1. Sea Surface Temperature, 4 - 9 November 2002

3. Nomenclature Meridional Overturning Circulation (MOC): Total northward/southward flow, over latitude and depth Thermohaline Circulation (THC): Part of MOC driven by heat & water exchange with atmosphere MOC is observable quantity; THC an interpretation Often used synonymously, but wind-driven MOC part must be considered separately

4. Meridional Overturning Circulation (MOC) Jayne & M 2001

6. CO 2 -induced THC slowdown? Possibly leading to cooling? Current observations do not allow us to identify which model’s projection is correct (if any) MOC estimated through ship-based sections across ocean, usually >10 years apart Need continuous observation of MOC Cannot base strategy on repeat sections (not enough people or money)

7. Approach: Integrated thermal wind (geostrophy) Ekman contribution to MOC included Surface layer Ekman transport assumed to return independent of depth (Jayne & M ‘01)

8. MOC, Jan. - July Jayne & M 2001 “Ekman reconstruction” Jan. - July

9. 26.5°N MOC Monitoring Project PIs: Jochem Marotzke, Stuart Cunningham, Harry Bryden (SOC) Funded by NERC RAPID with £4.0M over 5 years Will support 2 Post-docs, 1 Research Assistant, Started 1 April 2003 Expected first instrument deployment: January 2004

10. Why 26.5°N? Near Atlantic heat transport maximum – captures total heat transport convergence into North Atlantic South of area of intense heat loss from ocean to atmosphere over Gulf Stream extension MOC dominates heat transport (Hall & Bryden ‘82) Heat transport variability dominated by velocity fluctuations (Jayne & Marotzke, 2001) Florida Strait transport monitored for >20 years (now: Johns, Baringer & Beal, Miami, collaborators) 4 modern hydrographic occupations

11. The Future: Deployment of instruments likely to start Jan 2004 4 full years of measurements during RAPID Deliverable: Demonstration of how MOC can be monitored effectively and efficiently Measurements must continue beyond lifetime of RAPID, as part of an early warning system