Sensitivity of regional ensemble data assimilation spread to perturbations of lateral boundary conditions

Sensitivity in ranking for perturbations of data in DEA

Application of Lateral Boundary Condition Perturbations to Help Restore Dispersion in Limited-Area Ensemble Forecasts

In a previous companion paper, the authors showed that lateral boundary condition (LBC) constraints on small scale error variance growth are sufficient to limit dispersion in limitedarea model (LAM) ensemble simulations. The error growth constraints result from the use of coarsely resolved and temporally interpolated LBCs. The effect is present in any modeling system using “one-way” LBC forcing...

A review of operational methods of variational and ensemble-variational data assimilation: Ensemble-variational data assimilation

Variational and ensemble methods have been developed separately by various research and development groups and each brings its own benefits to data assimilation. In the last decade or so, various ways have been developed to combine these methods, especially with the aims of improving the background-error covariance matrices and of improving efficiency. The field has become confusing, even to ma...

Boundary Conditions for Singular Perturbations

Let A : D(A) H ! H be an injective self-adjoint operator and let : D(A) ! X, X a Banach space, be a surjective linear map such that k k X c kAAk H. Supposing that Range (0) \ H 0 = f0g, we deene a family A of self-adjoint operators which are extensions of the symmetric operator A jf =0g. Any in the operator domain D(A) is characterized by a sort of boundary conditions on its univocally deened r...

Ensemble-based atmospheric data assimilation

Ensemble-based data assimilation techniques are being explored as possible alternatives to current operational analysis techniques such as threeor four-dimensional variational assimilation. Ensemble-based assimilation techniques utilise an ensemble of parallel data assimilation and forecast cycles. The background-error covariances are estimated using the forecast ensemble and are used to produc...