Two Methods of Global Data Assimilation.

doi:https://doi.org/10.21236/ada155981

Two Methods of Global Data Assimilation.

I. Halberstam,C. T. Johnson,Donald C. Norquist,Sudipta Tung-1984-10-01

1

TL;DRAbstract

Abstract : An optimum interpolation (OI) method and a method that fits observations to basis functions are described. The selected basis functions are the normal modes of the linearized primitive equations. In both methods the assimilation system consists of the analysis procedure, a non-linear normal mode initialization, and the AFGL global spectral NWP model. Both methods were tested using FGGE analyses for 7 Jan 79 OOGMT as the starting point. Successive 12 h assimilations were conducted for ten cycles for the OI and five cycles for the fitting procedure. For the OI method results showed a slight increase in error with time when compared with observations, partly attributable to the 12 h forecast length, which was excessive for the forecast error standard deviation prescribed. The fitting procedure showed significantly stronger error increases with time, due in part to faulty conversion of heights to temperature with the hydrostatic equation and to possible over smoothing by the pro

Chat with Paper

AI Agents for this Paper

Abstract : An optimum interpolation (OI) method and a method that fits observations to basis functions are described. The selected basis functions are the normal modes of the linearized primitive equations. In both methods the assimilation system consists of the analysis procedure, a non-linear normal mode initialization, and the AFGL global spectral NWP model. Both methods were tested using FGGE analyses for 7 Jan 79 OOGMT as the starting point. Successive 12 h assimilations were conducted for ten cycles for the OI and five cycles for the fitting procedure. For the OI method results showed a slight increase in error with time when compared with observations, partly attributable to the 12 h forecast length, which was excessive for the forecast error standard deviation prescribed. The fitting procedure showed significantly stronger error increases with time, due in part to faulty conversion of heights to temperature with the hydrostatic equation and to possible over smoothing by the pro

Keywords

InitializationData assimilationInterpolation (computer graphics)MathematicsSmoothingStandard deviationApplied mathematicsMode (computer interface)

Chat

Click to start Chat