The combined influences of autumnal snow and sea ice on Northern Hemisphere winters

• Published in: Geophysical research letters Vol. 43; no. 7; pp. 3478 - 3485
• Main Authors: Furtado, J. C., Cohen, J. L., Tziperman, E.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.04.2016
• Subjects: Annular Mode; Arctic regions; Arctic‐mid‐latitude teleconnections; Brackish; Climate change; Climatology; Cold season; Ice; Latitude; Marine; Mathematical models; Meteorology; Sea ice; Snow; Snow cover; Sub‐seasonal forecasting; Surface temperature; Weather; Weather forecasting; Winter; PN, Arctic
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2016GL068108

Past studies have demonstrated a significant relationship between the phase and amplitude of the Northern Annular Mode (NAM) and both Arctic sea ice and high‐latitude snow cover during boreal autumn. However, those studies have considered these forcings separately. Here we consider the collective effect of Arctic sea ice and snow cover variability for producing skillful subseasonal forecasts for Northern Hemisphere (NH) winter conditions. We find that these two cryospheric elements interact with the extratropical atmosphere differently through the cold season. Sea ice extent minima during November play a role in stratospheric and tropospheric circulation anomalies during November/December with a secondary maximum in late January/February. October snow cover anomalies, however, have impacts on the NAM primarily during middle to late winter. These timing differences are likely tied to differences in anomalous wave driving between the two cases, though other processes may be in play. We exploit these different influences to produce a skillful forecast model of subseasonal NH surface temperatures using both sea ice and snow cover as predictors, with large gains in skills in January. Overall, our study suggests that the Arctic has a demonstrable and detectable influence on midlatitude winter weather in the present and likely future climate. Key Points Considering snow cover and sea ice together creates more skillful subseasonal forecasts Sea ice and snow cover influences on winter weather share a common mechanism but differ in timing The Arctic has a detectable influence on midlatitude weather in present and likely future climates