华南夏季降水20世纪90年代初的年代际变化及其与南亚高压关系

The interdecadal variability of summer precipitation over South China in early 1990s and its relationship with South Asia High

利用1979—2008年中国160站降水资料、NOAA的CMAP降水资料以及NCEP/NCAR大气再分析资料,应用1978—2008年全球逐月观测海表温度驱动NCAR CAM5.1全球大气环流模式进行数值模拟,探讨了华南夏季降水的年代际变化特征及其与南亚高压的关系。结果表明,华南夏季降水与南亚高压的东伸脊点关系密切,均在20世纪90年代初存在年代际转变。在1993—2008(1979—1992)年期间,南亚高压位置偏西(东),西北太平洋副热带高压位置偏东(西),华南地区则低层辐合(辐散)异常、高层辐散(辐合)异常,产生异常上升(下沉)运动,华南地区降水年代际偏多(少),这也被数值试验结果所验证。

Based on the precipitation data of 160 gauge stations in China from 1979 to 2008, CMAP precipitation data provided by NOAA and NCEP/NCAR reanalyses, simulating with NCAR CAMS. 1 model driven by global sea surface temperatures, the interdecadal variability of summer rainfall in South China and its relationship with South Asia High （ SAH ） is discussed in this study. Results show that summer precipitation in southern China and the eastward ridge point of SAH exhibit an obvious interdecadal change around the early 1990s and they are closely related each other. During the 1993-- 2008 （1979--1992） period, the position of SAH extended westward （eastward）, and the NorthwestPacific subtropical High eastward （westward）, bringing a convergence （divergence） anomaly at the lower troposphere and adivergence （convergence） anomaly at the upper troposphere over the South China, which caused a rising （sinking） motion and thus resulted in more （less） precipitation than normal in this region. These observed results are also verified by the numerical experiment results.