Contributions of atmospheric and oceanic feedbacks to subtropical northeastern sea surface temperature variability
Contributions of atmospheric and oceanic feedbacks to subtropical northeastern sea surface temperature variability
复制标题
大气和海洋反馈对副热带东北海面温度变化的贡献
DOI：
10.1007/s00382-019-04964-1
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发表时间：
2019
期刊：
影响因子：
4.6
通讯作者：
Medeiros, Brian
中科院分区：
文献类型：
--
作者：
Middlemas, Eleanor;Clement, Amy;Medeiros, Brian
以往的研究表明，东北副热带太平洋和大西洋的主要变率模式是类似的。大部分的注意力都集中在风-蒸发-海面温度（WES）反馈上，但最近的研究表明云和海洋也起着作用。本文表明，虽然变率的模态相似，但云和海洋的定量作用是不同的。利用1.2版社区地球系统模型（Community Earth System Model），分别禁用云反馈和相互作用的海洋动力学，诊断两者对副热带东北洋盆海温（SST）变率的相对贡献。四个实验的结果表明，WES和云辐射反馈的相对贡献取决于海洋的作用。正云辐射反馈在两个盆地都很明显，但对大西洋海温变化的影响小于太平洋海温变化。这是因为海洋过程强烈地抑制了太平洋海温异常，而微弱地增强了大西洋海温异常。当云反馈失效时，海洋过程成为大西洋海温变率的更大驱动因素。根据以往的研究，东北太平洋海温的变率可以理解为一个白噪声强迫的线性随机系统，其正反馈来自云，并受到潜热通量和海洋过程的阻尼，而大西洋海温则部分受海洋环流变化的驱动，需要垂直混合才能再现。在这两个区域之间，不同的海洋动力导致不同的大气反馈作用，但仍然导致相似的海温变率模式。
Previous studies show that the dominant mode of variability in the Northeastern subtropical Pacific and Atlantic are analogous. Most attention has been given to the wind-evaporation-sea surface temperature (WES) feedback, but more recent studies suggest that clouds and ocean play a role. Here, it is shown that, while the mode of variability is similar, the quantitative role of clouds and ocean are different. Using Community Earth System Model, version 1.2, cloud feedbacks and interactive ocean dynamics are disabled separately to diagnose the relative contributions of each to sea surface temperature (SST) variability in subtropical northeastern ocean basins. Results from four experiments show that the relative contributions from WES and cloud radiative feedback depend on the role of the ocean. Positive cloud radiative feedback is evident in both basins but has less impact on SST variance in the Atlantic than in the Pacific. The reason for this is that ocean processes strongly damp SST anomalies in the Pacific and weakly enhance SST anomalies in the Atlantic. When cloud feedbacks are disabled, ocean processes become a larger driver of SST variability in the Atlantic. In line with previous studies, the Northeast Pacific SST variability may be understood as a white-noise-forced linear stochastic system with positive feedback from cloud and damping by latent heat flux and ocean processes, while Atlantic SST is driven partially by variations in ocean circulation and requires vertical mixing for rendition. Between these two regions, different ocean dynamics lead to different roles for atmospheric feedbacks but still result in similar patterns of SST variability.
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