摘要
我国南方地区各季节降水异常主要包含三种优势模态:长江及其以南地区降水呈整体偏多或偏少的一致型,长江中下游流域与华南呈反相变化的南北反相型以及东南与西南呈反相变化的东西反相型。其中一致型是南方地区各季节降水变率的第一优势模态。总体而言,在1961—2013年南方地区平均降水存在明显的年代际和长期趋势变化。其中,夏季和冬季南方区域平均降水具有相似的年代际变化特征,而秋季降水的年代际演变几乎与上述两个季节的相反。不过,在近30年南方各季降水量发生年代际转折的时间不尽相同:春季和秋季降水分别在21世纪初期和20世纪80年代中后期之后进入干位相,冬季和夏季降水则分别在80年代中期和90年代初期之后进入湿位相。自21世纪初期以来,南方夏季和冬季降水逐渐转入中性位相。此外,南方春季和秋季降水均呈减少趋势;而夏季和冬季则相反,均呈增多趋势。对于西南地区,除了春季外,其他三个季节的降水均呈减少趋势,出现了季节连旱的特征,尤其是秋旱最为严重。不过,不管是季节降水量还是旱/涝日数,在我国南方大部分地区其线性变化趋势并不十分显著,这与南方降水年代际分量对降水变率存在较大贡献相关。分析还发现,我国南方区域洪涝受灾面积具有比较明显的年代际变化,而干旱受灾面积则没有明显的年代际变化特征,近十多年来西南地区干旱和洪涝受灾出现了交替互现的特点。
The variability of seasonal-mean precipitation in southern China exists in three dominant modes:the first leading mode features consistent precipitation variation nearly over the whole part of southern China.The other two leading modes describe an out-of-phase relationship of precipitation anomalies between the middle and lower reaches of the Yangtze River Basin and the south of the basin and between the southeast and southwest China,respectively.The regional-averaged precipitation in southern China is characterized by obviously interdecadal and long-term changes in all the four seasons,of which the precipitation in summer has similar interdecadal changes with that in winter but contrasts with that in autumn during 1961— 2013.Additionally,the interdecadal temporal turning points of precipitation anomalies are different in different seasons in the recent three decades.The spring and autumn precipitation anomalies enter into dry phase after the early 2000 s and the mid-late 1980 s,respectively,while the winter and summer precipitation anomalies go into wet phase after the middle 1980 s and early 1990 s,respectively.The summer and winter precipitation anomalies gradually become neutral since the early 2000 s.Furthermore,the regional-averaged precipitation in southern China shows a decreasing trend in spring and autumn,but an increasing one in summer and winter during 1961 — 2013.In southwest China,precipitation decreases in all the four seasons except spring,and,in particular,the decreasing trend is the most remarkable in autumn.However,the linear trends of seasonal-averaged precipitation and drought/flood days are not so significant in most parts of southern China,because the interdecadal component has a relatively important contribution to the precipitation variability in southern China during this period.Finally,the results shows that interdecadal component has great(weak) contribution to the variability of total area affected by flood(drought) disaster in southern China,and in southwest China,the variability
出处
《气象》
CSCD
北大核心
2015年第3期261-271,共11页
Meteorological Monthly
基金
国家重点基础研究发展计划(973计划)(2013CB430203)
公益性行业(气象)科研专项(GYHY201306033)
国家自然科学基金项目(41205058)共同资助
关键词
南方旱涝
时空格局
旱涝受灾面积
年代际变化
长期趋势
drought/flood in southern China
spatio-temporal distribution
area affected by drought/flood disaster
interdecadal change
linear trend
