Improving ocean tides by constraining the dynamic HAMTIDE model with altimetry an GRACE data

通过高度测量和 GRACE 数据约束动态 HAMTIDE 模型来改善海洋潮汐

• 批准号: 192240048
• 负责人: Professor Dr.-Ing. Reiner Rummel
• 金额: --
• 依托单位: Centrum für Erdsystemforschung und Nachhaltigkeit (CEN)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/192240048?language=en
• 关键词: Improving; ocean; tides; constraining; dynamic

The proposed effort of improving global ocean tide models through the assimilation of tidal information available from altimetry and GRACE data is of central concern for the SPP 1257 “Massentransporte und Massenverteilungen im System Erde” and is necessary to improve GRACE and GOCE gravity field modeling (to avoid aliasing). At the same time the effort will improve our knowledge about the role of tide in the general circulation of the ocean. Global ocean tide models describe short term ocean mass variations, quantify loading effects for stations on land, explain parts of the variations observed in Earth rotation, and are required for correcting altimetric sea surface heights and for GRACE and GOCE gravity field modeling (dealiasing). Equally important, tidal friction, mainly in the shallow seas, contribute to mixing the ocean, and exerts influence on the angular momentum and hence on the length of the day. Moreover, the internal wave drag caused by interaction of barotropic tidal currents with topography induces generation of the internal tides in the deep ocean. Such conversion of the mechanical energy into the internal tides is important for the abyssal ocean mixing to maintain the general ocean circulation (nearly steady-state process). Other important features of the tides are their influence on the solid Earth deformation (loading and self-attraction effect) and on the variation of the gravitational fields, consequently on the variation of the satellite orbits. Improving our understanding of ocean tides and expanding our insight into tidal currents, tidal energy transfer or dissipation is therefore an O(1)-problem to physical oceanography and the geodetic community alike. Improved estimates of ocean tides, beyond what we can learn from empirical tide models, can be obtained by constraining dynamical tide models by observed tidal information. The dataassimilative model HAMTIDE, which is used in this project, has already proven valuable and capable of modelling ocean tides during the first two funding periods of DAROTA. The high quality of the dynamical solution is obtained through an effective method by which the model is being constrained by surface tide information (water elevation defined by the altimetry as well as data inferring tidal currents). Results can be used for detecting rates and generation sites of the surface-to-internal tide conversion, finding regions of the tidally induced vertical mixing, and consequently influence on the climate, i.e., an important link from satellite signals to climate variations. In the next phase, the gravimetry (GRACE, GOCE) and altimetry (T/P, ICESat, CRYOSAT2) data will be used simultaneously as constraints in the assimilation process. This will improve tidal estimates not only in low and mid-latitudes where altimetry is available, but also in high latitudes where better tide models are needed to improve gravity field retrievals. The first result of this kind of data assimilation (with coarse resolution and few gravimetry data) is highly promising. Results will be used for an improved understanding of tidal dissipation (see also the figure on the title page and the attached draft paper Taguchi, Stammer and Zahel, 2010). Results will likewise be intercompared with all state of the art global tide models as part of the proposed effort.

通过吸收来自高度测定和宽限数据的潮汐信息，提出的努力是SPP 1257“ MassentRansporte and Massenverteleilungen im System Erde”的核心关注点，这对于改善宽限度和Goce Gravity Gravity Field Field Field Field Field Field Modeling（以避免同行）是必不可少的。同时，这项努力将提高我们对潮汐在海洋一般循环中的作用的了解。全球潮汐模型描述了短期海洋质量变化，陆地上站点的数量负载效应，解释在地球旋转中观察到的变化的一部分，并且是校正高度海面高度以及Grace and Goce Goce Gravity Field Field Modeling（Dealiasing）所必需的。同样重要的，潮汐摩擦，主要是在浅海中，有助于混合海洋，并对角动量施加影响，从而对一天的长度产生影响。此外，由压缩潮流与地形的相互作用引起的内波阻力会引起深海内部潮汐的产生。这种机械能向内部潮汐的转化对于深渊海洋混合以维持一般的海洋循环（几乎稳态过程）很重要。潮汐的其他重要特征是它们对固体地球变形（负载和自动吸引效应）的影响以及对重力场的变化，因此对卫星轨道的变化。因此，我们对海洋潮汐的理解提高了，并扩大了对潮流的洞察力，潮汐能量转移或耗散是O（1） - 物理海洋学和大地测量社区的问题。通过观察到的潮汐信息来限制动态潮汐模型，可以从经验潮汐模型中获得的改进的海洋潮汐估计值，超出了我们可以从经验潮汐模型中学到的估计。在该项目中使用的数据密码模型HAMTIDE已经证明了价值，并且能够在Darota的前两个资金期间对海潮进行建模。动态溶液的高质量是通过一种有效方法获得的，该方法通过表面潮汐信息（由高度测定法以及推断潮流的数据定义的水位）来限制该模型。结果可用于检测表面至内部潮汐转换的速率和生成位点，找到潮汐诱导的垂直混合的区域，并对气候产生影响，即，从卫星信号到气候变化的重要联系。在下一个阶段，重量表（宽限期，goce）和高度测定（T/P，ICESAT，CRYOSAT2）数据将简单地用作同化过程中的约束。这将不仅可以在可用的高度测定法的低纬度和中纬度中改善潮汐估计，而且还可以在需要更好的潮汐模型来改善重力场检索的高纬度估计中。高度承诺，这种数据同化的第一个结果（具有粗分辨率和很少的重量表数据）。结果将用于改进对潮汐耗散的理解（另请参见标题页上的图以及所附的纸塔格奇（Taguchi），Stammer和Zahel，2010年）。作为拟议努力的一部分，结果同样将与所有最先进的全球潮汐模型相对应。