运用1979-2014年长江下游逐日降水量数据(25个站点的平均值)和NCEP/NCAR全球850 hPa纬向风格点再分析数据(2.5o×2.5o),经过经验正交函数(EOF)和奇异谱分析(SSA),得到用于构建扩展复数自回归模型(ECAR)的次季节预测实验数据集。对2001-2014年长江下游降水低频分量进行次季节逐日变化回报试验的结果表明,50-80 d时间尺度的长江下游低频降水分量的预测时效可达52 d左右,预报能力明显优于自回归模型(AR),而且6-8月的预报技巧最高?该数据集包括1979年1月1日-2014年12月31日全球850 hPa 50-80 d低频纬向风场的7个低频主成分pc1,pc2,…,pc7和长江下游地区逐日低频降水(the daily low frequency rainfall in the lower reaches of the Yangtze River Valley,lcjr)的时间序列(序列长度是13,149 d)。数据集存储在Excel文件,数据量1.19 MB。
Observational and reanalysis data are used to investigate the different relationships between boreal spring sea surface temperature (SST) in the Indian and Pacific oceans and summer precipitation in China. Partial correlation analysis reveals that the effects of spring Indian Ocean SST (IO SST) and Pacific SST (PSST) anomalies on summer precipitation in China are qualitatively opposite. When IO SST anomalies are considered independently of PSST anomalies, precipitation decreases south of the Yangtze River, in most areas of Inner Mongolia, and in some parts of Liaoning Province, and increases in the Yangtze River valley, parts of southwestern and northern China, northeastern Inner Mongolia, and Heilongjiang Province. This results in a negative-positive-negative-positive pattern of precipitation anomalies in China from south to north. When PSST anomalies (particularly those in the Nin o3.4 region) are considered independently of IO SST anomalies, the pattern of precipitation anomalies in China is positive-negative-positive-negative from south to north. The genesis of summer precipitation anomalies in China is also examined when El Nin o-Southern Oscillation (ENSO) signals are removed from the ocean and atmosphere. An anticyclonic low-level wind anomaly forms in the South China Sea-Northwest Pacific area when the IO SST anomaly (SSTA) is warm and the Northwest Pacific SSTA is cold. This anticyclonic anomaly substantially influences summer precipitation in China. Anomalous warming of tropical IO SST induces positive geopotential height anomalies in the subtropics and an east-west dipole pattern in midlatitudes over Asia. These anomalies also affect summer precipitation in China.
