Spatial and temporal variations in monthly averaged cloud cover based on AVHHR Polar Pathfinder data

Cloud cover strongly influences the Arctic energy balance by reflecting shortwave radiation to space and emitting longwave radiation to the surface. Spatial and temporal variations in Arctic cloud cover could therefore directly influence snow and ice conditions by controlling the surface energy balance. Variations in cloud cover could also indirectly affect surface conditions through the temperature-albedo feedback mechanism. The objective of this paper is therefore to examine spatial and temporal patterns in monthly averaged Arctic cloud cover amounts from 1982-1998, based on Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder data. Results indicate cloud cover amounts are highest during late spring and early summer and lowest during early winter and early spring, consistent with previous cloud climatology analyses. Superimposed upon the large monthly variations are significant trends towards increased cloud cover in several regions, progressing eastward from Siberia to the Beaufort Sea to the Canadian Arctic Archipelago, from early spring through summer. Regression analyses indicate that the cloud cover variations are significantly correlated with variations in monthly averaged Arctic Oscillation (AO) values, and that they are consistent with the observed trends in Arctic atmospheric pressure and synoptic patterns.