[A-CG39] Science in the Arctic Region

[ACG39-P14] Surface energy balance observed at the SIGMA-A site on the northwest Greenland ice shee

*Satoshi Hirose¹, Teruo Aoki^2,3, Masashi Niwano³, Sumito Matoba⁴, Tomonori Tanikawa³, Satoru Yamaguchi⁵, Tetsuhide Yamasaki⁶ (1.New Chitose Aviation Weather Station, Japan Meteorological Agency, 2.National Institute of Polar Research, 3.Meteorological Research Institute, Japan Meteorological Agency, 4.Institute of Low Temperature Science, Hokkaido University, 5.Snow and Ice Research Center, National Research Institute for Earth Science and Disaster Prevention, 6.Avangnaq Arctic Environmental Research Activity Project)

Keywords:Surface energy balance, Quality control, Automated weather station, Greenland Ice Sheet, albedo

The Greenland ice sheet (GrIS) has been losing snow and ice mass at an accelerating rate since the late 1990s due to surface melting and ice discharge into the surrounding ocean (Rignot et al., 2011), and there are concerns about the impact on sea level rise. In July 2012, a record surface melting event occurred across the Greenland ice sheet (Nghiem et al., 2012). In this study, we investigated the surface energy balance by using the data obtained with an automated weather station (AWS) which was installed through the SIGMA project (Aoki et al., 2014) to clarify the contributing factors to surface melting. The AWS is located at the SIGMA-A site (78°03’N, 67°38’W, 1,490 m a.s.l.) on the northwest GrIS and the study period is from 30 June 2012 to 31 December 2019. We performed quality control prior to data analysis. Our analysis showed that the amount of surface melting increased in years with warm summers, when downward sensible heat transport and net shortwave radiation increased. Positive feedback between snow grain growth and near-infrared albedo reduction played an important role in the melting process. The relationship between the North Atlantic Oscillation index and surface melt flux revealed that July 2012 was an extraordinary year, characterised by an increase in melting caused partly by increased downward longwave radiation from low-level clouds, which suppressed net longwave cooling, and partly by the increases in sensible heat flux and net shortwave radiation that are generally associated with warm summers.