任宏昌,左金清,李维京. 2017. 1998年和2016年北大西洋海温异常对中国夏季降水影响的数值模拟研究[J]. 气象学报, 75(6):877-893, doi:10.11676/qxxb2017.063
1998年和2016年北大西洋海温异常对中国夏季降水影响的数值模拟研究
Role of the North Atlantic SST anomalies in the 1998 and 2016 summer floods in China
投稿时间:2017-01-05  修订日期:2017-05-16
DOI:10.11676/qxxb2017.063
中文关键词:  夏季降水  海温强迫  数值模拟  中高纬度环流  西北太平洋异常反气旋
英文关键词:Summer rainfall  Sea surface temperature forcing  Numerical simulation  Mid-high latitude circulation  Northwest Pacific anomalous anticyclone
基金项目:国家重点基础研究发展计划973项目(2013CB430203)、公益性行业(气象)科研专项(GYHY201306033)、“十三五”国家重点研发计划项目(2016YFA0601501)。
作者单位E-mail
任宏昌 南京信息工程大学气象灾害预报预警与评估协同创新中心, 南京, 210044
中国气象局气候研究开放实验室, 北京, 100081
国家气象中心, 北京, 100081 
 
左金清 南京信息工程大学气象灾害预报预警与评估协同创新中心, 南京, 210044
中国气象局气候研究开放实验室, 北京, 100081 
jqzuo425@126.com 
李维京 南京信息工程大学气象灾害预报预警与评估协同创新中心, 南京, 210044
中国气象局气候研究开放实验室, 北京, 100081 
 
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中文摘要:
      基于1979-2016年ERA-Interim再分析资料和CAM5.3模式,研究了2016年和1998年北大西洋海温异常对中国夏季降水以及大尺度环流的可能影响及其机制。结果表明,这两年前夏(6-7月)长江中下游及其以南地区降水均异常偏多,但1998年降水异常较2016年更为显著。后夏(8月),2016年长江以南地区降水异常偏多,长江-黄河流域降水异常偏少,而1998年降水异常分布与之相反。2016年和1998年夏季中国东部降水异常的差异与西北太平洋对流层低层异常反气旋以及欧亚中高纬度环流变化的共同作用直接相关。敏感性数值试验的结果表明,北大西洋海温异常的显著差异是导致2016年和1998年夏季中国东部降水以及大尺度环流异常存在明显差异的重要原因之一。一方面,北大西洋海温异常可以通过改变欧亚中高纬度环流进而对中国夏季降水产生影响。1998年北大西洋海温异常自热带至副极地呈类似"+-+"型分布,这种海温异常型能够在前夏欧亚中高纬度地区激发出双阻型的环流异常响应。2016年北大西洋海温异常自热带至副极地呈相对弱的"-+-"型分布,欧亚中高纬度环流异常响应总体偏弱。另一方面,北大西洋海温异常还可以通过影响热带纬向环流进而对西北太平洋对流层低层异常反气旋起调制作用。1998年北大西洋海温异常对夏季西北太平洋异常反气旋起增强作用,这与热带印度洋-太平洋海温的强迫作用相协调。然而,2016年北大西洋海温异常则有利于西北太平洋异常反气旋的减弱,这与热带印度洋-太平洋海温的强迫作用相反。因此,在这3个大洋的协同作用下,2016年和1998年前夏西北太平洋异常反气旋均偏强,但前者的振幅弱于后者。在后夏,1998年西北太平洋对流层低层仍受异常反气旋控制,2016年则为异常气旋控制。
英文摘要:
      Based on the ERA-Interim reanalysis data from 1979 to 2016 and numerical modeling simulations (CAM5.3), the present study investigates impacts of the North Atlantic Sea surface temperature (SST) anomalies on China rainfall during the summer of 2016 and 1998 and the possible physical mechanisms during summer of 2016 and 1998 are investigated in the present study. It is suggested that the difference in the North Atlantic SST anomaly patterns between 2016 and 1998 makes important contribution to differences in eastern China summer rainfall and the associated circulation anomalies. The pattern of rainfall anomalies during the early summer (June-July) of 2016 was similar to that in 1998, except for more rainfall in the southern of Yangtze River valley in 1998. However, the patternss of rainfall anomalies during the late summer (August) were almost opposite in between these two years. The differences in summer rainfall anomalies between 2016 and 1998 were directly resulted from circulation anomalies in the Northwest Pacific and the Eurasian mid-high latitudes, which were both closely linked to the North Atlantic SST anomalies. On one hand, the North Atlantic SST anomalies could exert a downstream impact on the early summer rainfall of 1998 by inducing a Rossby wave-trains over the Eurasian mid-high latitudes, which was favorable for more rainfall in southern China. However, while the response of Eurasian circulation to the North Atlantic SST forcing was relatively weak in 2016. On the other hand, the North Atlantic SST anomalies could also exert an impact on the circulation over the Northwest Pacific through a westward propagating subtropical teleconnection. In both the early and late summer of 1998, the North Atlantic SST forcing was consistent with that of the tropical Indo-Pacific SST forcing, which resulted in a strong anomalous low-level anticyclone over the Northwest Pacific. However, the anomalous low-level anticyclone in early summer of 2016 was weaker than that in 1998 due to the opposite impacts of the SST anomalies in between the North Atlantic and the tropical Indo-Pacific Ocean. In contrast, an anomalous low-level cyclone was observed over the Northwest Pacific due to the dominant impact role of North Atlantic SST forcing in late summer of 2016.
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