Seasonal co-variability of surface downwelling longwave radiation for the 1982-2009 period in the Arctic

The decreasing of the sea ice cover observed in the Arctic represent a strong indicator of the ongoing climate change. Several physical processes are contributing to this one. The study of the co-variability of sea ice concentration (SIC) with other physical parameters may be useful to a better understanding of the strength and nature of the Arctic sea ice decline. This work concerns the investigation of the mutual variability between the seasonal fields of SIC and the downwelling surface shortwave radiation (SIS) in clear sky conditions, for the 1982-2009 period. SIC and SIS monthly data were collected from the National Snow and Ice Data Center (NSDIC) and from the Satellite Application Facility on Climate Monitoring (SAFCM), respectively. Then mainly analyzed through the method of maximum covariance analysis (MCA). Interesting results were found during the summer season, which is the relevant season since the sea ice melting: regions of maximum co-variability are located close to the Barents Sea and the Kara Sea. In addition, in these areas, expansion coefficients time series (of principal modes), show statistically significant (at 95%) correlations with climate oscillations such as the Northern Annular Mode (NAM), the North Atlantic Oscillation (NAO) and the Pacific North America (PNA) pattern.