A new conceptual model of global ocean heat uptake
A new conceptual model of global ocean heat uptake
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DOI：
10.1007/s00382-023-06989-z
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发表时间：
2023-12
期刊：
影响因子：
4.6
通讯作者：
J. Gregory;J. Bloch‐Johnson;M. Couldrey;E. Exarchou;S. Griffies;T. Kuhlbrodt;E. Newsom;O. Saenko;Tatsuo Suzuki;Quran Wu;Shogo L. Urakawa;L. Zanna
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作者：
J. Gregory;J. Bloch‐Johnson;M. Couldrey;E. Exarchou;S. Griffies;T. Kuhlbrodt;E. Newsom;O. Saenko;Tatsuo Suzuki;Quran Wu;Shogo L. Urakawa;L. Zanna
我们制定了一个新的概念模型，命名为“MT2”，来描述全球海洋热量吸收，通过大气二氧化碳增加所迫使的大气-海洋环流模型（AOGCM）进行模拟，作为全球平均表面温度变化和大西洋经向翻转环流（AMOC，M）强度的函数。MT2有两条热量到达深海的途径。根据间接证据，我们假设将这些路线识别为低纬度和高纬度路线。在主导全球平均能量平衡的低纬度地区，吸热量是温度驱动的，并由两层模型描述，全球平均Ta是上层的温度变化。在高纬度地区，一部分强迫（约14%）沿等密度线吸收，主要在南大洋，几乎像被动示踪剂，与T无关。由于该比例与未扰动气候下的 AMOC 强度呈线性关系，因此我们假设高纬度吸热量和 AMOC 均受到未扰动全球海洋状态的某些特征的影响，可能与分层有关。MT2 可以解释 AOGCM 预测之间的几种关系，其中一些在本工作中发现，另一些之前报道过：海洋吸热效率与 AMOC 密切相关。全球海洋吸热与 AMOC 不相关。瞬态气候响应(TCR) 与 AMOC 反相关。在高强迫情景下预测的 21 世纪末 T 与有效气候敏感性的相关性比与 TCR 的相关性更强。
We formulate a new conceptual model, named “MT2”, to describe global ocean heat uptake, as simulated by atmosphere–ocean general circulation models (AOGCMs) forced by increasing atmospheric CO, as a function of global-mean surface temperature changeTand the strength of the Atlantic meridional overturning circulation (AMOC,M).MT2 has two routes whereby heat reaches the deep ocean. On the basis of circumstantial evidence, we hypothetically identify these routes as low- and high-latitude. In low latitudes, which dominate the global-mean energy balance, heat uptake is temperature-driven and described by the two-layer model, with global-meanTas the temperature change of the upper layer. In high latitudes, a proportionp(about 14%) of the forcing is taken up along isopycnals, mostly in the Southern Ocean, nearly like a passive tracer, and unrelated toT. Because the proportionpdepends linearly on the AMOC strength in the unperturbed climate, we hypothesise that high-latitude heat uptake and the AMOC are both affected by some characteristic of the unperturbed global ocean state, possibly related to stratification.MT2 can explain several relationships among AOGCM projections, some found in this work, others previously reported:Ocean heat uptake efficiency correlates strongly with the AMOC.Global ocean heat uptake is not correlated with the AMOC.Transient climate response (TCR) is anticorrelated with the AMOC.Tprojected for the late twenty-first century under high-forcing scenarios correlates more strongly with the effective climate sensitivity than with the TCR.