Ongoing and planned efforts in the Atlantic relevant for CLIVAR and GOOS - a European perspective
Uwe Send
Institut fuer Meereskunde an der Universitat Kiel
Various projects using acoustic tomography techniques are being planned or under way in the North Atlantic Ocean. On ongoing multi-year process study involves sensing of the convection activity in the Labrador Sea, in order to detect and understand multi-year variability of this process and its effect on the thermohaline circulation. This is part of a German special research initiative ("SFB") which has the topic of the "Dynamics of thermohaline circulation variability".
The recent joint IFM/SIO pilot experiment in the Strait of Gibraltar demonstrated that the outflow transport can be monitored acoustically with coast-to-coast transmissions. Plans are under way to submit a proposal to the new European funding cycle for starting the setup of a permanent shore-based acoustic monitoring system in this important strait. This is interesting on its own for observing how steady the outflow from the Mediterranean is, but would also become an important element of a Mediterranean GOOS system (constraint or boundary condition for models of the basin interior).
A German CLIVAR project has been approved to monitor the thermohaline overturming circulation in an integral sense at a well suited location in the Carribean Sea. This would initially only involve non-acoustic (geostrophic) integral measurements of the transport between the coast and the Mid-Atlantic Ridge. However, in the second year the addition of a tomography component is planned for observing the heat content of the circulating water masses and thus estimating also the meridional temperature transport.
Longer-term plans are loosely being considered for joining up the above tomography work in the subpolar gyre with French efforts in the Eastern Atlantic. There may be potential to fund such work under the EuroGOOS Altantic initiative.
