宁夏河东沙地气候变化对全球变暖的响应

Response of climate change in Hedong sandy area of Ningxia to global warming

利用贺兰山近百年来树木年轮指数与宁夏河东沙地代表站降水量距平/气温距平间的相关关系,反演了沙地代表站1981年以来的逐年降水量序列和1916年以来的气温距平序列,分析了河东沙地近百年来气候变化对全球变暖的响应。结果表明,500年旱涝变化周期的低频特征比较显著,其中以250年最显著,其次是60年和30年周期;河东沙地20世纪30年代中期到50年代中期是一个典型的暖湿期,这与全国平均状况的温湿时段比较吻合,但增暖的持续时间比全国平均状况延长了约10年左右。20世纪50年代中期以后气温下降,但年降水量仍然持续偏多,是一个典型的寒冷湿润时期,这一气候态一直持续到60年代末期,其后到80年代中期气温偏低,降水偏少,气候处于一个相对干冷时期,这种变化与全国平均状况的变化非常相似,但20世纪80年代中期至今河东沙地气温仍偏高,降水持续偏少,没有出现明显的回升,与全国1990年后年降水量略多的变化有所差别;河东沙地四季气温均在波动中出现了不同程度的上升,且均高于全国的平均升温速率;四季降水量在波动中有升有降,夏季存在着比较明显的上升趋势;秋季的下降速率是四季中最快的,这种趋势与全国秋季降水量下降趋势比较吻合。

By use of correlation between the drought-waterlogging grade index of Ningxia in recent 500 years/the tree ring index of Helan Mountain area and the yearly precipitation in representotive stations of Hedong sand area/ air temperature anomaly, the yearly precipitalion series of representative stations in sand area since 1981 and the air temperature anomaly series since 1916 were inversed, and the response of climate change in Hedong sand area to globle warming was analysed. Results show that, the low frequency features of the drought-flood cycle in last 500a is relatively clear, among them, that of the 250a is the most significant following with 60a and 30a. From the middle of 1930s to the middle of 1950s there is a typical warm-wet time that is consistent with the average state of the whole country, but the duration is longer than the average for about 10a. Since then, the temperature dropped and the rainfall kept above normal, that means a typical cold-wet period, and it lasted until the end of 1960s following a relative cold-dry time, at that time it is similar to the average of the whole country. Up to now since the middle of 1980s, the temperature has been keeping high with less precipitation that is different from the situation of the whole country featured with more precipitation after 1990. The temperatures in the four seasons rise in fluctuation with different ranges, and all of them are higher than that of the average of whole China. The precipitations in the four seasons changed differently in fluctuation; there is a remarkable rise in summer and the most significant decline in autumn that is consistent with the trend of the whole country.