Warm-air advection, air mass transformation and fog causes rapid ice melt

• Published in: Geophysical research letters 2015-07, Vol.42 (13), p.5594-5602
• Main Authors: Tjernström, Michael, Shupe, Matthew D., Brooks, Ian M., Persson, P. Ola G., Prytherch, John, Salisbury, Dominic J., Sedlar, Joseph, Achtert, Peggy, Brooks, Barbara J., Johnston, Paul E., Sotiropoulou, Georgia, Wolfe, Dan
• Format: Article
• Language: English
• Subjects: Advection; Aerodynamics; Air masses; Air temperature; Arctic; Area; atmosfärvetenskap och oceanografi; Atmosphere; Atmospheric Sciences and Oceanography; Energy; Energy flux; Energy transfer; Fluctuations; Fluid dynamics; Fog; Heat; Heat flux; Heat transfer; Ice formation; Ice melting; Long wave radiation; Marine; Melting; Melts; Radiation; Satellite imagery; Satellites; Sea ice; Sea ice concentrations; sea-ice melt; Solar radiation; Surface energy; surface energy balance; surface inversion; Surface properties; Surface temperature; Temperature; Temperature effects; Temperature inversion; Temperature inversions; Transformations; Turbulence; Turbulent heat flux; warm-air advection
• ISSN: 0094-8276; 1944-8007; 1944-8007
• DOI: 10.1002/2015GL064373

Direct observations during intense warm‐air advection over the East Siberian Sea reveal a period of rapid sea‐ice melt. A semistationary, high‐pressure system north of the Bering Strait forced northward advection of warm, moist air from the continent. Air‐mass transformation over melting sea ice formed a strong, surface‐based temperature inversion in which dense fog formed. This induced a positive net longwave radiation at the surface while reducing net solar radiation only marginally; the inversion also resulted in downward turbulent heat flux. The sum of these processes enhanced the surface energy flux by an average of ~15 W m−2 for a week. Satellite images before and after the episode show sea‐ice concentrations decreasing from > 90% to ~50% over a large area affected by the air‐mass transformation. We argue that this rapid melt was triggered by the increased heat flux from the atmosphere due to the warm‐air advection. Key Points The importance of both large‐scale dynamics and local feedback for sea‐ice melt The location of extra melt near the ice edge, due to the air‐mass transformation The role of clouds, longwave radiation and turbulent heat flux for sea‐ice melt