从气候标准的改变分析西北地区的气候变化

利用中国西北地区122个气象站旬降水量和平均气温资料，比较了1960-1990年与1970-2000年气候标准的差异，并由此分析了西北地区气候变化的地域特征。说明西北地区在气温显著升高的同时，西部降水增加，由暖干向暖湿转型的事实，但是西北地区东部干旱的形势比前期更加严峻。西北地区30a气候标准的差异，主要是由于20世纪60年代与90年代气候状态的显著差异造成的。新气候标准的应用对于气候统计分析、评价和预报产生重要影响。

Analysis on the Climate Change from Warming-drying Trend to Warming-wetting Trend in Northwest China

In this paper,the difference of climate change in northwest China during the periods of 1960-1990 and 1970-2000 is compared based on the data of ten-day precipitation and air temperature observed by 122 meteorological stations in northwest China,and the regional characteristics of climate change are analyzed.The results are as follows:(1) Precipitation increases in the western part of northwest China,especially in Xinjiang,but it decreases in the eastern part of northwest China,especially in Shaanxi Province.Therefore,the anomaly of precipitation decreases in the western part of northwest China but increases in the eastern part of northwest China.The precipitation in the recent 30 years has increased comparing with that in early 30 years,especially during the period from December to next early spring.The precipitation increases in some regions but decreases in some other regions in the northwestern part of northwest China;(2) The average ten-day air temperature has been significantly increased since recent 30 years comparing with that in early 30 years,which will result in a reduction of the anomaly of air temperature.The temperature increase is the most significant in winter;(3) The average values of both precipitation and air temperature in northwest China during the period of 1960-1990 were significantly different comparing with that during the period of 1970-2000 due to the difference of climate status in the 1960s and 1990s.The difference of the average precipitation in northwest China was mainly caused by the precipitation reduction in the 1990s,and that of average air temperature was mainly caused by the temperature decrease in the 1960s and the temperature increase in the 1990s.The difference of average climatic values will affect significantly the meteorological statistics,analysis,evaluation and prediction.