Summertime low clouds mediate the impact of the large-scale circulation on Arctic sea ice

• Published in: Communications Earth & Environment
• Main Authors: Huang, Yiyi, Ding, Qinghua, Dong, Xiquan, Xi, Baike, Baxter, Ian
• Other Authors: National Aeronautics and Space Administration, NSF | Directorate for Geosciences, United States Department of Commerce | NOAA | Climate Program Office
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: General Earth and Planetary Sciences; General Environmental Science; Arctic; albedo; Sea ice
• Online Access: http://dx.doi.org/10.1038/s43247-021-00114-w; http://www.nature.com/articles/s43247-021-00114-w.pdf; http://www.nature.com/articles/s43247-021-00114-w

Abstract The rapid Arctic sea ice retreat in the early 21 st century is believed to be driven by several dynamic and thermodynamic feedbacks, such as ice-albedo feedback and water vapor feedback. However, the role of clouds in these feedbacks remains unclear since the causality between clouds and these processes is complex. Here, we use NASA CERES satellite products and NCAR CESM model simulations to suggest that summertime low clouds have played an important role in driving sea ice melt by amplifying the adiabatic warming induced by a stronger anticyclonic circulation aloft. The upper-level high pressure regulates low clouds through stronger downward motion and increasing lower troposphere relative humidity. The increased low clouds favor more sea ice melt via emitting stronger longwave radiation. Then decreased surface albedo triggers a positive ice-albedo feedback, which further enhances sea ice melt. Considering the importance of summertime low clouds, accurate simulation of this process is a prerequisite for climate models to produce reliable future projections of Arctic sea ice.