简介：Thispaperfirstdevelopstheapproachestodeterminethegeopotentialofthelocalmeansealevel,andtheninvestigatestheoffsetofthe1985verticaldatumsurfacedefinedbythemeansealevelofYellowSeaattheDagangTideGaugeinQingdaocityusingthedevelopedapproachesandGPS/levelingdata.Itshowsthatthegeopotentialofthelocalmeansealevelatthetidegaugeisequalto62636853.5±0.2m2*s-2andthatthe1985verticaldatumsurfaceis24.6±5.4cmabovethegeoidrealizedbythegeopotentialW0=62636856.0±0.5m2*s-2.

简介：Anewmethodologyforprecisegeoiddeterminationwithfinestlocaldetailsbasedonellipsoidalapproximationispresented.Thismethodologyisformulatedthroughthe'fixed-freetwo-boundaryvalueproblem'basedontheobservableofthetypemodulusofgravityintensity,gravityaccelerationandgravitypotentialattheGPSpositionedstations,withsupportoftheknowngeoid'spotentialvalue,W0.