中国黄土高原地区4～10月雨量时空变化特征分析

Analyses on Spatial-Temporal Change Characteristics of Rainfall over Chinese Loess Plateau from April to October

利用黄土高原区域40年的实测降水资料，研究了该区作物生长期（4～10月）降水量的时空变化特征，并对于年和湿年的降水进行了分析和比较。结果表明：黄土高原作物生长期降水在1985年左右发生突变，由历史上的多雨转为少雨；降水异常变化存在3～5年、8年左右和11～16年左右的振荡周期，3～5年的振荡周期更明显；干湿年降水存在明显差异，湿年比干年多40％以上；存在降水异常响应的敏感区，干旱在高原的东北部响应变幅大于其它地方，湿涝响应在高原的北部最为明显。

Using the observed precipitation data over Chinese Loess Plateau from April to October in recent 40 years, the spatial-temporal changes of the rainfall are studied, the distributions of precipitation anomaly in dry and wet years are analyzed as well. The results show that the rainfall over Chinese Loess Plateau in April-October appeared an abrupt change in 1985 or so, and since then on the more rain year change into less rain year. The wavelet analysis shows that the anomalous changes of precipitation had 3 5, 8 and 11-16 year oscillation periods, but 3-5 year periods were more obvious. There were three sensitivity regions of anomalous precipitation over Chinese Loess Plateau, and two phases appear obvious in the years of 1985. The rainfall amount in dry and wet years had obvious difference, and the one of wet year was more 40% than that of dry year. The differences of dry and wet years were remarkable. Also, the dry year occur easier in the northeast of Chinese Loess Plateau, and wet year, in north.