Numerical experiments of adjoint variational assimilation have been performed using the known Lorenz system.With the increase of sensitivity of model's initial values,it is more and more difficult to use the adjoi...Numerical experiments of adjoint variational assimilation have been performed using the known Lorenz system.With the increase of sensitivity of model's initial values,it is more and more difficult to use the adjoint method to get the initial values which are consistent with the dynamics of the fore- cast model.Under some circumstances the algorithm completely fails.This shows that four-dimen- sional assimilation is related to the limit of predictability.On the other hand.with the increase of model equation's error,the result of variational assimilation may become worse and worse so that the prediction has no meaning.But if the model parameters are corrected when variational assimilation is made,the forecast results can be greatly improved based on Lorenz model.展开更多
基金This work was supported by the National Natural Science Foundation of China under Grant 49375241.
文摘Numerical experiments of adjoint variational assimilation have been performed using the known Lorenz system.With the increase of sensitivity of model's initial values,it is more and more difficult to use the adjoint method to get the initial values which are consistent with the dynamics of the fore- cast model.Under some circumstances the algorithm completely fails.This shows that four-dimen- sional assimilation is related to the limit of predictability.On the other hand.with the increase of model equation's error,the result of variational assimilation may become worse and worse so that the prediction has no meaning.But if the model parameters are corrected when variational assimilation is made,the forecast results can be greatly improved based on Lorenz model.
