近49年华南“龙舟水”的降水分型

Precipitation Patterns During the "Dragon Boat Water" in South China for the Recent 49 Years

采用旋转经验正交函数分解法（REOF）对华南地区1961—2009年“龙舟水”进行了降水分型，并采用线性倾向估计法、经验模态分解（EMD）、Morlet小波分析和Mann—Kendall检测等分析方法对各降水型的时空特征进行了研究。结果发现：华南“龙舟水”具有东南沿海型、北部型和西南沿海3种优势降水型，并存在着6--8a的周期振荡。近49年东南沿海型（北部型和西南沿海型）呈现一致的下降（上升）趋势，华南“龙舟水”在20世纪90年代中期至今主要呈现北部型，但近几年东南沿海型和西南沿海型对应显著正距平。东南沿海型和北部型分别在20世纪70年代中后期和90年代初各有一次突变，而西南沿海型没有发生明显的突变。最后，从西太平洋副热带高压、阻塞高压、季风槽、低层切变线、垂直速度和整层水汽输送等方面对比了“龙舟水”期间3种不同降水型所对应的大气环流异同。

Based on the rotated empirical orthogonal function （REOF） method, the precipitation patterns during the ＂Dragon Boat Water＂ from 1961 to 2009 are analyzed. What＇s more, the spatial and temporal characteristics are discussed by adopting linear tendency estimation, experimental mode decomposition （EMD）, Morlet wavelet analysis and Mann-Kendall test. The results show that there are three kinds pre- ferred precipitation patterns in Southeast Coast, the North region and Southwest Coast, respectively, and all of them show 6--8 year periodic oscillations. Southeast Coast has decreasing trend in precipitation, while the North region and Southwest Coast share an increasing trend in the past 49 years. However, the precipitation ＂dragon boat water＂ has occurred more frequently in the North region since mid 1990s, and the rainfalls in Southeast and Southwest Coast have shown positive anomalies in recent several years. Two abrupt jumps occurred in mid 1970s and early 1990s in Southeast Coast and the North region, respectively, but there was no obvious change in Southwest Coast. Finally, the different atmospheric circulation fea- tures are compared from the aspects of Northwest Pacific subtropical high, blocking high, monsoon trough, low layer shear, vertical velocity speed and the total water vapor transport.