全球变暖背景下赤道太平洋温跃层的快慢变化特征与机制  

Fast and Slow Responses of the Thermocline to Global Warming in the Tropical Pacific:Characteristics and Mechanisms

作　　者：解晗 郑小童 龙上敏 XIE Han;ZHENG Xiao-Tong;LONG Shang-Min(The Key Laboratory of Physical Oceanography,Ministry of Education,College of Oceanic and Atmospheric Sciences,Ocean University of China,Qingdao 266100,China;Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China;International Polar Environment Research Laboratory,College of Oceanography,Hehai University,Nanjing 210000,China)

机构地区：[1]中国海洋大学物理海洋教育部重点实验室,海洋与大气学院,山东青岛266100 [2]青岛海洋科学与技术试点国家实验室,山东青岛266237 [3]河海大学海洋学院国际极地环境研究实验室,江苏南京210000

出　　处：《中国海洋大学学报（自然科学版）》2021年第1期9-16,共8页Periodical of Ocean University of China

基　　金：国家重点研究发展计划项目(2018YFA0605704);国家自然科学基金项目(41975092)资助。

摘　　要：本文利用GFDL CM2.1模拟的1%CO2增长理想试验结果,分析了在全球变暖背景下赤道太平洋温跃层深度的快慢两个时间尺度的变化特征。研究表明:在CO2浓度快速增加的阶段,赤道太平洋上层海洋层结增强,温跃层深度快速变浅(该阶段称为“快速变化阶段”)且存在空间上的不均匀:在赤道中西太平洋(160°E~160°W之间)变浅最明显(约20 m),在赤道东太平洋(160°W向东)其变浅程度越来越小;在CO2浓度达到稳定的阶段,赤道太平洋温跃层深度呈现缓慢变化阶段。研究发现,温跃层快速变化的空间不均匀是因为在赤道中太平洋和东太平洋温跃层快速变化的机制不同:在赤道中太平洋背景东风加强,上层层结与上升流的都加强有利于抬升温跃层,而在赤道东太平洋背景东风减弱,导致上升流减弱不利于温跃层变浅;上升流变化的作用部分抵消了上层层结加强对温跃层变浅的作用,故温跃层变浅要小于160°W以西。在赤道以外海区(南北纬3°~7°),海洋层结减弱和垂直流速变化分别加深和抬升温跃层,导致此处温跃层变浅不明显。而在CO2浓度达到稳定后的140年,即温跃层缓慢变化阶段,海洋层结缓慢加强,温跃层变化幅度远小于快过程。Fast and slow responses of the equatorial Pacific thermocline to global warming are investigated based on a 1%a-1 CO2 increasing experiment of Geophysical Fluid Dynamics Laboratory version 2.1.The results show that upper-ocean stratification strengthens during the transient increase of CO2 concentration,leading to rapid shoaling of thermocline depth with an uneven spatial distribution in the equatorial Pacific.The thermocline shoaling is largest(~20 m)in the central and western Pacific(160°E~160°W)but insignificant in the eastern Pacific(east of 160°W).In contrast,thermocline depth changes little after CO2 concentration stabilizes.It is found that the uneven thermocline change in the fast response is due to the different mechanisms in the equatorial central Pacific and the eastern Pacific In the central equatorial Pacific,the upper-ocean stratification and upwelling both shoals the thermocline due to the strengthening of the easterly winds.In contrast,while the easterly winds weaken in the eastern equatorial Pacific,resulting in the weakening of upwelling that offsets the effect of stratification change.Thus,thermocline shoals little in the eastern Pacific.Outside the equatorial Pacific,the effect of stratification change also deepens the thermocline and offsets the effect of vertical velocity change.When CO2 concentration stabilizes after 140 years,the change in thermocline depth is far less than that in the fast response.

关 键 词：温跃层深度 全球变暖 热带太平洋 海洋层结 赤道上升流 

分 类 号：P731.24[天文地球—海洋科学]