Exploring Factors Influencing Arctic Melt Ponds
ARM data show that warm air incursions play an important role in the development of Arctic melt ponds.
The Arctic is warming faster than many areas around the globe. One reason for this is because earlier melt of sea ice results in heating from greater sunlight absorption. Melt ponds, pools of meltwater on the ice surface, are important in darkening the ice. This study seeks to understand what causes ponds to start forming, using data from the past 18 years at the Atmospheric Radiation Measurement (ARM) site in Utqiagvik (formerly Barrow), Alaska and a three-dimensional sea ice model with resolved melt ponds.
The study finds that warm, moist air blowing in from the south may play a large role in the formation of melt ponds. The model shows that sunlight is the source of most of the energy but that pond formation is prevented by cooling from cold air passing over the surface and from infrared radiation loss to space. When the warming exceeds the loss of surface heat, ponds form. The study determined that reduction in and/or reversal of cooling by the air is more important in controlling melting than infrared radiation loss to space at this coastal study site. Changes in the timing and frequency of spring warm air incursions may have significant implications on the ice cover and provide predictive power for seasonal ice retreat.
Melt ponds on summer Arctic sea ice control surface albedo, governing energy and mass balance of the ice. The date ponds first form has been connected to interannual variations in ice retreat. This study evaluates the surface energy balance that governs this critical pond formation date. A three-dimensional sea ice model with resolved melt ponds is used to diagnose pond onset date at a coastal site across years with observed surface fluxes but incomplete pond observations. Results show that the combined sensible and latent heat flux is the best predictor of pond formation date. This finding supports the hypothesis that synoptic weather events transporting warm, moist air into the Arctic are key to initiating pond formation, triggering albedo feedbacks, and, by extension, ice retreat.
Oregon State University
This research was supported by the National Science Foundation, grant ARC-1418064. Surface energy flux data were obtained from the Atmospheric Radiation Measurement (ARM) user facility, a U.S. Department of Energy (DOE) Office of Science user facility managed by The Office of Biological and Environmental Research (https:// doi.org/10.5439/1027372). We would like to acknowledge high-performance computing support from Cheyenne (doi:10.5065/D6RX99HX) provided by NCAR’s Computational and Information Systems Laboratory, sponsored by the National Science Foundation.
Skyllingstad, E. D., and C. Polashenski. “Estimated heat budget during summer melt of Arctic first-year sea ice.” Geophysical Research Letters 45(21), 11,789-11,797 (2018). DOI:10.1029/2018GL080349