渭北旱塬气温变化及对小麦生产的影响

利用陕西渭北旱塬12个气象站1960—2007年各月平均气温资料,计算月、季、年平均气温异常偏高和偏低出现频次,并分别对其时空分布特征和演变规律进行了分析。最后对农业生产的影响作了分析。研究表明:(1)渭北旱塬近48年来气温呈现明显的增暖趋势,这与全球气温增暖趋势一致。季节增暖程度差异明显,冬季增暖最为显著,其次为春季,夏季增暖趋势最不明显。冬季气温增暖,将会使小麦安全越冬北界向北移动。随着气温增高蒸发量加大,旱灾更加严重;(2)1960年以来渭北旱塬月平均气温异常偏高出现频率最大的在8月份,6月份没有发生过气温异常偏高。气温异常偏低在频率最大在2月份,5月是一年中唯一未发生气温异常偏低的月份;(3)季气候变暖,冬温偏高,增加了冬季农田土壤水分蒸发,还使越冬病虫卵蛹死亡率降低,病虫群数量上升,易造成小麦病虫害,增大了病虫害防治难度,气温上升带来了不利影响;(4)渭北旱塬冬季和春季气温异常偏高从20世纪90年代开始明显增加,秋季气温异常偏高出现的频数相对稳定,冬季气温异常偏低明显减少,使小麦冻害减少。

The Temperature Change and Its Influences on Agricultural Production in Weibei dryland

This paper used the data of average temperature that came from 12 weather stations from 1960 to 2007 to calculate the frequency of abnormal average temperature in Weibei dryland, and analyzed the distribution characteristics and evolution rules of abnormal average temperature. It also analysed the influence on agriculture production. The research showd that： （1） Temperature had been on the rise in the past 48 years, which was consistent with the trend of global warming .The warming levels in different seasons were sharply different. Among the four seasons, winter warming was the most evident, followed by spring. Summer warming was not so apparent. With the rising of temperature in winter, the safely growing area of wheat in winter would move further to the north. What＇s more, the drought would be more serious as the evaporation increased. （2） Abnormal warming phenomenon always happened in August since 1960 in Weibei dryland, and never happened in June. Abnormal chilling appeard to be in February. May was the only month that had not witnessed exceptionally low temperature. （3） The seasonal warming led to the rise of winter temperature. It increased soil moisture evaporation of farmland in winter and in the meantime also made across-winter pest eggs and pupas ＇ mortality decrease. Therefore, it tended to be more difficult to control pest. They were the adverse effects of rising temperature. （4） Weibei dryland ＇ s abnormally high temperature had been moreobvious since 1990s. The frequency of abnormally high temperature in autumn was stable. And the frost damage to crops had been reduced as the abnormally low temperature in winter reduced obviously.