Data assimilation of tides in the Bohai Sea using the adjoint method

Observations of ocean pollutants are usually spatiotemporally dispersive, while it is of great importance to obtain continuous distribution of ocean pollutants in a certain area. In this paper, a dynamically constrained interpolated methodology (DCIM) is proposed to interpolate surface nitrogen concentration (SNC) in the Bohai Sea. The DCIM takes the pollutant transport advection diffusion equation as a dynamic constraint to interpolate SNCs and optimizes the interpolation results with adjoint method. Feasibility and validity of the DCIM are testified by ideal twin experiments. In ideal experiments, mean absolute gross errors between interpolated observations and final interpolated SNCs are all no more than 0.03 mg/L, demonstrating that the DCIM can provide convincing results. In practical experiment, SNCs are interpolated and the final interpolated surface nitrogen distribution is acquired. Correlation coefficient between interpolated and observed SNCs is 0.77. In addition, distribution of the final interpolated SNCs shows a good agreement with the observed ones.

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Numerical Study on Initial Field of Pollution in the Bohai Sea with an Adjoint Method

Mathematical Problems in Engineering ◽

10.1155/2013/104591 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Chunhui Wang ◽

Xiaoyan Li ◽

Xianqing Lv

Keyword(s):

Bohai Sea ◽

Adjoint Method ◽

Numerical Study ◽

Interpolation Method ◽

Marine Ecosystem ◽

Time Step ◽

Initial Field ◽

The Bohai Sea ◽

Pollutant Concentrations ◽

The Stability

Based on the simulation of a marine ecosystem dynamical model in the Bohai Sea, routine monitoring data are assimilated to study the initial field of pollution by using the adjoint method. In order to reduce variables that need to be optimized and make the simulation results more reasonable, an independent grid is selected every four grids both in longitude and latitude, and only the pollutant concentrations of these independent grids needed to be optimized while the other grids were calculated by interpolation method. Based on this method, the stability and reliability of this model were proved by a set of twin experiments. Therefore, this model could be applied in real experiment to simulate the initial field of the total nitrogen (totalN) in May, 2009. Moreover, the distribution of totalN in any time step could be calculated by this model, and the monthly mean distribution in May in the Bohai Sea could be obtained.

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Numerical Study on Initial Field of Chemical Oxygen Demand with Adjoint Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.321-324.252 ◽

2013 ◽

Vol 321-324 ◽

pp. 252-258

Author(s):

Chun Hui Wang ◽

You Li Shen ◽

Xian Qing Lv

Keyword(s):

Chemical Oxygen Demand ◽

Bohai Sea ◽

Adjoint Method ◽

Numerical Study ◽

Marine Ecosystem ◽

Oxygen Demand ◽

Dynamical Model ◽

Three Dimension ◽

Initial Field ◽

The Bohai Sea

Based on the simulation of a marine ecosystem dynamical model in the Bohai Sea, pseudo observations are assimilated to study the initial field of chemical oxygen demand (COD) by using the adjoint method. The three-dimension Princeton Ocean Model (POM) is used to calculate the ambient physical velocities, and only four tidal components (M2, S2, K1 and O1) are taken into account. First a prescribed initial distribution of COD is given. Run the forward model and we can pickup some pseudo observations. Then a set of twin experiments were designed to validate the inversion capability of this ecosystem dynamical model. It was discovered that no matter which form the initial field was, the adjoint method could reduce the misfit between inversion results and observations significantly, indicating that this model was stable and reliable. Therefore, this model could be applied in real experiment to simulate the initial field of COD in the Bohai Sea in future.

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