Northern Hemisphere snow cover and atmospheric blocking variability



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García Herrera, Ricardo and Barriopedro Cepero, David (2006) Northern Hemisphere snow cover and atmospheric blocking variability. Journal of Geophysical Research-Atmospheres, 111 (D21). ISSN 0148-0227

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The interseasonal relationship between Northern Hemisphere (NH) snow cover and regional blocking patterns is explored for a 31-year data set. It is found that snow cover exerts an important influence on regional atmospheric blocking, which, in turn, modulates snow cover extent at subcontinental scales. Observational results provide strong evidence of two primary linkages in the seasonal snow cover-blocking relationship that support an interannual persistence cycle: The first one links winter blocking over the Atlantic and the subsequent spring (summer) Eurasian (North American) snow cover anomalies; the second one implies that spring (summer) Eurasian (North American) snow cover precedes an anomalous winter Atlantic blocking activity. We describe the temporal stages of the snow cover-blocking relationship in the framework of a six-step conceptual model. According to that, an enhanced Atlantic blocking activity in winter favors a later spring snow disappearance through an enhanced cold advection toward western Eurasia. The resulting snow cover anomalies partially force an opposite-sign blocking response over west and central Pacific which is sustained through spring and early summer, presumably because of the persistence of snow cover anomalies. This anomalous pattern seems to play a role in the propagation of snow cover anomalies from Eurasia in spring to the Hudson’s Bay region of North America in summer. The excessive snow cover over this region induces an asymmetrical temperature distribution, which, in turn, favors blocking activity over Europe and the West Pacific. The connection between autumn and winter climates is not clear but it could be related with the ability of autumn high ATL blocking activity to determine an early snow cover appearance in October over western Eurasia. This linkage completes a snow cover-blocking cycle of interactions which identifies snow cover as a candidate for the recently observed blocking trends and a contributor to the interannual persistence of winter climate.

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© 2006 by the American Geophysical Union. The authors wish to thank Rutgers University for providing the snow cover data. We would also like to thank to three anonymous reviewers for their valuable comments. Ricardo Trigo and Roxana Bojariu contributed to improve this manuscript. The Spanish Science and Technology Department supported this study trough the VALIMOD (Climatic VALIdation of Conceptual MODels) project (REN2002-04558-C04-01).

Uncontrolled Keywords:Indian Monsoon Rainfall, Atlantic Oscillation, Interannual Variability, Weather Regimes, Climate, Impact, Nao, Temperature, Circulation, Extent
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:24695
Deposited On:19 Mar 2014 10:23
Last Modified:10 Dec 2018 15:05

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