气候变化领域集成服务门户(CCPortal): Small-scale variation of snow in a regional permafrost model

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DOI	10.5194/tc-10-1201-2016
	Small-scale variation of snow in a regional permafrost model
	Gisnas K.; Westermann S.; Vikhamar Schuler T.; Melvold K.; Etzelmüller B.
发表日期	2016
ISSN	19940416
卷号	10 期号:3
英文摘要	The strong winds prevalent in high altitude and arctic environments heavily redistribute the snow cover, causing a small-scale pattern of highly variable snow depths. This has profound implications for the ground thermal regime, resulting in highly variable near-surface ground temperatures on the metre scale. Due to asymmetric snow distributions combined with the nonlinear insulating effect of snow, the spatial average ground temperature in a 1 km2 area cannot be determined based on the average snow cover for that area. Land surface or permafrost models employing a coarsely classified average snow depth will therefore not yield a realistic representation of ground temperatures. In this study we employ statistically derived snow distributions within 1 km2 grid cells as input to a regional permafrost model in order to represent sub-grid variability of ground temperatures. This improves the representation of both the average and the total range of ground temperatures. The model reproduces observed sub-grid ground temperature variations of up to 6 °C, and 98% of borehole observations match the modelled temperature range. The mean modelled temperature of the grid cell reproduces the observations with an accuracy of 1.5 °C or better. The observed sub-grid variations in ground surface temperatures from two field sites are very well reproduced, with estimated fractions of sub-zero mean annual ground surface temperatures within ±10 %.We also find that snow distributions within areas of 1 km2 in Norwegian mountain environments are closer to a gamma than to a lognormal theoretical distribution. The modelled permafrost distribution seems to be more sensitive to the choice of distribution function than to the fine-tuning of the coefficient of variation. When incorporating the small-scale variation of snow, the modelled total permafrost area of mainland Norway is nearly twice as large compared to the area obtained with grid-cell average snow depths without a sub-grid approach. © 2016 Author(s).
学科领域	altitude; arctic environment; borehole; estimation method; insulation; land surface; permafrost; snow cover; surface temperature; temperature anomaly; thermal regime; Norway
语种	英语
scopus关键词	altitude; arctic environment; borehole; estimation method; insulation; land surface; permafrost; snow cover; surface temperature; temperature anomaly; thermal regime; Norway
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/119637
作者单位	Department of Geosciences, University of Oslo, Oslo, Norway; Norwegian Water Resources and Energy Dirct., Oslo, Norway
推荐引用方式 GB/T 7714	Gisnas K.,Westermann S.,Vikhamar Schuler T.,et al. Small-scale variation of snow in a regional permafrost model[J],2016,10(3).
APA	Gisnas K.,Westermann S.,Vikhamar Schuler T.,Melvold K.,&Etzelmüller B..(2016).Small-scale variation of snow in a regional permafrost model.Cryosphere,10(3).
MLA	Gisnas K.,et al."Small-scale variation of snow in a regional permafrost model".Cryosphere 10.3(2016).