Application of the Trigonometric Polynomial Interpolation for the Estimation of the Vertical Eddy Viscosity Coefficient Based on the Ekman Adjoint Assimilation Model
Application of the Trigonometric Polynomial Interpolation for the Estimation of the Vertical Eddy Viscosity Coefficient Based on the Ekman Adjoint Assimilation Model
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DOI：
10.3390/jmse10081165
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发表时间：
2022-08
影响因子：
2.9
通讯作者：
Xinping Wu;Minjie Xu;Guandong Gao;B. Yin;Xianqing Lv
中科院分区：
文献类型：
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作者：
Xinping Wu;Minjie Xu;Guandong Gao;B. Yin;Xianqing Lv
本文在带伴随同化的Ekman模型的基础上，提出了一种三角多项式插值（TPI）方法来估计垂直涡动黏度系数（VEVC）。在双胞胎实验中，讨论了在不同因素下使用TPI方法估计VEVC的优缺点。结果表明：(1)TPI方案优于三次样条插值（CSI）和Cressman插值（CI）方案；(2)反演结果对上层观测数据的敏感性高于下层观测数据，TPI方案受缺失数据的影响较小；(3)对于不同的边界层深度，TPI方案的反演结果与给定的分布保持一致；(4)反演结果受观测误差影响较大，TPI方案比CSI和CI方案抗噪能力更强；(5)选择时间风应力阻力系数可以提高TPI方案的反演精度。在实际实验中，利用黄海浮标的观测资料，提出了与TPI方案相结合的Ekman流估计方法。结果表明，该方法能够成功地估计出VEVC，并能获得更精确的电流速度。综上所述，本研究为有效估计VEVC提供了一种有用的方法。
In this study, a triangular polynomial interpolation (TPI) scheme was developed to estimate the vertical eddy viscosity coefficient (VEVC) on the basis of the Ekman model with adjoint assimilation. In the twin experiments, the advantages and disadvantages of estimating the VEVC using the TPI scheme under different factors are discussed. The results indicated that (1) the TPI scheme proves to be better than the cubic spline interpolation (CSI) and Cressman interpolation (CI) schemes; (2) the inversion results are more sensitive to observations from upper ocean layers than those from lower layers, and the TPI scheme is less likely to be influenced by missing data; (3) for various boundary layer depths, the inversion results of the TPI scheme remain consistent with the given distributions; (4) the inversion results can be influenced considerably by observational errors, and the TPI scheme is more resistant to noise than the CSI and CI schemes; and (5) the inversion accuracy of the TPI scheme can be improved by selecting the temporal wind stress drag coefficients. In practical experiments, the adjoint method with the TPI scheme was developed to estimate the Ekman currents by assimilating the observations from a buoy stationed in the Yellow Sea. The results showed the successful estimation of the VEVC and demonstrated that more precise current velocities can be obtained with this estimation scheme. In summary, this study provides a useful approach for the effective estimation of the VEVC.