Abstract: This paper is concerned with the weakly nonlinear inviscid dynamics of a marginally unstable baroclinic wave near the point of minimum critical shear of a two-layer quasi-geostrophic model on the ?-plane. In previous studies ...

Abstract: One of the objectives of data assimilation is to produce initial conditions that will improve the quality of forecasts. Studies on singular vectors and sensitivity studies have shown that small changes to the initial ...

Abstract: egional and global climate models are usually validated by comparison to derived observations or reanalyses. Using a model in data assimilation results in a direct comparison to observations to produce its own analyses ...

Abstract: In this paper, a weak constraint formulation of the digital filter based on the Dolph?Chebyshev window is introduced in a preoperational version of the 4DVAR analysis of Météo-France. The constraint is imposed only on the ...

Abstract: bserving system experiments (OSEs) are commonly used to quantify the impact of different observation types on forecasts produced by a specific numerical weather prediction system. Recently, methods based on degree of freedom ...

Abstract: The tangent linear model (TLM) is obtained by linearizing the governing equations around a space- and time-dependent basic state referred to as the trajectory. The TLM describes to first-order the evolution of perturbations ...

Abstract: his study examines the assimilation of near-surface wind observations over land to improve wind nowcasting and short-term tropospheric forecasts. A new geostatistical operator based on geophysical model output statistics ...

Abstract: The object of this paper is to present some results obtained with an extended Kalman fitter (EKF). First, a discussion is given of the way that the EKF has been implemented and tested for a global nondivergent barotropic ...

Abstract: The degrees of freedom for signal (DFS) is used in data assimilation applications to measure the self-sensitivity of analysis to different observation types. This paper describes a practical method to estimate the DFS of ...