Sea level comparison between TOPEX/POSEIDON altimetric data and a global ocean general circulation model from an assimilation perspective
Sea level comparison between TOPEX/POSEIDON altimetric data and a global ocean general circulation model from an assimilation perspective
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DOI：
10.1029/1999jc900044
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发表时间：
1999-07
影响因子：
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通讯作者：
C. Maes;M. Benkiran;P. Mey
中科院分区：
文献类型：
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作者：
C. Maes;M. Benkiran;P. Mey
利用1993年TOPEX/POSEIDON测高海平面观测资料，对海洋动力学和气候学模拟模式（OGCM）进行了全球尺度的模拟验证。强迫场由欧洲中期天气预报中心再分析项目提供。OGCM是一个水平分辨率较低的模式（2°经度× 1.5°纬度，垂直31层），主要用于气候研究。水平混合是沿着等密度面进行的，而垂直混合的参数化是基于湍流动能的局部估计。比较是定量的意义上说，TOPEX/POSEIDON观测插值到模式网格的同化情况下，由一个客观的插值。将模型模拟与500公里或更大空间尺度的观测结果进行了比较。该模型很好地模拟了变率的基本特征，特别是年周期。在西部边界流附近和南大洋发现了重大差异，部分原因是水平分辨率不足。在未来的同化观测到的海平面分解成斜压/正压分量诊断模式的一些动力学变量的模式海平面的预期，然后检查。结果表明，斜压分量解释了大的季节变化局限在上层，而正压分量与季节内变化。本研究的结果证实，模式海平面与观测到的大尺度变化是一致的，提供了一个基础，为未来同化的数据到OGCM，以提高海洋状态的代表性。
The TOPEX/POSEIDON altimetric sea level observations during 1993 are used to validate a simulation made by the Laboratoire d'Oceanographie Dynamique et de Climatologie ocean general circulation model (OGCM) at global scales. The forcing fields are provided by the European Centre for Medium-Range Weather Forecasts reanalysis project. The OGCM is a coarse horizontal resolution model (2° longitude by 1.5° latitude with 31 levels in the vertical), mainly used for climate studies. Horizontal mixing is done along isopycnal surfaces, whereas the parameterization of vertical mixing is based on a local estimate of the turbulent kinetic energy. The comparison is quantitative in the sense that TOPEX/POSEIDON observations are interpolated onto the model grid by an objective interpolation in view of the assimilation case. The model simulation is compared to the observations at large spatial scales of 500 km or more. The basic features of the variability are simulated well by the model, in particular with respect to the annual cycle. Major discrepancies are found in the vicinity of western boundary currents and in the Southern Ocean, due in part to the inadequate horizontal resolution. In anticipation of a future assimilation of the observed sea level a decomposition of the model sea level into baroclinic/barotropic components diagnosed with some dynamical variables of the model is then examined. It is shown that the baroclinic component explains the large seasonal variations confined in the upper layers, whereas the barotropic component is associated with intraseasonal variability. The results of the present study confirm that the model sea level is consistent with the observed large-scale variability, providing a basis for future assimilation of the data into the OGCM to improve the representation of the ocean state.