Sea Surface Topography and Mass Transport of the Antarctic Circumpolar Current

该研究旨在确定绝对但随时间变化的海洋环流流场以及相关的质量和热量传输。它基于最先进的环流模型，吸收了动态海面地形（SST）的大地测量数据和海洋现场数据。 海洋模型主要关注南极绕极流的大西洋部分和威德尔海。由于环极地底水生产对全球深海环流的影响，这里是最具活力的海洋区域之一，也是全球气候最关键的区域之一。将高分辨率区域模型嵌入到较粗糙的全局模型中以避免系统失真。 大地测量海表温度（海平面和等位面之间最多 2 m 的小偏差）是根据 GRACE 和后来的 GOCE 卫星任务的新大地水准面模型，结合多任务卫星测高的海面高度的长期时间序列，以几厘米的精度确定的。这些卫星数据的精确度首次使所提出的方法得以实际实施。大地测量的重点是海表温度的最大空间分辨率和精度，包括彻底的误差估计、严格的误差传播和适应海洋模型有限元网格。动态一致海洋模型同化基于组合的大地测量-海洋学成本函数。迭代比较模型输入和输出，以评估每个数据集的一致性和海洋模型的参数化。

The study aims at the determination of the absolute, but temporally changing ocean circulation flow field and of associated mass and heat transports. It is based on a state-of-the-art circulation model assimilating geodetic data of the dynamic sea surface topography (SST) and oceanographic in-situ data. The ocean model is focused on the Atlantic sector of the Antarctic Circumpolar Current and the Weddell Sea. This is one of the most dynamic ocean areas and one of the most critical regions for global climate, due to the impact of circumpolar bottom water production on global deep sea circulation. The high resolution regional model is embedded into a coarser global model to avoid systematic distortions. The geodetic SST, a small up to 2 m deviation between sea level and equipotential surface, is determined with an accuracy of a few cm from the new geoid models from the GRACE and later GOCE satellite missions combined with a long-term time series of sea surface height from multi-mission satellite altimetry. The accuracy level of these satellite data enables for the first time the practical implementation of the proposed approach. The geodetic focus is on a maximum spatial resolution and accuracy in SST, including thorough error estimation, rigorous error propagation and adaptation to the ocean model finite element grid. The dynamically consistent ocean model assimilation is based on a combined geodetic-oceanographic cost function. The model input and output are iteratively compared to assess the consistency of each of the data sets and the parameterization of the ocean model.