简介：NumericalexperimentsofadjointvariationalassimilationhavebeenperformedusingtheknownLorenzsystem.Withtheincreaseofsensitivityofmodel’sinitialvalues,itismoreandmoredifficulttousetheadjointmethodtogettheinitialvalueswhichareconsistentwiththedynamicsofthefore-castmodel.Undersomecircumstancesthealgorithmcompletelyfails.Thisshowsthatfour-dimen-sionalassimilationisrelatedtothelimitofpredictability.Ontheotherhand.withtheincreaseofmodelequation’serror,theresultofvariationalassimilationmaybecomeworseandworsesothatthepredictionhasnomeaning.Butifthemodelparametersarecorrectedwhenvariationalassimilationismade,theforecastresultscanbegreatlyimprovedbasedonLorenzmodel.