秋季北极海冰对EP ENSO的非线性响应
投稿时间: 2017-10-26  最后修改时间: 2017-12-06  点此下载全文
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作者单位E-mail
祁莉 南京信息工程大学大气科学学院 qili@nuist.edu.cn 
马威威 南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心  
何金海 南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心  
耿新 南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心  
基金项目:国家自然科学基金资助项目(41475086);长江学者和创新团队发展计划资助(PCSIRT);江苏高校优势学科建设工程资助项目(PAPD)
中文摘要:利用1961-2015年Hadley中心逐月海表温度资料、海冰密集度资料以及NCEP/NCAR再分析资料,探讨了秋季北极海冰对于EP型ENSO事件的异常响应,并进一步研究了这种异常响应的可能原因。结果表明,秋季北极海冰对EP型ENSO的响应具有非线性。特别是喀拉海海域(60-90癊,70-80癗)海冰无论在EP型El Ni駉或是La Ni馻位相,均表现为显著的负异常。进一步研究发现,不同ENSO位相造成该地区海冰异常偏少的机制却明显不同。EP El Ni駉年秋季菲律宾附近海域对流活动被抑制,所激发的经向波列在高纬地区形成异常反气旋环流,其南风分量向喀拉海输送暖平流,造成海冰异常偏少。而EP La Ni馻年喀拉海海域则主要受到来自大西洋开放性海域西风异常的影响,合成结果和个例年均显示EP型La Ni馻年秋季北大西洋上空存在一个显著的西风急流中心,有利于北大西洋开放性海域较暖海水向下游输送,进而影响喀拉海海冰。这些结果表明,热带外地区的大气环流场对于EP ENSO的非线性响应,导致了喀拉海海冰对EP型ENSO事件的响应也表现出明显的非线性。
中文关键词:EP ENSO,北极海冰,非线性响应,波列,西风急流
 
Nonlinear Response of Arctic Sea Ice to EP ENSO in Autumn
Abstract:Based on the monthly Hadley Center sea surface temperature data, Hadley Center Arctic sea ice concentration data, and the National Centers for Environmental Prediction (NCEP)/the National Center for Atmospheric Research (NCAR) reanalysis data during the period of 1961-2015, we analyzed the abnormal response of Arctic sea ice to EP ENSO event in autumn, and the possible causes of such a abnormal response are furtherly discussed. Results show that the response of Arctic sea ice to EP ENSO in autumn is nonlinear. Particularly, sea ice concentration anomalies in the Kara Sea area(60-90癊,70-80癗) are significantly negative both in the EP El Ni駉 and EP La Ni馻 phases. Further analyses reveal that the mechanism of sea ice anomalies in different EP ENSO phases is significantly different. For EP El Ni駉, the suppression of the convective activity in the waters near the Philippines stimulates the meridian wave train in the extratropical area. Meanwhile, the southward wind component of the anti-cyclonic circulation responsed to the wave train in the high latitudes, forms warm convection transport to the Kara Sea area and causes sea ice retreat as a result. However, the same sea area is mainly influenced by the westerly anomalies from the Atlantic open sea during EP La Ni馻. Moreover, both of the composite results and individual EP La Ni馻 events show that there is a upper level westerly jet center over the North Atlantic Ocean in the autumn, which is conducive to the open water of the North Atlantic Ocean downstream transport, affecting the Kara Sea area as a result. The above results show that, the nonlinear response of the circulation field in the extratropical area to EP ENSO, leads to a significant nonlinear response of Arctic sea ice to EP ENSO in turn.
keywords:Eastern Pacific ENSO,Arctic sea ice,Nonlinear response,Wave train,Upper level westerly jet
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