Assimilation of Earth rotation parameters into a global ocean model: excitation of polar motion
Assimilation of Earth rotation parameters into a global ocean model: excitation of polar motion
复制标题
将地球自转参数同化到全球海洋模型中：极移的激发
DOI：
10.5194/npg-18-581-2011
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发表时间：
2011
影响因子：
2.2
通讯作者：
J. Schröter
中科院分区：
文献类型：
--
作者：
J. Saynisch;M. Wenzel;J. Schröter
抽象的。海洋对地球自转异常的贡献是多方面的。可能的原因是海洋总质量的变化、海流速度或位置的变化以及质量分布的变化。为了得到海洋地球自转激发的物理机制，我们同化地球自转观测与全球环流海洋模式。在同化之前，日长和极移的观测被转换成海洋角动量的估计。通过使用伴随4D-VAR同化方法，我们能够重现这些估计的时间序列。虽然同时同化了日长，但本文的分析重点是海洋极移的产生。我们的研究结果表明，质量分布和电流的变化有助于海洋极地运动的产生。这两种贡献是高度相关的，并显示出相似的幅度。同化过程对模式的改变可能与大气强迫的变化有关。由于几何上的原因，海洋总质量的变化并不投射到极移上，我们得出极移主要是由大气动量强迫的地转响应产生的结论。在地转流中，质量位移和流速相互依存。这样可以解释质量和海流产生的海洋角动量的巨大相似性。
Abstract. The oceanic contribution to Earth rotation anomalies can be manifold. Possible causes are a change of total ocean mass, changes in current speed or location and changes in mass distribution. To derive the governing physical mechanisms of oceanic Earth rotation excitation we assimilate Earth rotation observations with a global circulation ocean model. Before assimilation, observations of length of day and polar motion were transformed into estimates of ocean angular momentum. By using the adjoint 4D-VAR assimilation method we were able to reproduce these estimated time series. Although length of day was assimilated simultaneously the analysis in this paper focuses on the oceanic polar motion generation. Our results show that changes in mass distribution and currents contribute to oceanic polar motion generation. Both contributions are highly correlated and show similar amplitudes. The changes in the model done by the assimilation procedure could be related to changes in the atmospheric forcing. Since for geometrical reasons the change of total ocean mass does not project on polar motion, we conclude that the polar motion is mainly generated by a geostrophic response to atmospheric momentum forcing. In geostrophic currents mass displacement and current speed entail each other. This way the large similarity of mass and current generated ocean angular momentum can be explained.
将地球自转参数同化到全球海洋模型中：日激励长度
影响因子：
4.4
作者：
Saynisch;Wenzel;Schröter
通讯作者：
Schröter