Abstract: A two-layer Gulf Stream model is considered. We assume no motion in the lower layer and a basic state zonal jet in the upper. The purpose of the study is to examine numerically the validity of hydrodynamic stability ...

Abstract: Ageostrophic effects on the stability properties of a frictionless adiabatic atmosphere are investigated. The neutral stability boundary is found to consist of the range of variation in the basic state zonal speed. It is ...

Abstract: Variational four-dimensional data assimilation, combined with a penalty method constraining time derivatives of the surface pressure, the divergence, and the gravity-wave components is implemented on an adiabatic version ...

Abstract: Variational four-dimensional (4D) data assimilation is performed using an adiabatic version of the National Meteorological Center (NMC) baroclinic spectral primitive equation model with operationally analyzed fields as ...

Abstract: Cost functions formulated in four-dimensional variational data assimilation (4DVAR) are nonsmooth in the presence of discontinuous physical processes (i.e., the presence of ?on?off? switches in NWP models). The adjoint ...

Abstract: No abstract available.

Abstract: A number of improvements were implemented on 6 March 1991 into the National Meteorological Center's global model, which is used in the global data assimilation system (GDAS), the aviation (AVN) forecast, and the medium-range ...