The Decrease of Snow Occurrence Under Future Warming over the Eastern United States

Tuesday, 16 December 2014
Liang Ning and Raymond S Bradley, University of Massachusetts Amherst, Amherst, MA, United States
We investigate the risk of losing snow across the eastern United States under future warming for the late 21st century by applying both observed and downscaled high-resolution (~12.5 km) daily temperature and precipitation to an empirical hyperbolic tangent function to calculate the historical and future snow occurrence. The observed distributions of snow frequency show that snow-rain transition zones are mainly zonally distributed since they are determined by temperature, with a slight shift to the south over the Appalachian Mountain region. The snow-rain transition zone is located around 40ºN for winter months (DJF), 43ºN for March, and 45ºN for November. These observed patterns can be reproduced by the historical multi-GCM ensemble average. The future projection shows that the snow-rain transition zone will shift to the north under the background of warming at magnitudes of 2-6ºC over this region, indicating that large areas will have reduced snow occurrence in the future. The northward shifts are about 2º latitude under the RCP4.5 scenario and 4º latitude under the RCP8.5 scenario. The percentage area losing snow occurrence is also assessed.