Sea Technology

MAR 2013

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Page 30 of 71

The Campos confguration comparison with drifter data and current module (top) and direction (bottom). weather conditions (although cloud cover can be an issue). Satellite data time coverage is also better, as the data are often continuous, with time series going back as far as 20 years. In addition, the resolution of satellite data is very high and able to reach down to a few meters for synthetic aperture radar imagery, although it is often in the range of a few kilometers for most products. Furthermore, the near-real-time delivery of the data takes a few hours, which is quicker than the characteristic time scales of many ocean phenomena. Two aspects of the data determine its suitability for use by the HCS: quality and availability in real and near-real time, and in forecast modes. Hence, if consistent with the HCS���s needs, priority is given to these data sets in operational mode. There are three types of data used in the production of the HCS currents. Satellite Data. Satellite data are used to provide information on the large-scale circulation (altimetry data, often from CLS���s Aviso Web server) through the geostrophy calculation. It is also used to give information on the small-scale features, such as sea surface temperature and ocean color data, through the surface quasigeostrophic approach. Sea surface temperature and ocean color data are operationally produced at CLS. Model Data. Three types of model data are used in the HCS: Ocean, atmospheric and tidal. Ocean model data provide boundary conditions and information on the large-scale veloc- ity intensity distribution, often from the Mercator Ocean (Ramonville-St.Agne) model but also from regional models when available. These operational models use in-situ observation and along-track satellite data, such as altimetry. Atmospheric data are used to calculate the wind-driven part of the fow, often from the European Centre for Medium-Range Weather Forecasts (ECMWF) model and from available local confgurations. Tidal model data from a global CLSrun tidal model gives the tidal currents. In-Situ Data. Ocean in-situ data from ADCPs, rotor current meters or drifting foats are used to confgure and validate an HCS confguration. CLS has developed and maintains a database of all available drifters��� data from France���s Coriolis data center or Argo foat program. Atmospheric in-situ data can be used by the HCS to determine the wind-driven part of the circulation. MARCH 2013 / st 31

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