Ovide 2006: third section between Portugal and Greenland

In collaboration with Herlé Mercier, océanographer at LPO (Laboratoire de Physique des Océans), Brest

This year, Ovide oceanographic campaign is taking place on board the German M. S. Merian research vessel. Departure from Lisbonne (Portugal) on May, 22nd, 2006, arrival is expected in Faeroes Islands on June, 18th, 2006. Hydrographic and geochemistry parameters measurements between the Iberic peninsula and the Greenland are done, in order to study ocean circulation variability in this ocean area of great importance for the European climate.

Ovide campaign path, repeated every 2 years since 2002. Points indicate the positions of temperature/salinity/dissolved Oxygen CTD measurements. Water sampling is made in order to determine geochemical elements concentrations (nutritive salts, pH, alacalinity, CFCs). Credit: Laboratoire de Physique des Océans, Ifremer.

Mercator forecasts on board

Mercator analyses and forecast are used during the campaign to improve sampling strategy. 300 meters PSY2V2 forecast temperature and salinities fields for the 31/05/2006 show perfectly the frontier between the subtropical gyre (warm and salted waters) and the suppolar gyre (cold and not very salted waters). Measurements data are transmitted in real-time to the Coriolis data centre, which is the Mercator in situ data portal. These data are also used to validate and improve Mercator forecast.

300 meters temperature PSY2V2 forecast for the 31/05/2006

300 meters PSY2V2 salinity forecast for the 31/05/2006

The subpolar gyre has an influence on the European climate.

Known by oceanographers as the Atlantic circulation meridian cell, formed by warm and saline tropical waters carried away northwards by the great surface currents, such as the Gulf Stream, the North Atlantic Drift Current, the Norwegian Current, this celle redistributes heat at the eart surface from equator to the poles. This surface movement is counterbalanced by the winter cold downwelling deep waters in the Labrador Sea moving towards the equator.

The subpolar gyre is then supplied with warm waters carried by the Gulf Stream. These waters go along European coasts and induce a warming of oceanic Atlantic crossing air masses circulating above Europe. Variations of this meridian Atlantic cell can perturb both the north European climate and the global climate. In return, atmospheric regimes changes can modify the subpolar and subtropical gyres oceanic circulation.

Measuring oceanic measurments from surface to th bottom (temperature, salinity, currents, carbon and CFC rates, etc.) along a Lisbon-Greenland section, Ovide measures slow Atlantic currents variations, the water masses transformatoin and moving, and carbon and pollutive elements transfer (such as CFC) rom one oceanic basin to another. A first campaign has been held in june 2002. Repeating these campaigns every two years during ten years, Ovide can analyse climatic variations at a few years scale and contribute to the understanding of ocean-atmosphere coupled climatic phenomena (such as the North Atlantic Oscilation, NAO), in the context of the Clivar international programme.

More information:

Herlé Mercier interview, Chief of Ovide campaign, in: projection Mercator, November 2003
Clivar international programme