Measurement of sea surface currents with satellites to benefit Swedish GMES marine core services
Why are sea surface currents important?
Realistic and reliable models of ocean circulation are important in order to increase our knowledge about internal processes in the Baltic Sea and about exchange with the North Sea and the northern Atlantic. At SMHI circulation models are used to drive drift forecasts for sea ice, blooming algae, oil spill and search and rescue. These operational services require circulation models with high precision and accurate surface currents. For ecological models the transport of nutrient and hazardous substances are important. Flows and transports in key areas in the Baltic Sea, e.g. the Stockholm Archipelago, the Gulf of Finland and the Bay of Gdansk, are not satisfactory mapped. Information about currents is also important for optimization of fuel consumption in the shipping industry and for risk assessment and action plans before building wind parks, bridges and other constructions that might affect the flow of water.
Why use satellite measurements?
With the help of observations and measurements of sea surface currents, error margins in the models can be estimated, model weaknesses can be identified and the precision in drift forecasts can be increased. SMHI only operate two buoys in Swedish waters and there are no suitable coastal radars, so there is a strong need for more observations. However, new satellites and recent development of methods and algorithms have increased the possibility to measure sea surface currents with satellites.
Objectives and methods
The main areas of interest are the Baltic Sea, Öresund, Kattegatt and Skagerak and the objectives of the project are to:
• Evaluate available and new methods and algorithms to retrieve information about sea surface current from satellite data.
• Determine the operational usefulness of information about sea surface current from satellite data for Swedish GMES marine core services.
• Increase the awareness among Swedish maritime service providers about the possibilities and limitations regarding information about sea surface current from satellite data.
The main satellite sensors to be used will be radiometers (AVHRR) and the imaging radars on the satellites ENVISAT, TerraSAR-X and TanDEM-X. To collect validation data, one or more field campaigns will be organized together with international partners.