MAKING RADAR ALTIMETRY MORE USABLE AND WEB-INTEROPERABLE IN THE COASTAL OCEAN Vignudelli S. (1) , Cipollini P. (2) , Snaith H. M. (2) , Venuti F. (2) , Lyard F. (3) , Bouffard J. (3) , Roblou L. (4) , Cretaux J. F. (3) , Kostianoy A. (5) , Lebedev S. (6) , Mamedov R. (7) (1) Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Area Ricerca CNR San Cataldo, 56127 Pisa, Italy (2) National Oceanography Centre Southampton, European Way, SO14 3ZH Southampton, United Kingdom (3) CNRS-LEGOS, 18 Av. Edouard Belin, 31401 Toulouse Cedex 9, France (4) Noveltis, Parc Technologique du Canal 2, Avenue de l'Europe 31520, Ramonville-Saint-Agne, France (5) P.P. Shirshov Institute of Oceanology, Nakhimovsky Pr. 36, 117997 Moscow, Russia (6) Geophysical Center, Molodezhnaya Str. 3, 119991 Moscow, Russia (7) Institute of Geography, Center for Caspian Sea Problems, H. Javid Str. 31, AZ1143 Baku, Azerbaijan ABSTRACT In this paper, we describe the ALTICORE (value added satellite ALTImetry in COastal REgions) initiative, a consortium aiming at providing high quality coastal altimetry over some European seas. Taking the Ligurian Sea in the NW Mediterranean as an example, which acts as a test zone for this work, we show the improvement in availability and quality of ENVISAT data, through our processing, when compared with the official altimetric products delivered by AVISO. We also introduce the building concepts of solutions for data search, extraction, update and delivery based on web-services. This grid- type infrastructure is being designed in the framework of ALTICORE. 1. THE CONTEXT The natural interface between humans and the oceans is at the coast, and many of the key impacts of the sea on human activities are in the coastal zone. Coastal management often requires decisions to be taken at a level close to that of the people directly affected, i.e. at local or regional level. To act efficiently, managers need fast, reliable access to all available environmental data, both when they are confronted with episodic, unpredictable threats (e.g., storms, pollution events, blooms, etc.) and for long-term planning. In this scenario there is clearly ample scope to assess the ability and performance of existing remote sensing technology closer to the coasts, and investigate the knowledge and benefit that this technology can offer. A case in point is that of altimetry. Information on the ocean surface gathered by the altimeters is used to derive a description of the sea state, through measurements of wave height and wind speed. The altimeter is also the only satellite-borne instrument which returns a measurement (sea surface height) directly related to the internal dynamical state of the ocean. The observed sea surface height variations are related to temperature and salinity changes. They can also provide a measure of currents through the geostrophic relation. These capabilities are provided regardless of weather conditions, especially cloud cover, and in day/night viewing. However, the past and present satellite altimetry missions were not conceived with the coastal ocean in mind, and data in proximity of the coast are normally rejected. This is not only owing to intrinsic limitations of the system but also to the lack of techniques for processing and correction. These data would be extremely important not only for scientific research but also for other socio-economic activities, when assimilated into models of coastal dynamics, sediment transport and pollutant dispersion. While forthcoming altimetric missions such as AltiKa and CryoSat-2 promise much improved capabilities closer to the coast, a current priority is to analyze the existing, under-exploited, 15-year global archive of coastal altimeter data from past and present missions, such as ERS-1 and -2, TOPEX/Posedon, Jason-1, Geosat Follow-On and ENVISAT, both in order to extract all the available information and in order to formulate recommendations and solutions for future missions. This is a key purpose of the ALTICORE (value added satellite ALTImetry in COastal Regions) Project. The present paper describes the structure and organization of the project and illustrates with some examples the methodology for its implementation phase. 2. SATELLITE ALTIMETRY IN THE COASTAL OCEAN The coastal ocean is a complex environment for radar altimetry operation [1]. There are inherent limitations from the technology (e.g.: sampling and coverage) and intrinsic difficulties in processing and interpretation of the data (e.g.: proximity of land, control of seabed, rapid variations due to tides and atmospheric effects); this problem has been common to other remote sensing _____________________________________________________ Proc. ‘Envisat Symposium 2007’, Montreux, Switzerland 23–27 April 2007 (ESA SP-636, July 2007)