THOR stands for "Thermohaline Overturning – at Risk?" and is an EU-funded FP7 project that will establish an operational system to monitor and forecast the development of the North Atlantic Thermohaline Circulation (THC) on decadal time scales and to assess its stability and the risk of a breakdown in a changing climate.
ECMWF is involved in research on the predictability of the THC. The last decade has seen substantial developments in coupled ocean-atmosphere models, in global data assimilation systems for the ocean and the atmosphere, and in ocean observing systems. With these data assimilation systems, retrospective global analyses of the ocean and atmosphere state have been made over the past 40 years, and from these climate predictability on seasonal time scales has been assessed using state-of-the-art coupled models, see e.g. the ENSEMBLES project. These developments suggest that the time is now ripe to assess decadal predictability using similar techniques, ie from ensembles of state-of-the-art coupled model integrations, initialised using realistic ocean-atmosphere analyses. Since the THC is one of the key physical processes for which there is evidence of decadal predictability, a focus on the THC is relevant for a first phase of this type of assessment of decadal predictability.
The project was officially launched in December 2008 under the cooperation of 20 research institutions in 9 European countries and will run for 4 years. The overall activities of the project are coordinated by the Institute of Oceanography at the University of Hamburg.
For further information about the project, please check the THOR website or contact Antje Weisheimer.