Synoptic-scale influences of snow cover and sea ice.

Abstract

Daily observational data to 30 winters (1951-80) are used to test the hypothesis that anomalous distributions of snow and ice cover influence the intensification and/or trajectories or synoptic- scale cyclones. The pools of objectively chosen cases include 100 wintertime cyclonic events in the marginal snow/ice zones of each of three regions: eastern North America, the North Atlantic Ocean and the North Pacific Ocean. The results also suggest that forecasts of weekly or monthly circulation patterns may, in situations of extreme snow/ice cover, be improved by consideration of observed snow/ice anomalies, if these anomalies persist through the forecast period. Controlled experiments with the NCAR (National Center for Atmospheric Research) primitive equations forecast model show a weaker dependence on the extent of snow and ice, although qualitative similarities to the data-based results are detectable.-from Authors