Making the most of earth observation with data assimilation

An international music company has invested in sophisticated recording equipment, and wishes to make a new recording of a Beethoven Symphony. The Berlin Philharmonic Orchestra is hired, and sound engineers set up high-quality microphones among the players in a recording studio. The orchestra performs and each microphone produces a soundtrack. But only a part of the orchestra can be heard on each soundtrack, some soundtracks are noisy, and some are interrupted by periods of silence due to temporary faults in the equipment. Would the company market the recording as a boxed set of CDs, one CD for each soundtrack? Maybe 'yes' for the few music lovers with expert knowledge and sound equipment who could derive pleasure from such a set. But certainly 'no' for the vast majority who want a continuous high quality, well-balanced blending of sound on a single CD. Like the recording studio, planet Earth now has many very expensive, high-tech recording instruments deployed around it, in this case on satellites. By recording not sound, but electromagnetic signals covering a wide range of frequencies, this web of sensors is providing data of unprecedented quality and scope on the physical, chemical and biological processes occurring in the air, sea and land of the Earth System, a system of profound and far from understood complexity.