近50年陕北地区的气候变化

Analysis on Climate Change in North Shaanxi Province

通过累积距平法、Mann-Kendall法和Morlet小波分析等方法,对陕北地区近50年来的气候变化多尺度和跃变(突变)现象进行了分析。结果表明:近50年来,陕北地区年平均气温有上升趋势,变化倾向率为0.296℃/10 a,年平均气温在1994-1995年发生了由低温到高温的突变;陕北地区年降水量呈下降趋势,变化倾向率为-12.455 mm/10 a,年降水量在1974-1975年和2000年都发生了由少到多的突变。Morlet小波分析表明,陕北年平均气温存在25年的强显著周期,此外还有4年、5～10年不等的小尺度周期变化;陕北年降水存在24年、7年、5年和3年的显著周期,且大周期尺度比小周期尺度更为显著。陕北气候暖干化的原因主要是海-气相互作用的大气环流因子,此外,城市化因素对气候的影响也应引起重视。

Global warming has become evident since the last years of the twentieth century,and the climate in Shaanxi Province is affected by it in varying degrees.Based on the monthly data of temperature and precipitation during the period 1960-2008,this paper analyzes the sharp climate change at multi-time scales in north Shaanxi Province using the cumulative anomaly,Mann-Kendall test,Morlet wavelet analysis,etc.The results show that there was a significant climate warming trend with a temperature increase of 0.296 ℃/10 a in north Shaanxi Province,and a sharp change from low temperature to high temperature occurred during the period 1994-1995;annual precipitation was in a decrease trend,its linear trend rate was-12.455 mm/10 a in recent 50 years,and the sharp change from precipitation decrease to increase occurred in the mid-1970s and 2000.The Morlet wavelet analysis was used to analyze the change periods of annual temperature and precipitation.The results reveal that the annual temperature fluctuated significantly with periods of 25 years,4 years and 5-10 years,and the annual precipitation fluctuated with periods of 24 years,7 years,5 years and 3 years,respectively,especially at large time scale.The atmospheric circulation factors of air-sea interaction are the main causes resulting in climate change towards warming-drying pattern in north Shaanxi Province,and the effect of urbanization on climate change should be paid more attention.