Transport matrices from standard ocean-model output and quantifying circulation response to climate change
Transport matrices from standard ocean-model output and quantifying circulation response to climate change
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DOI：
10.1016/j.ocemod.2019.01.005
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发表时间：
2019-03-01
期刊：
影响因子：
3.2
通讯作者：
Marsland, Simon J.
中科院分区：
文献类型：
--
作者：
Chamberlain, Matthew A.;Matear, Richard J.;Marsland, Simon J.
提出了一种利用标准海洋模型输出（如平均体积通量和混合层深度）构造输运矩阵的方法。这些传输矩阵能够高效地计算深水示踪场，否则需要与正演时间步进海洋模型进行长时间的集成。理想平均水龄的矩阵解的比较表明，输运矩阵是母体海洋模式中输运的相当准确的表示。使用传输矩阵计算的示踪剂场提供了可以与观测值进行比较的简单循环指标。我们将两个版本的ACCESS海洋模型的矩阵计算放射性碳分布与观测结果进行了比较。我们发现基于这两种模型的矩阵产生现实的循环；基于CORE气候学强迫ACCESS模式的放射性碳分布较好地拟合了太平洋深处的观测数据，而完全耦合的ACCESS1.3模式较好地拟合了大西洋深处的观测数据。当应用于ACCESS1.3气候变化实验的环流时，运输矩阵解显示，在RCP8.5情景下，2090年代预估海洋环流中的放射性碳损耗或水龄增加。通过计算最后从特定区域通风的水质量分数，我们诊断出南极底水地层相应的渐进式关闭。南极水域在全球海洋中体积的减少被亚南极和南副热带最后一次通气的水域的增加所补偿。
A method to construct transport matrices from standard ocean-model output, such as mean volume fluxes and mixed-layer depths, is presented. These transport matrices enable highly efficient calculation of deep-water tracer fields that otherwise require long integrations with forward time-stepping ocean models. Comparisons of matrix solutions for ideal mean water age demonstrate that the transport matrices are reasonably accurate representations of the transport in the parent ocean models.Tracer fields calculated using transport matrices provide simple circulation metrics that can be compared to observations. We compare matrix-computed radiocarbon distributions from two versions of ACCESS ocean models with observations. We find matrices based on both models produce realistic circulations; the radiocarbon distribution based on ACCESS forced with CORE climatology fits observations better in the deep Pacific, whereas the fully coupled ACCESS1.3 model fits observations better in the deep Atlantic.When applied to the circulations of ACCESS1.3 climate-change experiments, the transport-matrix solutions show an increase in radiocarbon depletion, or water age, in the projected ocean circulation for the 2090s under the RCP8.5 scenario. By computing the water-mass fractions last ventilated from specific regions, we diagnose a corresponding progressive shutdown in Antarctic Bottom Water formation. The volumetric decrease in Antarctic waters in the global ocean is compensated by an increase in waters last ventilated in the subantarctic and southern subtropics.