Perturbation of Boundary Conditions to Create Appropriate Ensembles for Regional Data Assimilation in Coastal Estuary Modeling
Perturbation of Boundary Conditions to Create Appropriate Ensembles for Regional Data Assimilation in Coastal Estuary Modeling
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扰动边界条件为沿海河口建模中的区域数据同化创建适当的集合
DOI：
10.1029/2021jc017911
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Inoue Tetsunori
中科院分区：
文献类型：
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作者：
Matsuzaki Yoshitaka;Inoue Tetsunori
利用集合卡尔曼滤波、日本伊势湾的实际观测资料和一个称为伊势湾模拟器的模拟模式，对沿海河口进行了区域资料同化。然后对该方法的适用性和稳健性进行了检验。文中还分析了附加扰动的边界条件与水温、盐度数据同化结果的关系。然后提出了一种通过扰动三个边界条件(大气强迫、侧边界条件[开边界条件]和河流流量强迫)来创建集合的方法。在定点观测到的现场水温和盐度分布每天都被同化。建议的同化方法提供了稳定的数据同化，全年没有水温和盐度的非自然值。此外，对三个边界条件施加扰动不会导致滤波发散，从而表明良好的适用性和稳健性，也就是说，对三个边界条件施加扰动不会退化集合扩散。根据敏感性实验，扰动气温和风速的大气边界条件会增加水温的整体扩散，特别是在近地面层附近。风速对盐度总体扩散的大小影响最大，其主导作用取决于位置。横向边界条件的扰动增加了湾口附近所有水深的水温和盐度的整体扩散，并有效地同化了观测结果。河流量强迫的扰动成功地同化了河口附近的水温和盐度。
Regional data assimilation is conducted for a coastal estuary using the ensemble Kalman filter, real observation data from Ise Bay, Japan, and a simulation model called the Ise Bay Simulator. The applicability and robustness of the method are then examined. We also analyze the relationship between the boundary conditions, which add perturbations and the data assimilation results of water temperature and salinity. A method of creating an ensemble by perturbing three boundary conditions (atmospheric forcing, lateral boundary conditions [open boundary conditions], and river discharge forcing) is then proposed. In situ water temperature and salinity profiles observed at fixed points are assimilated daily. The proposed assimilation method provides stable data assimilation without unnatural values for water temperature and salinity throughout the year. Further, applying a perturbation to the three boundary conditions does not lead to filter divergence, thus indicating good applicability and robustness, that is, applying a perturbation to the three boundary conditions does not degenerate the ensemble spread. According to a sensitivity experiment, perturbing the atmospheric boundary conditions of both air temperature and wind speed increases the ensemble spread of water temperature, especially near the surface layer. Wind speed has the greatest influence on the magnitude of the salinity ensemble spread, and its dominance depends on location. Perturbation of lateral boundary conditions increases the ensemble spread of water temperature and salinity at all water depths near the bay mouth, and the observations are effectively assimilated. Perturbation of river discharge forcing successfully assimilates water temperature and salinity near the estuary.