The DTU 2022 Mean Dynamic Topography models

The mean dynamic topography (MDT) describes the differences between the time-mean sea surface and the geoid and reflect the mean circulation in the oceans. In this analysis the so-called geodetic mean dynamic topography model DTU22MDT is derived using the recent DTU21MSS mean sea surface. As geoid model the XGM2019e model complete to d/o 2160 was applied. The processing scheme used for deriving the geodetic MDT is based on spatial filtering for reducing errors. Subsequently, drifter velocities from in-situ buys are integrated to enhance the resolution of the MDT model. The final model DTUUH22MDT provide a state-of-the-art description of the 20 year mean global ocean circulation.Further information on the methodology may be found in:Knudsen, P., Andersen, O.B., and Maximenko, N., 2021. A new ocean mean dynamic topography model, derived from a combination of gravity, altimetry and drifter velocity data. Advances in Space Research, Volume 68, Issue 2, 1090-1102.The models are available inGRAVSOFT grid format (in ascii)XYZ ascii file format

平均动力地形（mean dynamic topography, MDT）指时间平均海面与大地水准面（geoid）之间的差值，可反映海洋的平均环流状态。本研究依托最新发布的DTU21MSS平均海面数据集，构建了大地测量型平均动力地形模型DTU22MDT。本次研究采用截至球谐展开阶次2160的XGM2019e模型作为大地水准面模型。用于推导该大地测量MDT的处理流程以空间滤波技术为核心，用以降低计算误差。后续，研究团队通过整合原位漂流浮标的速度观测数据，进一步提升了MDT模型的空间分辨率。最终得到的DTUUH22MDT模型，可对20年平均的全球海洋环流进行当前最高水准的刻画与描述。有关该研究方法的更多细节可参阅以下文献：Knudsen P、Andersen O B 及 Maximenko N 于2021年发表的《结合重力、测高与漂流浮标速度数据构建的新型海洋平均动力地形模型》一文，刊载于《空间研究进展（Advances in Space Research）》第68卷第2期，页码范围1090-1102。本模型提供GRAVSOFT网格格式（ASCII）及XYZ ASCII文件格式两种数据存储形式。