Variational Identification of Input Parameters in the Model of Distribution of the Pollutants from the Underwater Source

Abstract

Purpose. The aim of the paper is to construct and to validate the variational procedure for determining the pollutant concentration and the water flow out velocity at the underwater source exit, as well as to analyze the algorithm sensitivity to the level of random noise in the measurement data. Methods and Results. The flow field was calculated using the three-dimensional baroclinic σ-coordinate model of water circulation. Realization of the pollution transfer model included application of the TVD-type monotone schemes. The temperature and salinity initial profiles were preset based on the results of probing in the area of the underwater release, and the characteristic velocity of the back-ground currents was defined using the data of the ADCP-measurements. The input parameters of the problem were identified by means of the iterative procedure for minimizing the quadratic functional. The numerical experiments on identifying parameters of the underwater pollution source showed that if noise was left out of account, the original parameters were reconstructed with a relative error < 1%. It is shown that the identification problem becomes of better conditionality in case the data from more informative points of the measurement scheme are assimilated. Conclusions. Based on the analysis of the numerical experiments, the linearization algorithm is shown to be able to identify the parameters of the underwater source. The proposed algorithms can be used to solve a wide class of environmental problems, as well as to interpret and to plan the field experiments aimed at studying the wastewater distribution in the coastal waters.