Role of sea surface temperature, Arctic sea ice and Siberian snow in forcing the atmospheric circulation in winter of 2012–2013
- 8.5k Downloads
During the 2012–2013 winter, the negative phase of the North Atlantic Oscillation (NAO) predominated, resulting in a cold winter over Europe and northern Asia punctuated by episodes of frigid weather. This climate anomaly is part of a recent trend towards negative values of the NAO index that has occurred over recent winters. The negative trend of the NAO may be related to atmospheric internal variability but it may also be partly forced by slowly varying components of the climate system. In the present study, we investigate the influence of surface conditions on the atmospheric circulation for the 2012–2013 winter using an atmospheric global climate model. In particular, the role of low Arctic sea ice concentration, warm tropical/North Atlantic sea surface temperature and positive Siberian snow cover anomalies are isolated by prescribing them in a set of different numerical experiments. Our simulations suggest that each of these surface forcings favored a negative NAO during the 2012–2013 winter. In our model, the combined NAO response to tropical/North Atlantic SST, Arctic sea ice and Siberian snow anomalies accounts for about 30 % of the observed NAO anomaly. Different physical mechanisms are explored to elucidate the atmospheric responses and are shown to involve both tropical and extratropical processes.
KeywordsClimate variability North Atlantic Oscillation Ocean-atmosphere interactions Arctic sea ice Siberian snow 2012–2013 winter
We thank two anonymous reviewers for comments on the manuscript. This work was supported by NSF Grant AGS-1206120. High-performance computing was performed at NCAR’s CISL.
- Abatzoglou JT, Magnusdottir G (2006) Opposing effects of reflective and non-reflective planetary wave breaking on the NAO. J Atmos Sci 63:3448–3457Google Scholar
- Collins M, Knutti R, Arblaster J, Dufresne J-L, Fichefet T, Friedlingstein P, Gao X, Gutowski WJ, Johns T, Krinner G, Shongwe M, Tebaldi C, Weaver AJ, Wehner M (2013) Long-term climate change: projections, commitments and irreversibility. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate Change 2013: The physical science basis contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change. Cambridge University Press, CambridgeGoogle Scholar
- Neale RB et al (2011) Description of the NCAR Community Atmosphere Model (CAM5). National Center for Atmospheric Research Tech. Rep. NCAR/TN-486+STR, p 268Google Scholar
- Semmler T, McGrath R, Wang S (2012) The impact of Arctic sea ice on the Arctic energy budget and on the climate of the Northern mid-latitudes. Clim Dyn (EC-Earth Special Issue). doi: 10.1007/s00382-012-1353-9
- Slingo J (2013) Why was the start to spring 2013 so cold? Metoffice, http://www.metoffice.gov.uk/media/pdf/i/2/March2013.pdf
- Waugh DW, Polvani LM (2010) Stratospheric polar vortices. In: LM Polvani, AH Sobel, DW Waugh (eds) The stratosphere: dynamics, transport and chemistry. American Geophysical Union, Washington, DCGoogle Scholar
- Xie S-P, Carton JA (2004) Tropical atlantic variability: patterns, mechanisms, and impacts. In: Wang C, Xie SP, Carton JA (eds) Earth’s climate. American Geophysical Union, Washington, DC. doi: 10.1029/147GM07