Climate reanalysis

ECMWF periodically uses its forecast models and data assimilation systems to 'reanalyse' archived observations, creating global data sets describing the recent history of the atmosphere, land surface, and oceans. The essence of this process, which provides consistent and convenient 'maps without gaps', is explained in this animation.

Reanalysis is very popular and is used for monitoring climate change, for research and education, and for commercial applications.