中国北方近50年干旱变化特征

Climate Change in Drought over Northern China during 1950-2000

根据1950～2000年我国629个站逐月降水资料,采用Z指数作为旱涝等级划分标准,根据计算出的Z指数把各地的旱涝情况划分成7个等级,并在此基础上计算了干旱发生的范围.通过研究干旱范围变化趋势和特征,进而诊断干旱发生严重程度的变化.通过对近半个多世纪来的资料进行分析,发现我国北方主要农业区不同程度的干旱面积均有扩大趋势,在不同季节以及北方区内的其它区域干旱的发生发展还有不同的特征.

Based on China's monthly precipitation data of 629 stations during 1950-2000, we calculated Z indices and separated them into seven Dryness and Wetness grades. Furthermore, a drought area index was proposed to study changes of drought extent. The results revealed that the different grades of droughts all show expanding trends in northern China's main agricultural area. Moreover, the area coverage of droughts in different seasons and different regions displayed different trends.