Trends in water mass properties in the Weddell Sea from assimilation of float data in a regional ocean model

气候变化在很大程度上受海洋关键区域变化的影响。威德尔海就是这样一个关键区域，在这里形成了大量的南极底水（AABW），对经向翻转环流（MOC）有重要贡献。到目前为止，水文观测在时间上强烈偏向夏季，在空间上偏向两个重复的woce剖面。在这个项目中，所有可用的观测数据将在动力一致性数据同化的帮助下与数值海洋模式相结合，形成威德尔海的完整状态估计。主要的重点放在收集和使用新开发的冰兼容Argo浮标的温度和盐度剖面，这消除了上述偏差。由此得出的估计和威德尔海的完整相空间轨迹将使我们能够回答以下问题：•威德尔环流中的水团性质是如何变化的，特别是在多大程度上是整个威德尔海的稀疏水文观测特征？•是什么导致威德尔海的水团性质发生变化？•水质量特性和环极深水（CDW）流入在多大程度上受短期和中期变化的影响？有可能发现长期趋势吗？•wdw范围的变化如何影响威德尔海的深水和底水形成？此外，这项工作将提供威德尔环流水团特性的动态一致的时间序列，并将对“南大洋大西洋部分在气候系统中的作用”项目包做出重要贡献。

Climate change is strongly conditioned by variations in key areas of the ocean. The Weddell Sea is such a key area, where a major amount of Antarctic Bottom Water (AABW) is formed as an essential contribution to the Meridional Overturning Circulation (MOC). Up to now, hydrographic observations were strongly biased in time toward summer season and spatially toward two repeated WOCE-sections. Within this project all available observational data will be combined with a numerical ocean model with the help of dynamical consistent data assimilation into a complete stateestimate of the Weddell Sea. The main emphasis is placed on collecting and using temperature- and salinity profiles of newly developed ice compatible Argo floats which remove the aforementioned biases. The resulting estimate and the complete phase-space trajectory of the Weddell Sea will enable us to answer the following questions: • How do water mass properties change in the Weddell Gyre, in particular to what extent are the sparse hydrographic observations characteristic for the entire Weddell Sea? • What causes the changes in water mass properties within the Weddell Sea? • To what extent are water mass properties and inflow of Circumpolar Deep Water (CDW) subject of short- and intermediate term variations? Is it possible to detect long-term trends? • How do variations in the WDW-range affect deep and bottom water formation within the Weddell Sea? Further, this work will provide a dynamically consistent time series of the water mass properties of the Weddell Gyre and will be an essential contribution to the project bundle “The role of the Atlantic sector of the Southern Ocean in the climate system”.