Data assimilation and its applications

In data assimilation, one prepares the grid data as the best possible estim ate of the true initial state of a considered system by merging various mea surements irregularly distributed in space and time, with a prior knowledge of the state given by a numerical model. Because it may improve forecastin g or modeling and increase physical understanding of considered systems, da ta assimilation now plays a very important role in studies of atmospheric a nd oceanic problems. Here, three examples are presented to illustrate the u se of new types of observations and the ability of improving forecasting or modeling.