Abstract
Two high melt episodes occurred on the Greenland ice sheet in July 2012, during which nearly the entire ice sheet surface experienced melting. Observations from an automatic weather station (AWS) in the lower ablation area in South Greenland reveal the largest daily melt rates (up to 28 cm d-1 ice equivalent) ever recorded on the ice sheet. The two melt episodes lasted 6 days, equivalent to 6% of the June-August melt period, but contributed 14 % to the total annual ablation of 8.5 m ice equivalent. We employ a surface energy balance model driven by AWS data to quantify the relative importance of the energy budget components contributing to melt through the melt season. During the days with largest daily melt rates, surface turbulent heat input peaked at 552 Wm-2, 77 % of the surface melt energy, which is otherwise typically dominated by absorbed solar radiation. We find that rain contributed ca. 7 % to melt during these episodes.
Highlights
Understanding the response of the Greenland Ice Sheet (GrIS) to contemporary climate change is crucial to predicting future changes in global sea-level (IPCC, 2013; Dutton et al, 2015)
We present observed daily ice melt rates from the 2012 summer (June, July, August), and perform diagnostic simulations of daily melt rates using a surface energy balance (SEB) model driven by automatic weather station (AWS) data, allowing us to quantify and rank all melt energy sources through the melt season
The two high melt episodes are characterized by relatively high air temperatures, wind speed and downward longwave radiation (LRin), while downward shortwave radiation (SRin) is relatively low
Summary
Understanding the response of the Greenland Ice Sheet (GrIS) to contemporary climate change is crucial to predicting future changes in global sea-level (IPCC, 2013; Dutton et al, 2015). Year 2012 established a new surface melt extent record, when satellite observations revealed that melting occurred across virtually the entire ice sheet surface on 12 July 2012. This extraordinary melt episode (8–11 July), unprecedented in the satellite record, was due to an advective heatwave over most of Greenland (Nghiem et al, 2012; Tedesco et al, 2013; Neff et al, 2014; Fausto et al, 2016). A second high melt episode occurred 27–28 July, covering all of West Greenland (Fausto et al, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
