黄河中游地区近522年旱涝突变

应用T检验方法对我国黄河中游地区1470～1991年夏季（5～9月）旱涝等级序列进行分析，结果表明:该地区气候存在着两次百年尺度突变，即17世纪50年代前后（旱转涝）和18世纪60年代初期（涝转正常），以及百年尺度内20～30年尺度的气候突变；并指出黄河中游地区各时期旱涝变化与赤道东太平洋海温指数（SSTI）和大气活动中心的演变有密切联系。

Abrupt Change of Drorght/Flood for the Last 522 Years in the Middle Reaches of Yellow River

The summer dryness/wetness grades series for the last 522 years (1470~1991) in the middle reaches of Yellow River are analysed by T test. The results indicate that there are two abrupt changes with 100-year scale in this region, around 1650’s (from drought to flood) and in the early 1760’s (from flood to normal). There are also jumps of 20~30 year scale within the 100-year scale variations. It is also found that the drought/flood in the region are associated with the evolution of atmospheric active centers and the Sea Surface Temperature Index (SSTI) of the equatorial East Pacific.