The Atlantic meridional overturning circulation (AMOC) is one of the main drivers of climate variability at decadal and longer time scales. As there are no direct multi-decadal observations of this key circulation, the reconstruction of past AMOC variations is essential. This work presents a step forward in reconstructing the AMOC using climate models and time-varying surface nudging of salinity and temperature data, for which independent multi-decadal observed series are available. A number of nudging protocols are explored in a perfect model framework to best reproduce the AMOC variability accommodating to the characteristics of SST and SSS available products. As reference SST products with sufficient space and time coverage are available, we here choose to focus on the limitations associated to SSS products with the goal of providing protocols using independent salinity products. We consider a global gridded dataset and, additionally, a coarser SSS dataset restricted to the Atlantic and with a quite low spatial resolution (order of 10 degrees vs. 2 for the model grid). We show how, using the latter, we can improve the efficiency of the nudging on the AMOC reconstruction by adding a high-resolution annual cycle to the coarse resolution SSS product as well as a spatial downscaling to account for SSS gradient. The final protocol retained for the coarse SSS data is able to reconstruct a 100-year long AMOC period (average of 10.18 Sv and a standard deviation of 1.39 Sv), with a correlation of 0.76 to the target and a RMSE of 0.99 Sv. These values can be respectively compared to 0.85 and 0.75 Sv when using the global salinity surface observations. This work provides a first step towards understanding the limitations and prospects of historical AMOC reconstructions using different sea surface salinity datasets for the surface nudging.

在十年和更长的时间尺度上，大西洋子午翻转循环（AMOC）是气候变化的主要驱动力之一。由于没有关于这一关键环流的直接多年代观测结果，因此重建过去的AMOC变化至关重要。这项工作提出了使用气候模型以及盐度和温度数据随时间变化的裸露面重建AMOC的新进展，为此可提供独立的多年代际观测序列。在完美的模型框架中探索了许多轻推协议，以最佳地再现适应SST和SSS产品特性的AMOC变异性。作为参考SST产品，它们具有足够的空间和时间覆盖范围，我们在这里选择专注于与SSS产品相关的限制，以提供使用独立盐度产品的协议为目标。我们考虑了一个全局网格化数据集，此外，还考虑了一个仅限于大西洋且空间分辨率相当低的较粗糙的SSS数据集（模型网格为10度vs. 2）。我们展示了如何使用后者，通过为粗分辨率SSS产品增加高分辨率的年周期以及考虑SSS梯度的空间缩小来提高AMOC重建的效率。为粗略SSS数据保留的最终协议能够重建100年的AMOC周期（平均10.18 Sv和1.39 Sv的标准偏差），与目标的相关系数为0.76，RMSE为0.99 Sv。这些值可以分别与0比较。使用整体盐度表面观测值时，分别为85和0.75 Sv。这项工作为了解使用不同海表盐度数据集进行表层裸露的AMOC历史重建的局限性和前景提供了第一步。