The oceans, which cover about 70 per cent of the earth' surface, will be one of our most important natural resources in the future.
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Background: The oceans, which cover about 70 per cent of the earth' surface, will be one of our most important natural resources in the future. Therefore, it is necessary to have a global monitoring system to improve our management of the sea.
The National Aeronautics and Space Administration (NASA) of the United States will launch the NIMBUS-G satellite in fall 1978. This spacecraft will carry a data acquisition system called the Coastal Zone Colour Scanner which is designed to obtain information about off shore coastal areas.
The Joint Research Centre of the European Communities, situated in Ispra in North Italy, was invited to participate in the Coastal Zone Colour Scanner experiment ad proposed a study on a number of European coastal test sites with participation from all member states of the Community.
The project was named EURASEP - an abbreviation for European Assessment of Pollution.
Studies of ocean colour and ocean dynamics as related to substances in the water by means of specialized spaceborne instruments is a new approach in the attempt to monitor our marine environment. Therefore, NASA built an instrument called the Ocean Colour Scanner which - when operated from high flying aircraft - can simulate the performance of the Coastal Zone Colour Scanner on board the NIMBUS-G satellite.
The data acquired by the Ocean Colour Scanner over American and European test ides will be correlated with simultaneous measurements in the water from ships, and treatment and analysis of this data will eventually enable the scientists to set the standards for the measurement program which shall support the data from the Coastal Zone Colour Scanner.
The major European contribution to this prelaunch program is the
The Ocean Colour Scanner is an optical and electronic device, built for detection and recording of reflected sun light from the ocean water and particles in the water.
It records 10 different colours on magnetic tape. This data can later be reproduced on film or transferred to computer compatible tapes for analysis.
To analyze the coastal colour maps, made from the OCS data, it is necessary to correlate the colours with identified types and quantities of particles and dissolved chemicals in the water. This is achieved through measurements taken in the water, and laboratory analysis of water samples collected from ships simultaneous with the overflight.
The atmospheric layer between the aircraft that carries the scanner and the ocean surface forms the major part of the signal. Less than 10 per cent of the light recorded by the scanner comes from the water and the particles suspended in the water. The rest is scattered light from water vapour, dust particles and air molecules. it is therefore necessary to make special measurements to compensate for the atmospheric effect.
The OCS experiment is a complex project which requires expertise in many scientific disciplines. Oceanographers, biologists, physicists, engineers and mathematicians from all member states of the European Communities are involved in the collection, processing and analysis of the data.
It is in this spirit of international cooperation that the solution to improved management of our ocean has to be found.
The operation which took place on June 29th spread from Holland to Northern France. The coordination centre was the North Sea directorate in the Hague.
Nine boats left the coast on a route perpendicular to the coast line. 2 french from Caliss and Dunkerque, 2 belgians from Ostende and Zeebrugge. 1 british from Schouwen island in Holland, the rest of them dutch from Hoek Van Holland (2 boats on different traverses), Vlissingen and Scheveningen, 2 platform belonging to the dutch north sea directorate took also part in the sampling and measurements. On the boats scientific teams from Britain, Germany, France, Italy, Ireland, Nederland, Belgium. the coordinator of the operation is Benny Sorensen, danish, from Ispra's Joint Research Centre of the European Communities. Manning the scanner loaned by Nasa aboard the french Mystere 20 of the "Institute Geographic National" is Pr. Sorel of Luxembourg.
3 atmospheric measurements teams: 2 german (Zeebrugge and Valkenburg airport near the Hague) and one italian from Ispra on Schouwen island. These teams work on land and take measurements which will compensate the reading of the Scanner affected by atmospheric perturbations.
The boats leave all together and start continuous surface sampling while on course on their traverse through a device floating near the boat and towed. The water goes thru various instruments measuring chlorophyll, turbidity, salinity, temperature to 0.1 degree C. The mystere 20 has taken off a little after the boats left and flies over head (see map) at 11000 metres. The scanner sweeps an area wide of 18km, taking images of the measured areas. Each boat has to be stationary when the mystere is approximately overhead ad water samples are then taken and kept in bottles for further lab analysis. The most important point in the sampling is to note the precise location and time when the samples were taken to compare with the corresponding image of the scanners' datas.
At the two platforms datas are as well recorded and go directly to the data receiving room of the North Sea directorate in the Hague.
At the same time the atmospheric measurements team take precise measurements of the layer between the aircraft and the sea to correct the images obtained.
Later the water samples are analyzed in a lab and datas are used to calibrate the images received by the OCS.