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Relationship Between Wintertime Leads and Low Clouds in the Pan‐Arctic
Author(s) -
Li Xia,
Krueger Steven K.,
Strong Courtenay,
Mace Gerald G.
Publication year - 2020
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2020jd032595
Subject(s) - environmental science , arctic , cloud cover , climatology , atmospheric sciences , cloud fraction , boundary layer , longwave , downwelling , cloud top , lead (geology) , context (archaeology) , satellite , meteorology , cloud computing , radiative transfer , geography , geology , oceanography , upwelling , physics , archaeology , quantum mechanics , astronomy , geomorphology , computer science , thermodynamics , operating system
Wintertime leads play an important role in the Arctic boundary layer as they promote turbulent flux exchanges from the warm exposed water to the cold atmosphere, thereby affecting the boundary layer cloudiness and structure. Recent work suggests that less (more) low‐level cloud occurrence is found in higher (lower) lead fraction periods, yet the analysis efforts were limited to a peripheral sea north of Barrow, Alaska. Here, we extend the previous study to examine this relationship between wintertime Arctic leads and low clouds in the context of a longer time series (November–March, 2006–2011) and greater spatial coverage (pan‐Arctic), based on cloud products from CloudSat and Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellites and lead area fraction derived from Advanced Microwave Scanning Radiometer for EOS (AMSR‐E) observations. We focus on the east side of high‐pressure systems to isolate lead impacts on boundary layer clouds. Using a k ‐means cluster‐analysis algorithm, low‐level cloud regimes are categorized on the basis of occurrence frequency of low‐level clouds. We find that, in the pan‐Arctic, less (more) low‐level cloud occurrence is associated with higher (lower) large‐scale lead flux, in agreement with the previous study. This lead‐low cloud association exhibits strong regional variation; it is enhanced over the Beaufort Sea where the variability of large‐scale meteorological conditions is decreased. These results suggest that a higher lead fraction might have important impacts on the Arctic surface energy budget by decreasing downwelling longwave radiation through reduced low‐level cloudiness.