摘要
利用海洋混合层海温热量收支诊断方法和两套海洋同化再分析资料,对比分析典型拉尼娜事件和1988—1989年特殊拉尼娜事件生命史演变成因。研究结果表明,典型拉尼娜事件在发展年冬季到达最强值后通常缓慢衰减,在次年秋季时再次增强形成第二次拉尼娜事件。而1988—1989年拉尼娜事件在发展年底时到达最强值后迅速衰减,并在次年秋季时依然维持衰减过程,最终回到气候平均态。诊断分析结果表明,风场强迫作用引起的纬向异常平流项变化是导致衰减年中两种类型拉尼娜事件海温变化倾向差异的主要原因。在典型拉尼娜事件衰减时期,西北太平洋上空以异常反气旋性环流为主,反气旋性环流南侧东风距平会激发海洋上翻Kelvin波向东传播,阻碍拉尼娜事件的衰减。而在1988—1989年特殊拉尼娜事件中,西北太平洋上空以异常气旋性环流为主。异常气旋性环流南侧西风距平将激发海洋下沉Kelvin波向东传播,引发海洋中自西向东的纬向异常暖平流帮助拉尼娜事件迅速衰减,最终回复到气候平均态。
The physical mechanisms which caused the distinctive evolution features of the 1988 to 1989 La Niña Event were investigated suing an oceanic mixed-layer heat budget analysis method which incorporated two sets of ocean reanalysis data.The results showed that in a typical La Niña event,after the peak has been reached,slow decay will occur during the first half of year+1.Then,the La Niña will re-develop into another La Niña during the following winter.In contrast,the special 1988 to 1989 La Niña event was observed to undergo a fast decay after its peak,and it then recovered to a climatological mean state by the end of the second year.The heat budget analysis results indicated that an anomalous zonal advection term related to wind force had contributed to the distinctive differences in the decaying rates between the typical and special 1988 to 1989 La Niña.During the decaying period,there was an anomalous anticyclone over the western North Pacific Ocean in the typical La Niña.In contrast,an anomalous cyclone event had occurred during the special 1988 to 1989 La Niña.The anomalous easterly winds south of an anticyclone can trigger upwelling Kelvin waves which propagate eastward,which maintain the cold SSTA in the equatorial eastern Pacific Ocean during a typical La Niña event.However,the anomalous westerly winds south of a cyclone can induce downwelling Kelvin waves propagating eastward,which caused the special 1988 to 1989 La Niña event to decay faster and then recover to a mean state by the end of the following year.
作者
陈明诚
黄玉蓉
CHEN Mingcheng;HUANG Yurong(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disaster(CIC-FEMD)/School of Atmospheric Sciences,Nanjing University of Information Science & Technology,Nanjing 210044,China)
出处
《大气科学学报》
CSCD
北大核心
2021年第3期428-440,共13页
Transactions of Atmospheric Sciences
基金
国家重点研发计划项目(2019YFC1510004)
江苏省自然科学基金青年基金项目(BK20180811)。
