Local and Remote Influences on the Heat Content of Southern Ocean Mode Water Formation Regions
Local and Remote Influences on the Heat Content of Southern Ocean Mode Water Formation Regions
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DOI：
10.1029/2020jc016585
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发表时间：
2021-04-01
影响因子：
3.6
通讯作者：
Josey, Simon A.
中科院分区：
文献类型：
--
作者：
Boland, Emma J. D.;Jones, Daniel C.;Josey, Simon A.
南大洋是全球海洋吸收热量和碳的关键区域。大气与海洋混合层之间热量和碳通量的观测存在很大的不确定性，这导致进入全球翻转环流的量也存在很大的不确定性。为了更好地了解热量和动量通量在何时何地对近表层热量含量影响最大，我们使用一个伴随模型来计算南大洋模态水形成区域热量含量对表面通量的线性敏感度。我们发现，在所有三个海盆中，这些区域的热量含量对同冬季的本地热量通量以及1到8年前（我们模拟的最大提前时间）的本地和远程风最为敏感。对位温变化的敏感度也支持了这一点，它揭示了模态水形成区域的来源以及与边界流区域和南极绕极流的动态联系。我们利用伴随敏感度场设计了一组有针对性的扰动实验，使我们能够研究热量含量对表面强迫变化的线性和非线性响应。在这些有针对性的实验中，热量含量对温度变化和混合层体积变化的敏感度大致相同。
The Southern Ocean (SO) is a crucial region for the global ocean uptake of heat and carbon. There are large uncertainties in the observations of fluxes of heat and carbon between the atmosphere and the ocean mixed layer, which lead to large uncertainties in the amount entering into the global overturning circulation. In order to better understand where and when fluxes of heat and momentum have the largest impact on near-surface heat content, we use an adjoint model to calculate the linear sensitivities of heat content in SO mode water formation regions (MWFRs) to surface fluxes. We find that the heat content of these regions is, in all three basins, most sensitive to same-winter, local heat fluxes, and to local and remote wind one to eight years (the maximum lead-time of our simulations) previously. This is supported by sensitivities to potential temperature changes, which reveal the sources of the MWFRs as well as dynamic links with boundary current regions and the Antarctic Circumpolar Current. We use the adjoint sensitivity fields to design a set of targeted perturbation experiments, allowing us to examine the linear and non-linear responses of the heat content to changes in surface forcing. In these targeted experiments, the heat content is sensitive to both temperature changes and mixed layer volume changes in roughly equal magnitude.