Evaluation of the GECCO2 ocean synthesis: transports of volume, heat and freshwater in the Atlantic
Evaluation of the GECCO2 ocean synthesis: transports of volume, heat and freshwater in the Atlantic
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DOI：
10.1002/qj.2347
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发表时间：
2015-01-01
影响因子：
8.9
通讯作者：
Koehl, Armin
中科院分区：
文献类型：
--
作者：
Koehl, Armin
我们目前的结果，从一个新的合成（GECCO 2），其中涵盖了1948年至2011年采用类似的配置马萨诸塞州理工学院的一般循环模型作为前50年（1952年至2001年）GECCO合成。在GECCO 2中，分辨率有所提高;它现在包括北冰洋和一个动态/热力学海冰模型。合成使用伴随方法，使模型与现有的水文和卫星数据以及事先估计的表面通量的一致性。与GECCO相比，GECCO 2提供了与同化数据更好的一致性，但估计的通量调整仍然与GECCO相似。全球热含量的变化与最近的观测估计是一致的，全球热通量的估计接近辐射强迫的估计。两者都显示了火山爆发的辐射强迫的明显影响，与ENSO事件的关系较弱。在GECCO相反，大西洋经向翻转环流（AMOC）的变化的丹麦海峡溢出的重要性被取代在GECCO 2的副极地环流，这是示出的温盐环流的一部分，如果翻转被定义为密度的函数中的水团变换。在大西洋的热量和淡水运输的估计是更符合以前的估计比无约束运行。分解成翻转和环流组件的热量和淡水运输平均密度坐标表明，在这些坐标的贡献从环流环流基本上消失的热量运输和减少的淡水运输。
We present results from a new synthesis (GECCO2) which covers the years 1948 to 2011 employing a similar configuration of the Massachusetts Institute of Technology general circulation model as the previous 50-year (1952 to 2001) GECCO synthesis. In GECCO2, the resolution was increased; it now includes the Arctic Ocean and a dynamic/thermodynamic sea ice model. The synthesis uses the adjoint method to bring the model into consistency with available hydrographic and satellite data as well as prior estimates of surface fluxes. In comparison to GECCO, GECCO2 provides a better agreement with the assimilated data, however the estimated flux adjustments remain similar to GECCO. Global heat content changes are in agreement with recent observational estimates and the estimate of the global heat flux is close to a radiative forcing estimate. Both show a clear effect of the radiative forcing from volcanic eruptions and a weak relation to ENSO events. In contrast to GECCO, the importance of the Denmark Strait overflow for the variability of the Atlantic Meridional Overturning Circulation (AMOC) is replaced in GECCO2 by water mass transformation in the subpolar gyre, which is shown to be part of the thermohaline circulation if the overturning is defined as a function of density. Heat and freshwater transport estimates in the Atlantic are more consistent with previous estimates than the unconstrained run. Decomposing heat and freshwater transports into overturning and gyre components by averaging on density coordinates demonstrates that in these coordinates the contribution from the gyre circulation largely disappears for heat transport and is reduced for the freshwater transport.