气候变化领域集成服务门户(CCPortal): The darkening of the Greenland ice sheet: Trends, drivers, and projections (1981-2100)

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DOI	10.5194/tc-10-477-2016
	The darkening of the Greenland ice sheet: Trends, drivers, and projections (1981-2100)
	Tedesco M.; Doherty S.; Fettweis X.; Alexander P.; Jeyaratnam J.; Stroeve J.
发表日期	2016
ISSN	19940416
卷号	10 期号:2
英文摘要	The surface energy balance and meltwater production of the Greenland ice sheet (GrIS) are modulated by snow and ice albedo through the amount of absorbed solar radiation. Here we show, using space-borne multispectral data collected during the 3 decades from 1981 to 2012, that summertime surface albedo over the GrIS decreased at a statistically significant (99 %) rate of 0.02g decade-1 between 1996 and 2012. Over the same period, albedo modelled by the Modèle Atmosphérique Régionale (MAR) also shows a decrease, though at a lower rate (∼-0.01 decade-1) than that obtained from space-borne data. We suggest that the discrepancy between modelled and measured albedo trends can be explained by the absence in the model of processes associated with the presence of light-absorbing impurities. The negative trend in observed albedo is confined to the regions of the GrIS that undergo melting in summer, with the dry-snow zone showing no trend. The period 1981-1996 also showed no statistically significant trend over the whole GrIS. Analysis of MAR outputs indicates that the observed albedo decrease is attributable to the combined effects of increased near-surface air temperatures, which enhanced melt and promoted growth in snow grain size and the expansion of bare ice areas, and to trends in light-absorbing impurities (LAI) on the snow and ice surfaces. Neither aerosol models nor in situ and remote sensing observations indicate increasing trends in LAI in the atmosphere over Greenland. Similarly, an analysis of the number of fires and BC emissions from fires points to the absence of trends for such quantities. This suggests that the apparent increase of LAI in snow and ice might be related to the exposure of a "dark band" of dirty ice and to increased consolidation of LAI at the surface with melt, not to increased aerosol deposition. Albedo projections through to the end of the century under different warming scenarios consistently point to continued darkening, with albedo anomalies averaged over the whole ice sheet lower by 0.08 in 2100 than in 2000, driven solely by a warming climate. Future darkening is likely underestimated because of known underestimates in modelled melting (as seen in hindcasts) and because the model albedo scheme does not currently include the effects of LAI, which have a positive feedback on albedo decline through increased melting, grain growth, and darkening. © Author(s) 2016.
学科领域	aerosol; air temperature; albedo; consolidation; energy balance; ice sheet; meltwater; remote sensing; snow cover; solar radiation; surface energy; Arctic; Greenland; Greenland Ice Sheet
语种	英语
scopus关键词	aerosol; air temperature; albedo; consolidation; energy balance; ice sheet; meltwater; remote sensing; snow cover; solar radiation; surface energy; Arctic; Greenland; Greenland Ice Sheet
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119695
作者单位	Lamont-Doherty Earth Observatory, Columbia University, New York, Palisades, NY, United States; NASA, Goddard Institute of Space Studies, New York, NY, United States; City College of New York - CUNY, New York, NY, United States; University of Liege, Liege, Belgium; Graduate Center of the City University of New York, New York, NY, United States; University of Boulder, Boulder, CO, United States
推荐引用方式 GB/T 7714	Tedesco M.,Doherty S.,Fettweis X.,et al. The darkening of the Greenland ice sheet: Trends, drivers, and projections (1981-2100)[J],2016,10(2).
APA	Tedesco M.,Doherty S.,Fettweis X.,Alexander P.,Jeyaratnam J.,&Stroeve J..(2016).The darkening of the Greenland ice sheet: Trends, drivers, and projections (1981-2100).Cryosphere,10(2).
MLA	Tedesco M.,et al."The darkening of the Greenland ice sheet: Trends, drivers, and projections (1981-2100)".Cryosphere 10.2(2016).