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| ENSO事件次表层海温的两个模态及其对大气环流的影响 |
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陈永利1,2,3, 唐晓晖1,2,3, 王凡1,2,3,4, 赵永平1,2
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1.中国科学院海洋研究所 海洋环流与波动重点实验室 青岛 266071;2.中国科学院海洋大科学研究中心 青岛 266071;3.青岛海洋科学与技术试点国家实验室 青岛 266237;4.中国科学院大学海洋学院 青岛 266071
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| 摘要: |
| 利用SODA海洋同化资料和NCEP再分析大气资料，分析了热带太平洋次表层海温异常（subsurface ocean temperature anomaly，SOTA）与厄尔尼诺与南方涛动（El Niño-Southern Oscillation，ENSO）循环的联系，及SOTA对大气环流的影响。回顾传统ENSO研究，指出存在的问题，提出了ENSO影响大气研究的新思路，得到以下结果：（1）以SOTA为基本资料的研究发现，ENSO事件有两个模态，主要出现在冬季的第一模态对冬季及夏季亚洲-北太平洋-北美地区上空中高纬大气环流有重要影响，主要出现在夏季的第二模态对该地区上空夏季热带和副热带大气系统有重要作用。（2）ENSO事件通过与ENSO相联系的热带太平洋海面温度异常（ENSO-related sea surface temperature anomaly，RSSTA）对大气的异常热通量输送，强迫Walker环流和Hadley环流变化，导致热带和北太平洋及周边地区上空大气环流异常，进而影响相关地区冬季和夏季的气候。（3）海表面温度异常（sea surface temperature anomaly，SSTA）包含RSSTA和大气异常导致的海温变化（sea temperature anomaly caused by atmospheric anomaly，STA）两部分，RSSTA是ENSO事件过程中海洋内部热动力结构调整导致的海面温度变化，在海洋对大气的热输送过程中，它随ENSO事件演变不断更新；STA是大气受RSSTA海洋异常加热后导致的大气环流异常对海面温度的影响，在海洋浅表层STA对RSSTA有重大影响。本文最后讨论了ENSO事件期间热带海洋对大气热输送过程，指出ENSO事件通过海洋内部热动力结构调整产生RSSTA，它直接对大气异常加热，导致大气环流和气候异常，局地海气之间负反馈过程产生STA，反过来抑制RSSTA。结果还指出，人们常用的SSTA变率实际上主要由秋冬季节RSSTA主导，丢失了春夏季ENSO信息，用SSTA研究ENSO事件存在局限性，这也可能是ENSO事件春季预报障碍的原因之一。 |
| 关键词: ENSO事件两个模态 海表面温度异常(sea surface temperature anomaly,SSTA) 次表层海温异常(subsurface ocean temperature anomaly,SOTA) 大气环流异常 海气热通量边界过程 |
| DOI：10.11693/hyhz20200100028 |
| 分类号:P731.27 |
| 基金项目:全球变化与海气相互作用专项，GASI-IPOVAI-01-01号；中国科学院战略性先导科技专项（B）类，XDB42000000号；国家自然科学基金重点项目，41730534号；国家自然科学研究基金创新群体科学基金，41421005号；国家自然科学基金委员会与山东省联合基金，U1406401号。 |
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| TWO MODES OF SUBSURFACE OCEAN TEMPERATURE ASSOCIATED WITH ENSO AND THEIR IMPACTS ON ATMOSPHERIC CIRCULATION |
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CHEN Yong-Li1,2,3, TANG Xiao-Hui1,2,3, WANG Fan1,2,3,4, ZHAO Yong-Ping1,2
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1.CAS Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China;3.Pilot National Laboratory for Marine Science and Technology(Qingdao), Qingdao 266237, China;4.College of Marine Science, University of Chinese Academy of Sciences, Qingdao 266071, China
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| Abstract: |
| Based on SODA ocean assimilation data and NCEP reanalysis atmospheric data, we analyzed the relationship between the tropical Pacific subsurface ocean temperature anomaly (SOTA) and El Niño-Southern Oscillation (ENSO) cycle, as well as the impact of SOTA on atmospheric circulation. By reviewing the traditional ENSO research, we pointed out the existing problems and proposed a new solution to study the influence of ENSO on atmospheric circulation. We found that (1) ENSO events have two modes as seen from the SOTA field. The first mode presents mainly in boreal winter, and affects the mid-latitude atmospheric circulation over the Asia-North Pacific-North America in winter and summer. The second mode appears in summer and has an important impact on atmospheric circulation over the tropical and subtropical system. (2) Via the ocean-to-atmosphere heat transport induced by the ENSO-related tropical Pacific sea surface temperature anomalies (RSSTA), the ENSO events influence the Walker circulation and Hadley cell, leading to variations of atmospheric circulation over the tropical and north Pacific, and hence the climate of the surrounding areas in winter and summer. (3) SSTA consists of RSSTA and sea temperature anomaly caused by atmospheric anomaly (STA). RSSTA is the sea surface temperature variations caused by internal thermodynamic adjustment in the ocean. It changes continuously with the evolution of ENSO events. STA is caused by the atmospheric forcing, which responds to the RSSTA. In the shallow surface layer, the STA has a significant influence on RSSTA. Finally, we discussed the heat transport processes in ocean-atmosphere boundary layer during ENSO events. We indicated that ENSO events give rise to the RSSTA by thermodynamic adjustment in the interior ocean, and the RSSTA directly heats the atmosphere, resulting in anomalous atmospheric circulation and the STA through local air-sea feedback process, which in turn holds back the RSSTA. Moreover, the SSTA variations are dominated actually by the RSSTA in fall-winter, while ENSO information in spring-summer is missing as seen from SSTA variations. There would be deficiency if studying ENSO by SSTA alone, which could also be one of the causes of spring barrier problem in ENSO predictability. |
| Key words: two modes of the ENSO events sea surface temperature anomaly (SSTA) subsurface ocean temperature anomaly (SOTA) anomalous atmospheric circulation ocean-atmosphere heat transport |