Cloud cover over Spitsbergen and its relation to atmospheric circulation (1983-2015)

This paper discusses the cloud cover and its relation to atmospheric circulation over Spitsbergen during 1983-2015. It focuses on monthly and seasonal cloud covers and on the frequency of days with specific cloud cover (cloudless, clear, cloudy and completely overcast sky) and their relation to various circulation types. In the research period the cloud cover characteristics were differentiated over the island on both monthly and seasonal scales, and they strongly depended on the direction of air advection. The highest mean daily cloud cover was reported for circulation types with air advection from the south (S+SWc and S+SWa). The greatest variation in the cloud cover distribution was observed during the polar night (at Svalbard Lufthavn and Ny-Ålesund) or in the autumn (Hornsund). The long-term variability in the cloud cover significantly depends on the frequency of N+NEa type (negative correlation) and on S+SWc and W+NWc and Cc+Bc types (positive correlation), particularly in spring