Researches of Several Aspects on Four-Dimensional Variational Data Assimilation Experiments
Feng Wuhu
(Department of Atmospheric Sciences, Lanzhou University, Lanzhou, 730000,P.R.of China)
It is possible that both observational data error and model error will influence results through four-dimensional variational data assimilation. According to this, some numerical experiments are performed on a shallow water equation model. In these experiments initial data and model error parameter are adjusted simultaneously or sequentially as control variable. It shows when taking initial data as control variable, model error will be aliased to the initial fields if model equations exist error, Although it can be well adjusted during the periods of assimilation, it may not have good forecast after assimilation. But if taking model error parameter as control variable, although model errors will vary with time, we can substitute it with constant model error control if the errors in the model have small effect, otherwise, assimilation will fail. It shows when initial data and model correction term adjusted simultaneous as the control variable, perhaps it will be the best, but the choice of scale will influence the results.
Key words Four-dimensional Variational Data Assimilation Control Varies
Shallow Water Equation Model Adjoint Model