用偏最小二乘(Partial Least Square,PLS)回归方法分析了1979~2018年影响亚马逊旱季(6~8月)降水年际变率的热带海面温度模态。第一海面温度模态解释了总方差的64%,主要表现为前期亚马逊雨季(12月至次年2月)至旱季(6~8月)热带东太平洋La ...用偏最小二乘(Partial Least Square,PLS)回归方法分析了1979~2018年影响亚马逊旱季(6~8月)降水年际变率的热带海面温度模态。第一海面温度模态解释了总方差的64%,主要表现为前期亚马逊雨季(12月至次年2月)至旱季(6~8月)热带东太平洋La Niña型海面温度异常演变。12月至次年2月热带东太平洋出现La Niña型海面温度冷异常;3~5月热带东太平洋冷异常增强,并在热带印度洋、热带北大西洋出现冷异常,在热带南大西洋有暖异常;6~8月热带东太平洋冷异常向东收缩;9~11月整个热带海面温度异常均快速衰退。第二海面温度模态解释了总方差的19%,主要表现为前期亚马逊雨季(12月至次年2月)至旱季(6~8月)中太平洋Modoki El Niño型增暖。12月至次年2月在热带中太平洋出现暖异常,印度洋和南大西洋同样也出现暖异常,热带中太平洋和南大西洋暖异常能持续到9~11月,而印度洋暖异常在9~11月衰减。这些结果表明,亚马逊旱季降水与热带海面温度的演变有关,当前期12月至次年2月出现La Niña(Modoki El Niño)事件、3~8月出现热带南北大西洋海面温度梯度负异常并且热带印度洋海面温度冷(暖)异常时,亚马逊旱季降水偏多。这两个海面温度模态对降水的总贡献与亚马逊旱季降水指数的相关关系高达0.92,说明亚马逊旱季降水年际变率与热带海面温度密切相关;而且这两个海面温度模态对亚马逊旱季降水的贡献还有明显的年代际变化,自1979年以来,海面温度对降水的贡献有下降趋势。还对海面温度影响亚马逊旱季降水年际变率的机制进行了分析,发现海面温度可以通过影响亚马逊地区的环流场、水汽输送以及大气对流层稳定性进而导致降水异常。第一海面温度模态能激发亚马逊低空北部气流辐合,高空北部气流辐散,容易形成异常的上升运动;同时,亚马逊对流层的异常湿静能收支也表明第一海面温�展开更多
An unusually warm East Asia in spring 2018,when exceptionally high surface air temperatures were recorded in large areas of Asia,such as northern China,southern China,and Japan,was investigated based on the ERA-Interi...An unusually warm East Asia in spring 2018,when exceptionally high surface air temperatures were recorded in large areas of Asia,such as northern China,southern China,and Japan,was investigated based on the ERA-Interim reanalysis.The East Asian warming anomalies were primarily attributed to a tripole mode of North Atlantic SST anomalies,which could have triggered anomalous Rossby wave trains over the North Atlantic and Eurasia through modulating the North Atlantic baroclinic instability.Atlantic-forced Rossby waves tend to propagate eastward and induce anomalously high pressure and anticyclonic activity over East Asia,leading to a northward displacement of the Pacific subtropical high.As a result,descending motion,reduced precipitation,and increased surface solar radiation due to less cloud cover appear over East Asia,accompanied by remarkably warm advection from the ocean to southern China,northern China,and Japan.The transportation of anomalously warm advection and the feedbacks between soil moisture and surface temperature were both favorable for the recordbreaking warmth in East Asia during spring 2018.The seasonal‘memory’of the North Atlantic tripole SST mode from the previous winter to the following spring may provide useful implications for the seasonal prediction of East Asian weather and climate.展开更多
文摘用偏最小二乘(Partial Least Square,PLS)回归方法分析了1979~2018年影响亚马逊旱季(6~8月)降水年际变率的热带海面温度模态。第一海面温度模态解释了总方差的64%,主要表现为前期亚马逊雨季(12月至次年2月)至旱季(6~8月)热带东太平洋La Niña型海面温度异常演变。12月至次年2月热带东太平洋出现La Niña型海面温度冷异常;3~5月热带东太平洋冷异常增强,并在热带印度洋、热带北大西洋出现冷异常,在热带南大西洋有暖异常;6~8月热带东太平洋冷异常向东收缩;9~11月整个热带海面温度异常均快速衰退。第二海面温度模态解释了总方差的19%,主要表现为前期亚马逊雨季(12月至次年2月)至旱季(6~8月)中太平洋Modoki El Niño型增暖。12月至次年2月在热带中太平洋出现暖异常,印度洋和南大西洋同样也出现暖异常,热带中太平洋和南大西洋暖异常能持续到9~11月,而印度洋暖异常在9~11月衰减。这些结果表明,亚马逊旱季降水与热带海面温度的演变有关,当前期12月至次年2月出现La Niña(Modoki El Niño)事件、3~8月出现热带南北大西洋海面温度梯度负异常并且热带印度洋海面温度冷(暖)异常时,亚马逊旱季降水偏多。这两个海面温度模态对降水的总贡献与亚马逊旱季降水指数的相关关系高达0.92,说明亚马逊旱季降水年际变率与热带海面温度密切相关;而且这两个海面温度模态对亚马逊旱季降水的贡献还有明显的年代际变化,自1979年以来,海面温度对降水的贡献有下降趋势。还对海面温度影响亚马逊旱季降水年际变率的机制进行了分析,发现海面温度可以通过影响亚马逊地区的环流场、水汽输送以及大气对流层稳定性进而导致降水异常。第一海面温度模态能激发亚马逊低空北部气流辐合,高空北部气流辐散,容易形成异常的上升运动;同时,亚马逊对流层的异常湿静能收支也表明第一海面温�
基金supported by the National Key Research and Development Program of China [grant number2016YFA0602703]the National Natural Science Foundation of China [grant numbers 41661144019,41690123,41690120,and91637208]+1 种基金the CMA Guangzhou Joint Research Center for Atmospheric Sciencesthe Jiangsu Collaborative Innovation Center for Climate Change
文摘An unusually warm East Asia in spring 2018,when exceptionally high surface air temperatures were recorded in large areas of Asia,such as northern China,southern China,and Japan,was investigated based on the ERA-Interim reanalysis.The East Asian warming anomalies were primarily attributed to a tripole mode of North Atlantic SST anomalies,which could have triggered anomalous Rossby wave trains over the North Atlantic and Eurasia through modulating the North Atlantic baroclinic instability.Atlantic-forced Rossby waves tend to propagate eastward and induce anomalously high pressure and anticyclonic activity over East Asia,leading to a northward displacement of the Pacific subtropical high.As a result,descending motion,reduced precipitation,and increased surface solar radiation due to less cloud cover appear over East Asia,accompanied by remarkably warm advection from the ocean to southern China,northern China,and Japan.The transportation of anomalously warm advection and the feedbacks between soil moisture and surface temperature were both favorable for the recordbreaking warmth in East Asia during spring 2018.The seasonal‘memory’of the North Atlantic tripole SST mode from the previous winter to the following spring may provide useful implications for the seasonal prediction of East Asian weather and climate.
