北美和欧亚大陆冬季快速增温与地表干湿变化

Enhanced Winter Warming in North America and Eurasia and Its Correlation with Dry/Wet Variation at the Surface

采用东英吉利大学气候研究中心(CRU)提供的月地表温度和降水资料,分析了全球年平均及冬季地表温度变化趋势,发现在北半球中高纬地区半干旱区冬季快速增温。在此基础上通过分析帕默尔干旱指数(PDSI)研究了北美和欧亚大陆冬季地表干湿变化的时空特征和差异,并讨论北美和欧亚大陆冬季快速增温对地表干湿变化的影响。结果表明,北美大陆南部微弱变湿,加拿大北极群岛变湿明显,而在北美大陆的中西部有明显的变干趋势;欧亚大陆大部分地区在冬季有一定的变干趋势,其中尤以西欧南部,中国华北、东北,蒙古中北、东北部及俄罗斯远东地区变干最为显著。但北美和欧亚大陆1950—2008年冬季降水并无显著变化趋势,地表干湿变化主要受气温的影响,尤其是在冬季增温最为快速的地区。

This study examined surface air temperature trends over global land in 1901-2009 using data（monthly precipitation and monthly mean surface air temperature） from Climatic Research Unit（CRU） at University of East Anglia.It is found that the warming trend was particularly enhanced in the winter seasons over semi-arid regions at mid-high-latitude areas.By analyzing the temporal and spatial characteristics of dry/wet variation at the surface of North America and Eurasia and the impact of enhanced winter warming upon the dry/wet variation,it is found that the south of North America was becoming wet weakly and Arctic Archipelago in Canada became wet apparently while the middle and west of North America was drier.In Eurasia,most of the continent became drier,especially in the south of West Europe,North China,Northeast China,the central-north and northeast of Mongolia and far east of Russia.But there was no clear trend of precipitation in North America and Eurasia during the winter seasons in 1950-2008,so the dry/wet variation was mainly affected by the change of temperature,especially in the places where winter warming was enhanced.