中国北方气候干湿变化及干旱演变特征

利用中国北方15个省(区、市)320个气象站1960—2014年逐月降水量资料,运用标准化降水指数(SPI)、标准差和相关分析等方法,基于不同时间尺度,对近55年来中国北方及不同干湿区气候干湿时空变化特征进行分析,并从干旱站次比、干旱强度等方面分析了年际干旱的时空变化特征。结果表明:(1)1960—2014年中国北方地区整体呈变干趋势,年际干旱站次比和干旱强度在同步波动中均呈下降趋势。(2)1960—2014年北方地区春季和冬季呈湿润化趋势,冬季湿润化趋势最明显,夏季和秋季呈干旱化趋势,夏季干旱化趋势最显著,夏季降水对年干湿状况的变化起决定性作用。(3)湿润区和半湿润区有干旱化趋势,而干旱区和半干旱区均呈湿润化趋势发展;湿润区和半湿润区年际干旱站次比、干旱强度呈上升趋势,而干旱区和半干旱区则相反。(4)中国北方东部季风区的湿润区和半湿润区以及处于季风区和非季风区分界线两侧的半湿润区和半干旱区气候干湿变化均呈显著同步波动变化趋势,而中国北方东部季风区的湿润区和半湿润区与中国北方西部非季风区的干旱区气候干湿变化呈显著反向波动变化趋势,夏季具有同样的规律,而冬季和春季四大干湿区干湿变化具有较好的同步一致性。

Climate dry-wet change and drought evolution characteristics of different dry-wet areas in northern China

The Standardized Precipitation Index (SPI), standard deviations, and correlation analysis methods were adopted to explore temporal and spatial characteristics of dry and wet climatic changes in northern China using monthly precipitation data for the last 55 years (1960-2014) from 320 stations across 15 provinces. Furthermore, based on the Drought stations proportion and drought intensity, temporospatial characteristics of annual drought were also studied. The results showed that:(1) From 1960 to 2014, there was a general trend of northern China gradually becoming arid. The annual Drought stations proportion and drought intensity declined simultaneously. (2) Although there was a trend of increasing wetness in both spring and winter, it was more obvious in the winter. On the contrary, summer and autumn had a trend of becoming arid, which was more obvious in the summer. Summer precipitation was a determining factor for variation in annual dry-wet patterns. (3) Humid and semi-humid areas tended to become more arid, whereas arid and semi-arid areas had a wetting trend. The Drought stations proportion and drought intensity increased in humid and semi-humid areas, but decreased in arid and semi-arid areas. (4) Dry-wet climatic changes in northern China''s eastern monsoon area (humid and semi-humid areas) and both sides of the boundaries of the monsoon area (semi-humid and semi-arid areas) had obviously synchronous fluctuation trends. However, there were opposite fluctuation trends in northern China''s eastern monsoon area (humid and semi-humid areas) and arid areas in the western non-monsoon area of northern China. Summer had the same pattern, and dry-wet changes in four dry and wet areas in winter and spring also had synchronous fluctuation trends.