Knowledge Resource Center for Ecological Environment in Arid Area
| Climatology and firn processes in the lower accumulation area of the Greenland ice sheet | |
| Charalampidis;Charalampos | |
| 出版年 | 2016 |
| 学位授予单位 | Uppsala universitet, Luft-, vatten och landskapslära, Geological Survey of Denmark and Greenland (GEUS), Uppsala |
| 英文摘要 | The Greenland ice sheet is the largest Northern Hemisphere store of fresh water, and it is responding rapidly to the warming climate. In situ observations document the changing ice sheet properties in the lower accumulation area, Southwest Greenland. Firn densities from 1840 meters above sea level retrieved in May 2012 revealed the existence of a 5.5-meter-thick, near-surface ice layer in response to the recent increased melt and refreezing in firn. As a consequence, vertical meltwater percolation in the extreme summer 2012 was inefficient, resulting in surface runoff. Meltwater percolated and refroze at six meters depth only after the end of the melt season. This prolonged autumn refreezing under the newly accumulated snowpack resulted in unprecedented firn warming with temperature at ten meters depth increased by more than four degrees Celsius. Simulations confirm that meltwater reached nine meters depth at most. The refrozen meltwater was estimated at 0.23 meters water equivalent, amounting to 25 % of the total 2012 ablation. A surface energy balance model was used to evaluate the seasonal and interannual variability of all surface energy fluxes at that elevation in the years 2009 to 2013. Due to the meltwater presence at the surface in 2012, the summer-averaged albedo was significantly reduced (0.71 in 2012; typically 0.78). A sensitivity analysis revealed that 71 % of the subsequent additional solar radiation in 2012 was used for melt, corresponding to 36 % of the total 2012 surface lowering. This interplay between melt and firn properties highlights that the lower accumulation area of the Greenland ice sheet will be responding rapidly in a warming climate. Stability and Variations of Arctic Land Ice (SVALI) Programme for Monitoring of the Greenland Ice Sheet (PROMICE) Greenland Analogue Project (GAP) |
| 英文关键词 | Climate change Greenland ice sheet Accumulation area Automatic weather stations Surface energy balance Melt–albedo feedback Surface mass budget Snow Firn Meltwater Percolation Refreezing Runoff |
| 语种 | 英语 |
| URL | http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-284365 |
| 来源机构 | Uppsala University |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/250343 |
| 推荐引用方式 GB/T 7714 | Charalampidis;Charalampos. Climatology and firn processes in the lower accumulation area of the Greenland ice sheet[D]. Uppsala universitet, Luft-, vatten och landskapslära, Geological Survey of Denmark and Greenland (GEUS), Uppsala,2016. |
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