World ocean annual mean absolute geostrophic velocity on marine geoid of EIGEN-6C4 from WOA13 (NCEI Accession 0208329)

This dataset contains annual mean geostrophic velocity calculated at depth corresponding to negative values of the marine geoid. It is calculated from two open sources from the geodetic (EIGEN-6C4) and oceanographic (NCEI) communities. The first source EIGEN-6C4 is a static global combined gravity field model developed by GFZ Potsdam and GRGS Toulouse up to degree and order 2190. The second source is the “World ocean geostrophic velocity inverted from World Ocean Atlas 2013 with the P-vector method” (NCEI accession 0121576). With the given non-positive values of the geoid, N, (i.e., for the oceans), the absolute geostrophic currents (u, v) are easily identified on N with 1 degree resolution from the second dataset except the equatorial zone (5oS – 5oN) due to the non-existence of the geostrophic balance. Altogether, the dataset contains 15,481 (u, v) data pairs. While there is no geostrophic motion at the surface if it coincided with the geoid, the opposite is not valid. This dataset shows that ocean geostrophic velocity doesn't zero at z=N. Data are in netcdf format.

本数据集包含在对应海洋大地水准面为负值的深度处计算得到的年平均地转流速，其基于大地测量与海洋学领域的两个公开数据源计算所得。首个数据源为EIGEN-6C4，这是由波茨坦德国地学研究中心（GFZ Potsdam）与图卢兹大地测量与地球动力学研究组（GRGS Toulouse）开发的静态全球组合重力场模型，球谐展开阶次与次数最高可达2190。第二个数据源为"基于P矢量法从2013年世界海洋图集反演得到的全球海洋地转流速数据集"，其美国国家环境信息中心（NCEI）存档编号为0121576。针对大地水准面N取非正值的海洋区域，除赤道带（南纬5°至北纬5°）因不存在地转平衡无法开展计算外，可从第二份数据集中以1度分辨率提取绝对地转流（u, v）。本数据集总计包含15481组(u, v)数据对。若海洋表面与大地水准面重合，则该表面不存在地转运动，但反之并不成立。本数据集证实，海洋地转流速在z=N处并不为零。数据采用netCDF格式存储。