Deconstructing the climate change response of the Northern Hemisphere wintertime storm tracks

• Published in: Climate dynamics Vol. 45; no. 9-10; pp. 2847 - 2860
• Main Authors: Harvey, B. J., Shaffrey, L. C., Woollings, T. J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2015; Springer; Springer Nature B.V
• Subjects: Climate change; Climatic changes; Climatology; Cyclones; Earth and Environmental Science; Earth Sciences; Environmental aspects; Geophysics/Geodesy; Meteorology; Oceanography; Storms; Winter; Polar amplification; Climate change; Drivers of change; CMIP3; Storm tracks
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-015-2510-8

There are large uncertainties in the circulation response of the atmosphere to climate change. One manifestation of this is the substantial spread in projections for the extratropical storm tracks made by different state-of-the-art climate models. In this study we perform a series of sensitivity experiments, with the atmosphere component of a single climate model, in order to identify the causes of the differences between storm track responses in different models. In particular, the Northern Hemisphere wintertime storm tracks in the CMIP3 multi-model ensemble are considered. A number of potential physical drivers of storm track change are identified and their influence on the storm tracks is assessed. The experimental design aims to perturb the different physical drivers independently, by magnitudes representative of the range of values present in the CMIP3 model runs, and this is achieved via perturbations to the sea surface temperature and the sea-ice concentration forcing fields. We ask the question: can the spread of projections for the extratropical storm tracks present in the CMIP3 models be accounted for in a simple way by any of the identified drivers? The results suggest that, whilst the changes in the upper-tropospheric equator-to-pole temperature difference have an influence on the storm track response to climate change, the large spread of projections for the extratropical storm track present in the northern North Atlantic in particular is more strongly associated with changes in the lower-tropospheric equator-to-pole temperature difference.