1901-2012年陕西降水、气温变化特征

利用英国东英格兰大学气候研究中心CRU最新发布的1901-2012年的月平均气候资料,分析陕西近百年降水、气温的时空分布特征。结果表明:(1)年平均降水南北差异较大,陕南降水多且年际变化最大,西安为年际变化的第二高值中心。(2)陕西降水具有明显的年代际变化周期,20世纪40年代之前降水变化较平缓,40年代后降水变化幅度变大,异常偏多或偏少的年份较多。(3)降水的EOF1表现为整体的正异常,体现了陕西年平均降水的一致变化,EOF2主要表现为陕西南部和陕西东北部的反相位振荡,且具有显著年际变化周期。(4)陕西气温近112年有两个偏冷期:20世纪20年代之前和50年代到90年中期,20世纪20年代到50年代和90年代后期以来为偏暖期。与全国气温变化不同,第二个暖期是从90年代开始迅速升温,滞后于全国气温变化,且气温的最高值出现在90年代而不是40年代。(5)气温的第一模态解释了总模态的88.4%,且表现为陕西一致的正异常,表明陕西平均气温空间变化的一致性,Morlet小波分析显示其有2~4年的周期震荡和16年左右的年代际变化周期。

Variation Characteristics of Precipitation and Air Temperature from 1901 to 2012 in Shaanxi,China

Using average monthly climate data released by CRU(Climate Research Unit of The British East England University) from 1901 to 2012, we analysed the temporal and spatial distribution of precipitation, and air temperature in Shaanxi during the last 100 years.(1)There is a big difference of average annual precipitation in different areas, with abundant precipitation and the maximum interannual variations in the south Shaanxi, and the second largest interannual variations in Xi'an.(2)There is an obvious interdecadal change of precipitation in Shaanxi, rainfall changes slowly before 1940s, the range of variation becomes larger after 1940s and there are many years with too much or too little rain.(3)EOF1 of precipitation change EOF analysis shows the overall positive anomaly of precipitation, showing the consistent variation of annual precipitation in Shaanxi, while EOF2 of precipitation change EOF analysis shows significant interannual cycle, showing anti phase oscillation in the south Shaanxi and in the northeast Shaanxi.(4)There is 2 periods which are much colder before1920s and from 1950s to the middle 1990s. It is much warmer from 1920s to 1950s and after 1990s. Different from the air temperature change in the whole country, the second warmer period sharply began from 1990s, lagging behind the national climate change. Besides, the maximum temperature appeared not in 1940s but in 1990s.(5)The first air temperature mode explained 88.4% of total mode, showing consistent positive anomaly and the consistency of the spatial variation of average temperature in Shaanxi. Morlet Wavelet analysis shows 2-4 years periodic oscillation of air temperature and interdecadal change cycle of about 16 years.