92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Thursday, 26 January 2012: 2:00 PM
Physical Mechanisms of the European Snow Cover Long-Term Variation
Room 355 (New Orleans Convention Center )
Yoojin Kim, Seoul National University, Seoul, South Korea; and K. Y. Kim and B. M. Kim

The snow cover extent has been reduced in northern Hemisphere due to global warming in recent years. The regional-scale changes in snow cover during winter, however, have somewhat different appearances from the global change. Satellite observation of winter snow cover in Europe is analyzed to investigate the long-term variation of snow cover. For this study, sixteen-week winter data for 37 years from December 1973 to March 2010 are used. Cyclostationary EOF (CSEOF) technique is used to understand the variations of snow cover extent. The first three CSEOF modes, the first being the seasonal cycle and the others sub-seasonal variations, are interpreted in the present study. The third mode shows a positive trend of snow cover in December and January since the 2000's. Based on the regression method in CSEOF space, physically related evolution patterns of atmospheric variables are derived from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. To understand the condition of the Atlantic Ocean, NOAA Optimum Interpolation Sea Surface Temperature (OISST) v.2 data set is also analyzed. Colder (Warmer) winter temperature are associated with an expansion (reduction) of snow cover in Europe region. Colder (Warmer) temperature is induced by weaker (stronger) westerlies, which blow from the Atlantic Ocean. Prevailing climate teleconnection pattern is also related with snow cover extent; negative (positive) phase of North Atlantic Oscillation (NAO), a dominant climate pattern in Europe, seems germane to snow cover expansion (reduction) from January to February.

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