The role of air-sea coupling in Atlantic storm track change (Invited Presentation)

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Wednesday, 7 January 2015: 10:30 AM
224A (Phoenix Convention Center - West and North Buildings)
Tim Woollings, University of Oxford, Oxford, United Kingdom

Storm tracks in general are expected to shift polewards in response to climate change, but a notable exception is the wintertime North Atlantic storm track. In this case the response is characterised by a strengthening and extension of the storm track into Europe, albeit with a large spread between different climate models.

We suggest that this distinct storm track response arises due to the strong ocean-atmosphere coupling in the North Atlantic, in particular associated with the weakening of the Atlantic Meridional Overturning Circulation (AMOC). Evidence for this is presented by comparing different climate models, including several with slab instead of dynamic oceans, and the response to a forced shutdown of the AMOC in climate models.

Experiments are then presented with an atmosphere-only model forced by SST and sea ice patterns designed to span the model spread in the response to climate change. These experiments highlight the importance of the high latitudes and the response of sea ice as a source of uncertainty in future storm track change.