全球增暖背景下中国干湿气候带变化规律研究

用中国区域561个气象站1961—2010年的逐日气象资料,计算了多时间尺度的湿润指数。用ArcGIS软件平台对站点的降水量和湿润指数进行反距离加权插值,得到其空间分布图,进而分别从全球气候变暖背景下和年代际两个角度分析了湿润指数与干湿气候带界线的变化特征。结果表明:在气候变暖背景下,新疆的极干旱区范围缩小;内蒙东部半干旱区东伸增大,西部干旱区南移扩大;山东半湿润区南移扩大;陕西半干旱区加大,湿润区缩小。从年代际变化而言,湿润指数和干湿气候带界线分布有明显的区域特征。东北地区总体呈现干湿交替特征;1970s起,西北地区总体趋湿;华北东南部持续趋干;新疆南部(极干旱区)持续趋湿;南方地区在2000s四川南部和贵州中南部趋干,出现部分半干旱区。另外,根据中国农业区划方案,分别计算7个一级农业类型区湿润指数。发现7大农业区50 a来湿润指数都呈下降趋势(青藏区除外),尤其西南地区在2000s湿润指数下降最为显著,其主要原因是2001年以来该地区潜在蒸散增加和降水偏少造成的。

Variation laws of wet and dry climatic zones in China under global warming

Wetness indexes of multiple time scale are calculated by 40a (1961-2010) daily observation data from 561 meteorological stations in China. According to spatial distribution maps of precipitation and wetness index drew by ArcGIS, this paper analyzed variation of wetness index and boundary line of dry-wet climatic zones. The results indicated that under global warming, the scope of extremely-arid zone in Xinjiang shrinked; semi-arid zone of easterr Nei Mongol expanded eastward; semi-humid zone of Shandong expanded southward; semi-arid zone in Shanxi expanded but humid zone shrinked. The boundary lines of wet-dry climatic zones had apparent interdecadal features: the wetness index of northeast China fluctuated; since 1970s, northwest China has been wet on the whole, while southeast part of north China became continually dry and the south part of Xinjiang became continually wet; in the first 10 a of 21st century, southern Sichuan and south-central region of Guizhou were partially wet. Furthermore, wetness indexes of 7 first-order agricultural regions were calculated based on Chinese agricultural regionalization, whose result indicated that these wetness indexes were all on the decline except that of Qinghai-Tibet Plateau. The wetness index of southwest China in the first 10 a of 21st century declined markedly, the main reason for which was that potential evaporation increased while precipitation decreased since 2001.