Abstract
The Ens-DA community considers a flow-dependent anisotropic error covariance matrix based on ensembles to be an appealing, algorithmically simple alternative to either the current three-dimensional variational data assimilation (3D-VAR) techniques, which use the quasi-isotropic stationary matrix, or four-dimensional variational data assimilation (4D-VAR) techniques, which can be expensive to maintain. The newly implemented NAEFS offers a unique opportunity to link research and operations by providing an operational outlet, delivery mechanism, and ultimate performance measure of all types of THORPEX research for the North American community, and eventually, as NAEFS contributes to the development of the future THORPEX Global Interactive Forecast System, at the international level.
