近45a宁夏气温、降水及植被指数的变化分析

利用1961~2005年宁夏气温、降水资料,并结合1982~2003年植被指数(NDVI)数据,分析了宁夏气温、降水和NDVI的时空变化特征。结果表明:近45a来,宁夏气温明显升高,降水总体呈减少趋势;冬季和引黄灌区升温最明显,冬季降水增加,其它季节及各地区降水减少,其中秋季和宁夏南部山区减少最明显;秋冬季降水在1968年前后发生了突变,突变后,冬季降水增多,秋季降水减少;1985~1996年间发生了气温突变,突变后各季及各地区气温明显升高,冬春季和引黄灌区降水增多,其它季节和地区降水减少,极端气候事件较突变前发生更为频繁;近20a宁夏区域内NDVI值呈增加趋势,荒漠化面积整体得到控制。进一步分析表明,前一年气温偏高、夏季降水增加时,有利于当年NDVI值增加。

Change of Temperature, Precipitation and NDVI in Recent 45 Years in Ningxia

Using the data of precipitation and temperature covering 1961-2005 in Ningxia and combining them with data of NDVI covering 1982-2002, the spatio-temporal characteristics and response of precipitation, temperature and NDVI in Ningxia to global warming were analyzed. The result showed that in recent 45 years, there was evident rise in temperature but decrease in precipitation as a whole in Ningxia. There were also evident differences in seasonal and regional temperature and precipitation. Temperature in winter and the areas by diverting Yellow River water for irrigation rose most evidently. Precipitation increased in winter but reduced in other seasons and areas. Especially precipitation in autumn and southern Ningxia mountainous area reduced most evidently. There was a rainfall break in winter and autumn around 1968, and after the break rainfall in winter increased but reduced in autumn. There was also a temperature break during 1985-1996. After the break, temperature rose evidently throughout Ningxia and rainfall in winter and spring and the areas by diverting Yellow River water for irrigation increased but reduced in other seasons and areas. Extreme climate events happened more frequently. The value of NDVI showed an increasing trend and the desertified area was controlled on the whole. Further analysis indicated that when temperature was high and precipitation increased in summer in the previous year, NDVI of present year would increase.