宁夏中南部作物生长期可利用降水变化规律及其异常特征

目的]研究宁夏中南部作物生长期可利用降水变化规律及其异常特征。方法]利用1961～2010年宁夏中南部9个气象站3～9月逐月降水、气温和美国NCEP/NCAR再分析资料,采用高桥浩一郎蒸散经验公式、Mann-Kendall、Lepage法、Morlet小波分析等方法对宁夏中南部作物生长期可利用降水的变化特征及其异常特征进行分析。结果]近50年宁夏中部干旱区与南部丘陵区作物生长期可利用降水量差异明显,呈南多北少特征,2个区域可利用降水量均呈减少趋势;各年代的变化各不相同,中部干旱区70年代以后、南部丘陵区90年代以后可利用降水量持续偏少,且中部干旱区可利用降水量变率大;2个区域作物生长期可利用降水分布极不均匀,均主要出现在7、8、9月,占生长期总量的76%以上,而3、4、5月低于生长期总量的14%。中部干旱区和南部丘陵区均未出现突变现象;中部干旱区主要存在5～7年的周期,其次是2～3年的周期;南部丘陵区主要存在2～3年的周期,其次是10～12年的年代际周期。多雨年北半球欧亚500 hPa高度距平场中贝加尔湖、蒙古国和我国西北部地区为负距平区,少雨年则为正距平区。结论]该研究为宁夏中南部空中可利用水资源的合理利用提供参考。

The Variation Rule and Anomaly Features of the Available Precipitation in the Growth Period of Crops in the Middle and Southern Part of Ningxia

Objective] The aim was to study the available precipitation and its abnormal characteristics during the growth period of crops in the middle and southern part of Ningxia.Method] Through Takahashi’s evaporation equation,linear trend analysis,Mann-Kendall,Lepage,wavelet analysis,the characteristics of available precipitation and its abnormal characteristics during its growth period in Ningxia were analyzed based on monthly precipitation(March-September),temperature,and NCAR/NCEP reanalysis data in 9 observation stations from 1961 to 2010.Result] In recent 50 years,the available precipitation during the growth period of crops in central drought area and south hilly area varied a lot,more in the south and less in the north.The available precipitation in these two areas was reducing and varied a lot in different ages.The available precipitation was less in the middle drought region after 1970s and in the southern hilly region after 1990s and the available precipitation in middle drought area changed significantly.The available precipitation in the two areas appeared in July,August,and September,above 76% of general growth period,while that in March,April and May was 14% lower than that in growth period.No abrupt changes in central drought area and south hilly area.There were the periods of 5-7a and 2-3a oscillations in the middle drought region,2-3a and 10-12a oscillations in the southern hilly region.There were negative anomaly field at 500hPa height in high-precipitation years between the Baikal and the China’s northwestern,and there were positive anomaly field in low-precipitation years.Conclusion] The study provided reference for the reasonable utilization of available water resources in middle and southern Ningxia.