Circulation-driven variability of Atlantic anthropogenic carbon transports and uptake
Circulation-driven variability of Atlantic anthropogenic carbon transports and uptake
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DOI：
10.1038/s41561-021-00774-5
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发表时间：
2021-07-08
影响因子：
18.3
通讯作者：
Messias, Marie-Jose
中科院分区：
文献类型：
--
作者：
Brown, Peter J.;McDonagh, Elaine L.;Messias, Marie-Jose
海洋吸收了目前人类活动释放到大气中的大约四分之一的二氧化碳(C-Anth)。由于大西洋子午线翻转环流(AMOC)和海-气交换输送的综合影响，北大西洋积累了不成比例的大部分。然而，由于海洋运输的变异性尚未解决，对海-气交换的模型估计和观测估计之间存在差异。在这里，我们利用快速系泊阵列的环流测量和水文观测，量化了2004至2012年间北大西洋26.5度C-Anth输送的强度和变异性。在此期间，环流强度的减弱往往会减少向北的C-Anth输送，而增加C-Anth的浓度(优先在翻转环流的上肢)则会增加向北的C-Anth输送。这两个过程在8.5年的时间里相互补偿。虽然海洋输送和海-气C-Anth通量在量级上大致相等，但北大西洋C-Anth的积累速度不断增加，加上稳定的海洋输送供应，我们推断在这段时间内，气-海C-Anth通量的贡献越来越大。北大西洋C-Anth累积对AMOC强度很敏感，但大气中不断增长的C-Anth吸收继续显著影响C-Anth输送。根据对海洋系泊环流观测的分析，2004年至2012年大西洋经向翻转环流的减弱导致其对北大西洋碳累积的相对贡献减少，而来自海-气通量的供应增加。
The ocean absorbs approximately a quarter of the carbon dioxide currently released to the atmosphere by human activities (C-anth). A disproportionately large fraction accumulates in the North Atlantic due to the combined effects of transport by the Atlantic Meridional Overturning Circulation (AMOC) and air-sea exchange. However, discrepancies exist between modelled and observed estimates of the air-sea exchange due to unresolved ocean transport variability. Here we quantify the strength and variability of C-anth transports across 26.5 degrees N in the North Atlantic between 2004 and 2012 using circulation measurements from the RAPID mooring array and hydrographic observations. Over this period, decreasing circulation strength tended to decrease northward C-anth transport, while increasing C-anth concentrations (preferentially in the upper limb of the overturning circulation) tended to increase northward C-anth transport. These two processes compensated each other over the 8.5-year period. While ocean transport and air-sea C-anth fluxes are approximately equal in magnitude, the increasing accumulation rate of C-anth in the North Atlantic combined with a stable ocean transport supply means we infer a growing contribution from air-sea C-anth fluxes over the period. North Atlantic C-anth accumulation is thus sensitive to AMOC strength, but growing atmospheric C-anth uptake continues to significantly impact C-anth transports.Slowdown of the Atlantic Meridional Overturning Circulation from 2004 to 2012 led to a decrease in its relative contribution to North Atlantic carbon accumulation, while the supply from air-sea fluxes increased, according to an analysis of ocean mooring circulation observations.