Direct assimilation of satellite radiance data in GRAPES variational assimilation system

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...

Variational assimilation of Lagrangian data in oceanography

We consider the assimilation of Lagrangian data into a primitive equation circulation model of the ocean at basin scale. The Lagrangian data are positions of floats drifting at fixed depth. We aim at reconstructing the fourdimensional space-time circulation of the ocean. This problem is solved using the four-dimensional variational technique and the adjoint method. In this problem the control v...

Improved variational methods in statistical data assimilation

Data assimilation transfers information from an observed system to a physically based model system with state variables x(t). The observations are typically noisy, the model has errors, and the initial state x(t0) is uncertain: the data assimilation is statistical. One can ask about expected values of functions 〈G(X)〉 on the path X={x(t0), . . .,x(tm)} of the model state through the observation...

Mesoscale Variational Assimilation of Profiling Radiometer Data

Retrieved profiles of temperature, water vapor, and cloud liquid water are obtained through neural net inversions of the brightness temperatures, where the neural net is trained using radiosonde soundings and corresponding forward modeled brightness temperatures. An observation operator has also been developed for the direct assimilation of the measured brightness temperatures, using the forwar...

Constrained adaptive bias correction for satellite radiance assimilation in the ECMWF 4D-Var system