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Arctic Synoptic Activity Associated with Sea Ice Variability Using Self-Organizing Maps
- Event Type
- Department of Atmospheric Sciences, University of Illinois
- Room 114 of the Transportation Building
- Nov 20, 2013 3:00 pm
- Catrin Mills, Graduate Student, DAS, University of Illinois
Arctic synoptic activity is objectively characterized using self-organizing maps (SOMs) to categorize observed weather patterns over the 1979-2010 period. The European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-interim dataset) provides the daily sea level pressures from which the SOMs are computed. Time series of frequencies and durations of synoptic weather patterns are correlated with two sea ice metrics, Fram Strait outflow and year-to-year changes in September sea ice extent. Beaufort High synoptic patterns are increasing in frequency in spring and summer and their spring frequencies are associated with ice loss. Some synoptic patterns correlate more highly to sea ice metrics than do time series of the Arctic Oscillation (AO) or the North Atlantic Oscillation (NAO). Synoptic activity in the present-day and 21st Century Community Climate System Model Version 4 (CCSM4) is also characterized and compared to the re-analysis SOM analysis. Overall, present-day CCSM4 appears to have a negative SLP bias, over-simulating strong Icelandic Low patterns that penetrate far north into the central Arctic and under-simulating strong ridge patterns over the Central Arctic. Twenty-first CCSM4 shows a deepening of low pressure patterns over the Arctic.