PREDICATE Science

The two goals of this 3-year research programme are (a) to improve understanding of the processes responsible for decadal-timescale fluctuations in the climate of the Atlantic-European region, and (b) to assess the extent to which such fluctuations are predictable. The proposal has been developed in response to the needs of the European Union described in the Energy, environment and sustainable development thematic programme of Framework 5.

European climate exhibits substantial fluctuations on decadal timescales. The North Atlantic Oscillation (NAO) index, which is the most important single index of climate fluctuations in the Atlantic-European sector, has undergone major low frequency fluctuations during the last century, with high values predominating at the beginning and end of the century and low values in the 1950s-1970s. These fluctuations were associated with large anomalies (up to 60% of the mean) in storminess, temperature and rainfall, resulting in major impacts on the peoples and economies of Europe.

Current understanding of the causes of decadal fluctuations in climate is limited. One factor is changes in external forcings of the atmosphere, such as increasing levels of greenhouse gases and variations in solar forcing. Another factor is internal fluctuations within the climate system. For example, interactions between the oceans and the atmosphere are known to be a major cause of climate fluctuations on interannual timescales and may also be the dominant cause of fluctuations on decadal timescales. Progress in understanding how ocean-atmosphere interactions influence decadal fluctuations in climate is urgently needed to improve the detection and attribution of anthropogenic climate change.

Fluctuations in climate are sometimes predictable. In particular, scientists have made progress in developing systems to forecast interannual fluctuations such as El Nino. As reliability improves, these forecasts will be of enormous value to governments, businesses and individuals. Forecasting decadal fluctuations in climate is at a much earlier stage of development. The priority at this time is to establish what level of decadal-timescale predictability exists.
In response to the need for both progress in understanding and assessment of predictability, this project has five objectives:

To establish the skill with which decadal fluctuations in the North Atlantic Oscillation (NAO) observed during the twentieth century can be simulated in state-of-the-art atmosphere General Circulation Models (GCMs) forced with observed sea surface temperatures, and to quantify the potential predictability of the NAO. To establish how skill varies between different models, and which aspects of the observed sea surface temperature fluctuations are most important for forcing the NAO.
To establish the skill with which decadal fluctuations in the Atlantic Ocean during the second half of the twentieth century can be simulated in state-of-the-art ocean GCMs forced with observed surface winds. To establish how skill varies between different models, and what resolution is required to simulate the observed fluctuations.
To assess by detailed comparison with the latest observational datasets the extent to which the mechanisms responsible for decadal climate fluctuations in state-of-the-art coupled GCMs are realistic. To assess the role of tropical-extratropical connections in the ocean and atmosphere in decadal climate fluctuations
To provide a quantitative assessment of the importance of ocean-atmosphere interactions for decadal fluctuations in Atlantic-European climate.
To improve the European capability for forecasting decadal fluctuations in Atlantic-European climate, and to assess the predictability of such fluctuations.

The objectives will be achieved by a partnership between eight centres of excellence in the numerical modelling of climate. The eight principal contractors are located in six different European countries and will carry out research using 11 different atmosphere, ocean and coupled GCMs. The work programme consists of a coordinated programme of model experimentation and analysis. The experiments are designed in such a way that results from different models can be compared very carefully. These comparisons will greatly assist understanding, and will form the basis of joint publications. The variety of models will ensure that results are not model-specific. The benefits of this sort of coordinated programme of model experimentation and analysis have been made plain by the success of projects such as the Atmospheric Model Intercomparison Project (AMIP), and the Framework 4 PROVOST and SHIVA projects.

PREDICATE involves four workpackages:

WP1: Mechanisms and Predictaility of Decadal Fluctuations in the Atmosphere.

WP2: Mechanisms of Decadal Fluctuations in the Atlantic Ocean

WP3: Decadal Climate Prediction for the Atlantic European Region.

WP4: Project Management, Interactions with Users and Dissemination of Results.

PREDICATE Organisational Chart