The equatorial surface velocity field derived from satellite altimeter observations

总体目标是改进目前用于确定赤道表面速度场的方法。希望这将有助于海洋表面洋流分析实时(OSCAR)项目和海洋和水文地形中心(CTOH)的产品。对OSCAR计划和CTOH产品提供的全球表面速度场的研究表明，赤道区的速度，特别是其经向分量，与现场观测结果不太一致。主要原因可能是，目前用于计算与SSH有关的速度的方法基本上是基于地转平衡的，尽管赤道地区的地转平衡被打破了。本研究将使用基于地转平衡关系的准地转模式，而赤道模式则基于不同的平衡关系。这些平衡关系将被用来代替地转平衡关系来确定与赤道地区SSH有关的速度。海洋模式将被用来研究它的赤道SSH场的性质，解决所提出的平衡关系的各种算法，对参数选择的敏感性，以及结果的准确性。一旦对可能的最佳方法及其特性有了很好的了解，将对卫星高度计观测进行同样的调查，并调查其他问题，如误差。该项目旨在提高赤道地区全球地表速度场的精度。因此，这提高了它对它已经帮助调查的问题的适用性，从石油泄漏到水平平流对地表热量收支的作用。例如，提高全球地表速度场的精确度将改善地表热量收支的研究，这反过来又与气候研究有关。该项目还将继续开展教育活动，使美国的本科生和研究生有机会获得东非沿海海洋学的国际研究经验。

The overall objective is to improve the current methods used to determine the equatorial surface velocity field. It is hoped that this will be of benefit to the Ocean SurfaceCurrent Analyses Real time (OSCAR) project and the Centre de Topographie des Oceans et del'Hydrosphµere (CTOH) product. Studies of the global surface velocity field provided by the OSCAR project and the CTOH product have shown that the velocities in the equatorial region, especially their meridional components, do not agree well with in situ observations. The main reason could be that the current methods used to calculate the velocity, which is related to SSH, are essentially based on geostrophic balance, although geostrophic balance breaks down in the equatorial region. This study will use a quasi-geostrophic model, which is based on the geostrophic balance relations, whereas its equatorial counterpart is based on different balance relations. These balance relations will be used in place of the geostrophic balance relations to determine the velocity that is related to SSH in the equatorial region. An ocean model will be used to investigate the properties of its equatorial SSH field, various algorithms that solve the proposed balance relations, the sensitivity with respect to parameter choices, and the accuracy of the results. Once a good understanding will have been developed about the best possible methods and their properties, the same investigation will be carried out with satellite altimeter observations, and additional issues such as errors investigated. The proposed project aims at improving the accuracy of global surface velocity field in the equatorial region. This thus improves its applicability to issues that it already helps to investigate, ranging from oil spills to the role of the horizontal advection on the surface heat budget. Improving the accuracy of the global surface velocity field will improve for instance the study of the surface heat budget, which in turn is relevant for climate studies. The project will also continue the educational activity of giving undergraduate and graduate students in the United States the opportunity to obtain an international research experience in coastal oceanography in East Africa.