Atmospheric Conditions during the Arctic Clouds in Summer Experiment (ACSE): Contrasting Open Water and Sea Ice Surfaces during Melt and Freeze-Up Seasons

• Published in: Journal of climate 2016-12, Vol.29 (24), p.8721-8744
• Main Authors: Sotiropoulou, Georgia, Tjernström, Michael, Sedlar, Joseph, Achtert, Peggy, Brooks, Barbara J., Brooks, Ian M., Persson, P. Ola G., Prytherch, John, Salisbury, Dominic J., Shupe, Matthew D., Johnston, Paul E., Wolfe, Dan
• Format: Article
• Language: English
• Subjects: Arctic; atmosfärvetenskap och oceanografi; Atmosphere-ocean interaction; Atmospheric Sciences and Oceanography; Boundary layer; Clouds; Fluxes; Inversions; Marine
• ISSN: 0894-8755; 1520-0442; 1520-0442
• DOI: 10.1175/JCLI-D-16-0211.1

The Arctic Clouds in Summer Experiment (ACSE) was conducted during summer and early autumn 2014, providing a detailed view of the seasonal transition from ice melt into freeze-up. Measurements were taken over both ice-free and ice-covered surfaces near the ice edge, offering insight into the role of the surface state in shaping the atmospheric conditions. The initiation of the autumn freeze-up was related to a change in air mass, rather than to changes in solar radiation alone; the lower atmosphere cooled abruptly, leading to a surface heat loss. During melt season, strong surface inversions persisted over the ice, while elevated inversions were more frequent over open water. These differences disappeared during autumn freeze-up, when elevated inversions persisted over both ice-free and ice-covered conditions. These results are in contrast to previous studies that found awell-mixed boundary layer persisting in summer and an increased frequency of surface-based inversions in autumn, suggesting that knowledge derived from measurements taken within the pan-Arctic area and on the central ice pack does not necessarily apply closer to the ice edge. This study offers an insight into the atmospheric processes that occur during a crucial period of the year; understanding and accurately modeling these processes is essential for the improvement of ice-extent predictions and future Arctic climate projections.