Abstract: The normal modes of a linearized discrete-time model have been determined. The model is spectral and global. Although the model actually uses the primitive equations, only the equivalent systems of shallow water equations ...

Abstract: We examine some properties of the extratropical atmosphere which act to maintain quasi-geostrophic balance. A nonlinear, f-plane, primitive equation, two-layer model is used. The momentum and temperature fields are described ...

Abstract: Ageostrophic effects on geostrophic motions are examined for f-plane flows characterized by small Rossby numbers. For small Rossby numbers, the ageostrophic field is determined by the geostrophic field through the familiar ...

Abstract: Several numerical weather prediction models now use nonlinear normal-mode initialization schemes. These schemes describe balanced states which act to limit the initial presence of high-frequency gravity waves and their ...

Abstract: The degrees to which mesoscale model simulations satisfy forms of the quasi-geostrophic omega-equation and nonlinear balance equation are determined for various vertical and horizontal scales. The forms of the equations ...

Abstract: The convergence properties of Machenhauer?s nonlinar normal-mode initialization scheme are explored. Only adiabatic initialization is considered. Several models are used, including an f-plane model. a numerical weather ...

Abstract: A method is presented for determining variance spectra of meteorological fields specified on limited-area grids. Spectra so obtained are compared with global spectra of the same data. An example of scale decomposition ...

Abstract: The limited-domain, spectral analysis schemes or Errico and of Barnes are compared. They differ in their treatments of aperiodicity of the domain boundaries. The difference is shown to strongly affect treatment of the ...

Abstract: A global, spectral model developed at the National Center for Atmospheric Research is investigated. It is first demonstrated that some of the model's normal modes tend toward an approximate dynamical balance. This is shown ...

Abstract: Some basic aspects related to the problem of incorporating moist convective processes in a variational data assimilation framework are considered. The methodology is based on inverse problem theory and is formulated in its ...