Seasonal variations of Arctic cloud in recent 14 years using CALIPSO-GOCCP

Abstract

This study documents the three-dimensional structure and long-term trend of Arctic cloud cover with 14-year Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations from a seasonal perspective. Results show that Arctic Ocean presents larger low-level cloudiness and more evident vertical contrast between low and high-level cloud cover than Arctic land. Furthermore, Arctic Atlantic experiences the largest total and low-level cloud cover all year long, with relatively weak seasonal variation. In contrast, the low-level cloud cover over Arctic Pacific displays a pronounced bimodal annual cycle, as well as the low-level cloud cover over Arctic land. Arctic Atlantic with the maximum cloud fraction has the highest altitude of about 1.2 km above open sea in winter, which is near the surface in summer. The cloudiness in the lower troposphere over open water is significantly larger than that over ice except in winter, whereas, the liquid-containing cloud over open water is significantly larger than that over ice in the lower troposphere in four seasons. Moreover, though the liquid-containing cloud dominates the low-level cloud cover, its increasing trend is driven by liquid-containing and ice-containing cloud together. Instead, the ice-containing cloud dominates the high-level cloud cover and its increasing trend in all seasons over most Arctic regions, except a negative trend over Greenland in winter. Our work presents a more comprehensive picture of the Arctic cloud cover, which provides an insight into understanding of Arctic cloud and Arctic climate system.