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Regional climate-model performance in Greenland firn derived from in situ observations
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Geological Survey of Denmark and Greenland (GEUS). (Ice, Climate and Environment)ORCID iD: 0000-0003-0853-697X
Geological Survey of Denmark and Greenland (GEUS).ORCID iD: 0000-0002-6553-8982
Danish Meteorological Institute (DMI).
Geological Survey of Denmark and Greenland (GEUS).
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2016 (English)In: Geological Survey of Denmark and Greenland Bulletin, ISSN 1811-4598, E-ISSN 1604-8156, Vol. 35, 75-78 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Copenahgen, Denmark, 2016. Vol. 35, 75-78 p.
Keyword [en]
Regional climate model, RCM, Greenland ice sheet, firn, automatic weather stations, AWS
National Category
Environmental Sciences
Identifiers
URN: urn:nbn:se:uu:diva-284359ISI: 000383915800018OAI: oai:DiVA.org:uu-284359DiVA: diva2:920214
Projects
Stability and Variations of Arctic Land Ice (SVALI)Programme for Monitoring of the Greenland Ice Sheet (PROMICE)Understanding and predicting non-linear change in the permeability of Greenland firn (RETAIN)
Available from: 2016-04-17 Created: 2016-04-17 Last updated: 2017-11-30Bibliographically approved
In thesis
1. Climatology and firn processes in the lower accumulation area of the Greenland ice sheet
Open this publication in new window or tab >>Climatology and firn processes in the lower accumulation area of the Greenland ice sheet
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 81 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1372
Keyword
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
National Category
Climate Research Environmental Sciences Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:uu:diva-284365 (URN)978-91-554-9571-8 (ISBN)
Public defence
2016-06-10, Hambergsalen, Geocentrum, Villavägen 16, Uppsala, 10:15 (English)
Opponent
Supervisors
Projects
Stability and Variations of Arctic Land Ice (SVALI)Programme for Monitoring of the Greenland Ice Sheet (PROMICE)Greenland Analogue Project (GAP)
Available from: 2016-05-20 Created: 2016-04-17 Last updated: 2016-06-15

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Charalampidis, Charalamposvan As, DirkBox, Jason E.

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