黄河中游地区近522年旱涝突变

ABRUPT CHANGE OF DRORGHT/FLOOD FOR THE LAST 522 YEARS IN THE MIDDLE REACHES OF YELLOW RIVER

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（早转涝）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．

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.