DOI: 10.5194/tc-8-1069-2014
Scopus记录号: 2-s2.0-84903203099
论文题名: Albedo over rough snow and ice surfaces
作者: Lhermitte S ; , Abermann J ; , Kinnard C
刊名: Cryosphere
ISSN: 19940416
出版年: 2014
卷: 8, 期: 3 起始页码: 1069
结束页码: 1086
语种: 英语
英文关键词: albedo
; complex terrain
; ground-based measurement
; radiative transfer
; satellite data
; snow
; surface roughness
; Andes
; Chile
; Coquimbo
; Tapado Glacier
英文摘要: Both satellite and ground-based broadband albedo measurements over rough and complex terrain show several limitations concerning feasibility and representativeness. To assess these limitations and understand the effect of surface roughness on albedo, firstly, an intrasurface radiative transfer (ISRT) model is combined with albedo measurements over different penitente surfaces on Glaciar Tapado in the semi-arid Andes of northern Chile. Results of the ISRT model show effective albedo reductions over the penitentes up to 0.4 when comparing the rough surface albedo relative to the albedo of the flat surface. The magnitude of these reductions primarily depends on the opening angles of the penitentes, but the shape of the penitentes and spatial variability of the material albedo also play a major role. Secondly, the ISRT model is used to reveal the effect of using albedo measurements at a specific location (i.e., apparent albedo) to infer the true albedo of a penitente field (i.e., effective albedo). This effect is especially strong for narrow penitentes, resulting in sampling biases of up to ±0.05. The sampling biases are more pronounced when the sensor is low above the surface, but remain relatively constant throughout the day. Consequently, it is important to use a large number of samples at various places and/or to locate the sensor sufficiently high in order to avoid this sampling bias of surface albedo over rough surfaces. Thirdly, the temporal evolution of broadband albedo over a penitente-covered surface is analyzed to place the experiments and their uncertainty into a longer temporal context. Time series of albedo measurements at an automated weather station over two ablation seasons reveal that albedo decreases early in the ablation season. These decreases stabilize from February onwards with variations being caused by fresh snowfall events. The 2009/2010 and 2011/2012 seasons differ notably, where the latter shows lower albedo values caused by larger penitentes. Finally, a comparison of the ground-based albedo observations with Landsat and MODIS (Moderate Resolution Imaging Spectroradiometer)-derived albedo showed that both satellite albedo products capture the albedo evolution with root mean square errors of 0.08 and 0.15, respectively, but also illustrate their shortcomings related to temporal resolution and spatial heterogeneity over small mountain glaciers. © Author(s) 2014. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/74833
Appears in Collections: 影响、适应和脆弱性 气候变化与战略
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作者单位: Centro de Estudios Avanzados en Zonas Áridas (CEAZA), La Serena, Chile; Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands; KU Leuven, Department of Earth and Environmental Sciences, Leuven, Belgium; Asiaq, Greenland Survey, Nuuk, Greenland; Université du Québec À Trois-Rivières, Département des Sciences de l'Environnement, Trois-Rivières, QC, Canada
Recommended Citation:
Lhermitte S,, Abermann J,, Kinnard C. Albedo over rough snow and ice surfaces[J]. Cryosphere,2014-01-01,8(3)