Contribution of late spring Eurasian snow cover extent to Canadian winter temperatures

摘要

This study examines intercontinental linkages between late spring and early summer Eurasian snow cover extent (SCE _(ss)) anomalies and the following winter temperature anomalies over Canada for the 1972-2006 period. The structure of the second interannual mode of Canadian winter temperatures variability captures the SCE _(ss) related modulation. The North Atlantic winter atmospheric circulation changes associated with the SCE _(ss), resembling the negative phase of the North Atlantic Oscillation (NAO), suggest a possible pathway for the SCE _(ss)influences on the Canadian winter temperatures. Regression and composite analyses show that the SCE _(ss) relate robustly to the Canadian winter climate. Larger-than-normal SCE _(ss) is associated with below normal winter temperatures in south-central Canada and above normal temperatures over northeastern Canada. Predictive skill of Canadian winter temperatures based on a cross-validated regression model shows that the SCE _(ss) offers the predictive potential over regions of Canada where El Ni?o-Southern Oscillation (ENSO) related skill is weak or nonexistent. Analysis of winter extreme minimum temperatures, by a non-stationary generalized extreme value model, with the SCE _(ss) as a covariate, exhibits statistically significant changes over Canada resembling a pattern similar to that of winter mean temperatures. Wavelet analysis shows significant coherence between the SCE _(ss) and the second mode of winter temperature variability in the 8-12-year band.