#AS2018
Earth System Assimilation
In 2018 it is 20 years since the original introduction of 4D-Var at ECMWF. 4D-Var has brought many very significant benefits over the past 20 years. In recent years the importance of having an ensemble component to the data assimilation has also become apparent and effort has focussed on optimising the ensemble configuration, including hybrid techniques. The 2018 Annual Seminar will present the state of the art in data assimilation methods as applied in different Earth system components, as well as progress and strategies for coupled data assimilation. In particular the Seminar will give an opportunity to report and identify common themes in assimilation for different Earth system components (atmosphere, including composition; land; ocean; and cryosphere) with a particular emphasis on coupling. The Seminar will also present the status and evolution of the global observing system for Earth system assimilation.