Four-Dimensional Data Assimilation of GALE Data Using a Multivariate AnalysisScheme and a Mesoscale Model with Diabatic Initialization

摘要

A method of assimilating 3-hourly sounding data is developed and successfullytested in this study. First, the successive corrections scheme of Bratseth (1986), which converges to optimum interpolation, is applied for the numerical analysis of data collected during the Genesis of Atlantic Lows Experiment (GALE). Univariate analyses of the mass and wind field are produced. The coupling of the mass and wind field is achieved by further iterations of the geopotential utilizing improving estimates of the geostrophic wind to extrapolate the geopotential to the grid points. The univariate wind analysis is then corrected for the new geostrophic wind. Next, diabatic forcing is incorporated into a vertical model initialization scheme to provide more realistic initial conditions and to shorten the spinup time of the Naval Research Laboratory/North Carolina State University (NRL/NCSU) mesoscale model. Finally, the multivariate, successive correction analysis scheme and the diabatic initialization procedure are combined with the NRL/NCSU model to form an intermittent data-assimilation system.