Collaborative Research: The Role of Ocean Dynamical Feedback and Air-Sea Interaction in the Climate Response to Global Warming

合作研究：海洋动力反馈和海气相互作用在全球变暖气候响应中的作用

• 批准号: 1249145
• 负责人: Shang-Ping Xie
• 金额: $ 33.21万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1249145&HistoricalAwards=false
• 关键词: Collaborative; Research; Role; Ocean; Dynamical

This project considers changes in regional climate occurring primarily in and over the tropical oceans, due to greenhouse gas increases. Among the robust regional climate changes found in ensembles of climate model simulations, three are addressed here: a pattern of "El Nino-like" sea surface temperature (SST) changes in the tropical Pacific; a minimum in the warming of SSTs in the tropical North Atlantic area which is the main development region (MDR) for Atlantic tropical cyclones, accompanied by an increase in vertical wind shear in the region (which would presumably inhibit tropical cyclone formation); and the meridional shift in the intertropical convergence zone (ICTZ) which has been tentatively ascribed to the slowdown of the Atlantic meridional overturning circulation (AMOC) caused by global warming. These regional changes will be examined by decomposing local SST change into components forced separately by 1) the increase in local surface radiation; 2) redistribution of changes in near-surface heat ocean content by the mean ocean circulation; 3) redistribution of the mean near-surface heat content by changes in the wind-driven surface currents; and 4) changes in evaporative cooling due to changes in surface wind speed. The four terms, which come from a linearization of the perturbation surface energy balance equation, have been previously associated with specific mechanisms of regional SST change. In particular term 4 expresses the dynamics of the wind-evaporation-SST (WES) feedback, in which the quadratic dependence of evaporation on surface wind speed cause evaporative cooling to vary regionally according to the strength of the mean winds and their direction relative to changes in wind. Likewise term 2 encapsulates the ocean dynamical thermostat (ODT) mechanism, in which a uniform increase in surface energy input causes less local SST increase in a region of divergent surface currents as the additional heat is transported out of the region. This mechanism would be expected to yield a reduction in SST warming in the Eastern Pacific cold tongue region relative to the western Pacific, thereby acting to oppose the El Nino-like warming pattern found in climate change simulations. The methodology for determining the relative contributions of the terms involves numerical integrations of a climate model in configurations in which the terms are selectively enabled and disabled. Beyond its intrinsic scientific value, the work has broader impacts due to the consequences of changes in tropical ocean conditions have for fisheries, marine ecology, and the formation of tropical cyclones. The work will also help to determine the extent to which climate model simulations can be confidently used to anticipate climate change at regional scales.

该项目考虑了由于温室气体增加而主要发生在热带海洋及其上空的区域气候变化。在气候模型模拟集合中发现的剧烈区域气候变化中，这里讨论了三个：热带太平洋“类厄尔尼诺”海面温度（SST）变化的模式；北大西洋热带地区海温变暖达到最低值，该地区是大西洋热带气旋的主要发展区域（MDR），同时该地区垂直风切变增加（这可能会抑制热带气旋的形成）；热带辐合带（ICTZ）的经向移动暂时归因于全球变暖引起的大西洋经向翻转环流（AMOC）的减慢。这些区域变化将通过将局部海温变化分解为分别受以下因素影响的分量来检查：1）局部表面辐射的增加； 2）平均海洋环流对近地表热海洋含量变化的重新分配； 3）通过风驱动的表面流的变化来重新分布平均近地表热含量； 4）由于表面风速的变化而导致的蒸发冷却的变化。这四项来自扰动表面能量平衡方程的线性化，之前已与区域海温变化的具体机制相关联。特别是，第 4 项表示风-蒸发-海温（WES）反馈的动态，其中蒸发对表面风速的二次依赖性导致蒸发冷却根据平均风的强度及其相对变化的方向而局部变化。在风中。同样，第 2 项封装了海洋动力恒温器 (ODT) 机制，其中表面能量输入的均匀增加导致表面流发散区域中局部海温增加较少，因为额外的热量被传输出该区域。预计这一机制将减少东太平洋冷舌地区相对于西太平洋的海温变暖，从而对抗气候变化模拟中发现的类似厄尔尼诺的变暖模式。用于确定这些项的相对贡献的方法涉及气候模型在选择性启用和禁用这些项的配置中的数值积分。除了其内在的科学价值之外，由于热带海洋条件的变化对渔业、海洋生态和热带气旋形成的影响，这项工作还具有更广泛的影响。这项工作还将有助于确定气候模型模拟在多大程度上可以自信地用于预测区域尺度的气候变化。