Three-Dimensional Variational Analysis with Spatially Inhomogeneous Covariances

• DOI: 10.1175/1520-0493(2002)130<2905:tdvaws>2.0.co;2
• Publication Date: 2002-11-15T18:18:13Z
• Authors: Wan-Shu Wu; R. James Purser; David F. Parrish
• Keywords: Divergence (linguistics); Variational analysis; Interpolation

In this study, a global three-dimensional variational analysis system is formulated in model grid space. This formulation allows greater flexibility (e.g., inhomogeneity and anisotropy) for background error statistics. A simpler formulation, inhomogeneous only the latitude direction, was chosen these initial tests. The statistics are defined as functions of latitudinal estimated with National Meteorological Center (NMC) method. horizontal scales variables obtained through variances their Laplacian. vertical correlation each variable applied locally using recursive filters. For multivariate between wind mass fields, statistical linear relationship streamfunction balanced part temperature surface pressure assumed. localized velocity potential also used to account positive vorticity divergence planetary boundary layer. Horizontally, domain divided into three pieces so that efficient spatial filters can be spread out information from observation locations. tested against operational Spectral Statistical-Interpolation at Centers Environmental Prediction. results indicate 3DVAR physical space effective spectral extratropics yields superior Tropics result dependence