On the 4D variational data assimilation with constraint conditions

An investigation is carried out on the problem involved in 4D variational d ata assimilation (VDA) with constraint conditions based on a finite-element shallow-water equation model. In the investigation, the adjoint technology , penalty method and augmented Lagrangian method are used in constraint opt imization field to minimize the defined constraint objective functions. The results of the numerical experiments show that the optimal solutions are o btained if the functions reach the minima, VDA with constraint conditions c ontrolling the growth of gravity oscillations is efficient to eliminate per turbation and produces optimal initial field, It seems that this method can also be applied to the problem in numerical weather prediction.