摘要
利用1960—2004年我国586个气象站的逐日降水观测资料,对每个季节和每个站点,以雨日降水量升序排列的第90个百分位值定义极端日降水阈值,分析揭示了我国四季极端雨日数的时空变化特征、与海表温度异常的关系以及相联系的大气环流异常型。结果表明,我国长江流域极端雨日数在冬季和夏季呈显著增加趋势,华北地区极端雨日数在冬季显著增加、而在夏季显著减少,华南地区极端雨日数在春季显著增加,东北地区极端雨日数在冬季和春季显著增加,而西北地区极端雨日数在四季均显著增加。各季极端雨日数在线性趋势变化之上表现年际和年代际变化特征,并且其典型异常型明显不同,春、秋季表现为长江以南与以北地区反位相的"偶极型"变化,夏季表现为长江流域与华南、华北地区反位相的"三极型"变化,冬季表现为全国大部分地区同位相的"单极型"变化。我国季节极端雨日数与印度洋-太平洋海表温度异常的关系主要表现为与ENSO的关系,而ENSO影响我国极端降水异常是通过相应的大气环流异常型来实现的。
With daily precipitation records at 586 stations in China for 1960--2004, this study investigates the spatio-temporal variation of the number of extreme wet days （NEWD） for each season in China and its relationship with SST anomalies and associated atmospheric circulation anomaly patterns, in which a threshold of extreme precipitation for a season and a station is defined as the value of the 90th percentile when the precipitation records for wet days during the season are ranked ascendingly. Results show that there are significant increases of the NEWD along the Yangtze River Valley during winter and summer, in North China during winter, in South China during spring, in Northeast China during winter and spring, and in Northwest China throughout the seasons, while there is a remarkable decrease in North China during summer. Besides the linear trend, the NEWD also exhibits considerable interannual and interdecadal variabilities. After eliminating the linear trend, the NEWD anomalies show distinct seasonal patterns. The NEWD anomalies are characterized by a ＂dipole＂ mode between the north and south of Yangtze River valley in spring and autumn, a ＂tripole＂ mode between Yangtze River valley and South and North China in summer, and a ＂monopole＂ mode over most of China in winter. The relationship of the NEWD anomalies in China with the SST anomalies in Indian and Pacific Oceans is found to be mainly dependent of the ENSO, and associated atmospheric circulation anomaly pattems for the ENSO＇s impact on the NEWD in China are identified.
出处
《热带气象学报》
CSCD
北大核心
2012年第3期311-320,共10页
Journal of Tropical Meteorology
基金
973项目(2010CB428504)
国家自然科学基金项目(40730953
40805025)
公益性行业(气象)科研专项(GYHY200806004
GYHY200706005)
江苏省自然科学基金创新学者攀登项目(BK2008027)共同资助
