Abstract:

Based on monthly precipitation data from 116 meteorological stations during 1961-2012, the decadal variation, spatial distribution, periodic variation, and abrupt changes were analyzed by using the REOF, linear trend, Mann-Kendall test and Morlet wavelet analysis methods.The results show that the spring precipitation in Southwest China presented obvious regional character in recent 52 years, and the precipitation distribution in almost each decade from the 1960s to the 2000s showed an opposite change tendency in the east and the west region. So, Southwest China was divided into four regions according to the REOF of spring rainfall there. The spring precipitation inⅠarea (Yunan and southwest Sichuan) and Ⅳarea (Ganzi, Aba, Liangshan, Panzhihua) showed an increasing trend, while in Ⅱ area ( Guizhou and southeast Sichuan) and Ⅲ area (Chongqing and northeast Sichuan) it showed a decreasing trend. The spring precipitation in the four areas showed periodic variation, and the long period included short periods, which mainly were 24-28 years periods and periods shorter than 10 years. The abrupt changes of spring rainfall in the four areas were basically after the 1980s, and the obvious variation concentrated mostly during the early 21st century.

Key words:  spring precipitation, Southwest China, REOF, periodic variation

摘要：

根据1961～2012年西南地区（四川、重庆、贵州、云南）116个气象台站逐月降水资料，利用REOF、Morlet小波分析、Mann-Kendall突变检验等方法分析了西南地区春季降水的年代际变化、空间分布特征、周期变化、突变年份等。结果表明，近52 a来，西南地区春季降水有明显的地域性，从20世纪60年代到21世纪初，几乎每个年代降水都呈现东西部反相趋势。据此把西南地区春季降水进行REOF分区，可分为4个区域：Ⅰ区（云南地区和四川西南部）和Ⅳ区（川西高原和攀西高原部分地区）春季降水呈增加趋势，Ⅱ区（贵州地区和四川东南部个别地区）和Ⅲ区（四川东北部和重庆地区）呈减少趋势。4个区域春季降水都是长周期中包含着短周期，24～28 a的周期和10 a以下的周期较为普遍。4个区域春季降水突变都普遍发生在1980年代后，降水变化显著时期基本集中在21世纪初期。

关键词: 春季降水, 西南地区, REOF, 周期变化