlation analysis, and discussed the relationship between these factors and East Asian summer monsoon (EASM). In addition, the potential forecast capability of these factors for the summer rainfall in the MLYR was discussed by historical hindcasts. The results suggest that the important winter predictors for the summer rainfall in the MLYR mainly come from the external forcing, such as the SST in Niño3 and Kuroshio Current regions, and the snow depth in Tibetan Plateau. In contrast, the potential spring predictors are almost the general circulation indices, such as Arctic Oscillation (AO), polar vortex, and the western North Pacific subtropical high (WNPSH). Running correlations between these potential predictors and the summer rainfall in the MLYR vary on interdecadal time scale, however, the SST in Kuroshio Current region, the snow depth in the Tibetan Plateau, and the surface air temperature near Lake Baikal show the significant antecedents for summer rainfall in the MLYR by affecting the EASM circulations, and jointly suggest the better forecast capability for the rainfall anomaly in the MLYR after 1979.