Satellite earth observation in operational oceanography

The role and contribution of satellite data in operational oceanography is reviewed, with emphasis on northern European seas. The possibility to obser ve various ocean parameters and processes by existing satellite sensors, su ch as optical instruments, infrared radiometers, passive microwave radiomet ers, and active microwave systems (altimeter, scatterometer, SAR) is discus sed. The basic parameters are: sea-surface temperature observed by infrared radiometers, ocean colour by spectrometers, sea-surface elevation by altim eters, and surface roughness by active and passive microwave systems, which can be used to derive surface wind and waves. A number of ocean processes can be derived from synaptic mapping of the basic parameters of larger sea areas, such as current patterns, fronts, eddies, water mass distribution, a nd various water quality parameters (chlorophyll, surface slicks, suspended sediments). The suitability of existing satellite data to fulfil the opera tional requirements for temporal and spatial coverage, data delivery in nea r-real-time, and long-term access to data is discussed in light of the fact that optical/infrared data in northern Europe are severely hampered by fre quent cloud cover, while microwave techniques can provide useful data indep endent of weather and light conditions. Finally, the use of data assimilati on in oceanographic models is briefly summarised, indicating that this tech nique is under development and will soon be adopted in operational oceanogr aphy. (C) 2000 Elsevier Science B.V. All rights reserved.