Canadian Node:The node is located at Dalhousie University and is the Central node in the Network. Its researchers will collaborate closely with researchers from Environment Canada (the government organization in Canada responsible for weather forecasting and climate change projections). The research to be carried out at the Central node has two main themes.
Short Term Forecasting of Extremes: The practical goal is to extend the range of accurate forecasts (hours to weeks) of extreme atmosphere, ocean and sea ice conditions using coupled atmosphere-ocean-ice models. The space scales of interest in both ocean and atmosphere will range from tens of kilometers to global. The atmospheric and ocean models will be global in extent but will have the capability of higher horizontal resolution in areas of particular interest. An important focus will be the prediction of strong mid-latitude storms (e.g., atmospheric “bombs”) in the North Atlantic and associated changes in extreme sea levels, currents, sea ice distributions and iceberg trajectories (a threat to offshore oil and gas activities). The modeling will focus initially on case studies corresponding to observed extreme events. In the first stages of the research, the forecast wind fields will be used to drive wave models “off-line”; in years 4 and 5 a wave model will be two-way coupled to the atmosphere-ocean-ice model.
Particular attention will be paid to the validation of the model forecasts (i.e., testing the accuracy of the forecasts of extreme events) and also model improvement. An important scientific focus will be extending the range of useful forecasts, e.g., through modes of atmospheric variability like the Madden Julian Oscillation (periods of 30 to 90 days). If such atmospheric modes of variability can be correctly simulated by the coupled model, they may increase significantly the range of accurate forecast of atmospheric, and possibly ocean, extremes. Another important characteristic of the coupled modeling will be ensemble prediction (making multiple predictions each time, with slight variations resulting from uncertainty in initial conditions). This will allow the probability distribution of future states to be estimated rather than a single deterministic forecast.
Impact of Climate Change on the Probability Distribution of Extremes: Following the above development and validation of the coupled atmosphere-ocean-ice model for the extreme case studies, the same model will be used in years 4 and 5 to assess the impact of climate change on extremes. One approach will be to rerun the case studies with large-scale initial conditions (and boundary conditions for nested regional submodels) that reflect the most accurate climate change projections presently available. The initial and boundary conditions will be varied to reflect the uncertainty in the climate change projections. (These will come from the suite of model runs presently being prepared for the next IPCC Assessment.) In this way, it will be possible to assess the impact of climate change on the evolution of the extreme events, and thus assess the impact of climate change on the tails of probability distributions of wind, coastal sea, current and waves.