New Perspectives on Storm Track Dynamics, Variability, and Change

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Mid-latitude storm tracks form an important part of the global circulation. Cyclones passing along the storm tracks dominate the day-to-day weather variability, and changes in storm track activity or location strongly impact regional climate variations. Baroclinic waves that make up the storm tracks are also responsible for transporting much of the heat, moisture, and momentum poleward in the midlatitudes. Thus, the understanding of storm track dynamics and variability, as well as how they may change in the future, is of great importance.Diagnostic analyses of the Coupled Model Intercomparison Project (CMIP5), simulations by multiple state-of-the-art climate models, prepared for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) will be undertaken. Two aspects of storm tracks--storm energy and cyclone frequency and strength--will be examined to provide comprehensive new perspectives of storm track dynamics, variability and change. Storm tracks simulated by state-of-the-art climate models will be compared to those derived from reanalysis data to document model biases, and differences in storm track variability and change among the different climate models. Making use of the unprecedented quality and diversity of model simulations, the relationship between cyclone frequency and strength and mean flow variability will be examined. Results of these studies will provide insights on the physical processes that lurk behind model biases and differences, and furnish new ideas regarding how these biases and differences might impact model projections.