DOI: 10.5194/tc-11-2727-2017
Scopus记录号: 2-s2.0-85035747896
论文题名: Comparison of different methods to retrieve optical-equivalent snow grain size in central Antarctica
作者: Carlsen T ; , Birnbaum G ; , Ehrlich A ; , Freitag J ; , Heygster G ; , Istomina L ; , Kipfstuhl S ; , Orsi A ; , Schäfer M ; , Wendisch M
刊名: Cryosphere
ISSN: 19940416
出版年: 2017
卷: 11, 期: 6 起始页码: 2727
结束页码: 2741
语种: 英语
英文关键词: comparative study
; energy budget
; grain size
; ground-based measurement
; metamorphism
; MODIS
; optical property
; polar region
; surface energy
; uncertainty analysis
; wavelet
; Antarctica
英文摘要: The optical-equivalent snow grain size affects the reflectivity of snow surfaces and, thus, the local surface energy budget in particular in polar regions. Therefore, the specific surface area (SSA), from which the optical snow grain size is derived, was observed for a 2-month period in central Antarctica (Kohnen research station) during austral summer 2013/14. The data were retrieved on the basis of ground-based spectral surface albedo measurements collected by the COmpact RAdiation measurement System (CORAS) and airborne observations with the Spectral Modular Airborne Radiation measurement sysTem (SMART). The snow grain size and pollution amount (SGSP) algorithm, originally developed to analyze spaceborne reflectance measurements by the MODerate Resolution Imaging Spectroradiometer (MODIS), was modified in order to reduce the impact of the solar zenith angle on the retrieval results and to cover measurements in overcast conditions. Spectral ratios of surface albedo at 1280 and 1100 nm wavelength were used to reduce the retrieval uncertainty. The retrieval was applied to the ground-based and airborne observations and validated against optical in situ observations of SSA utilizing an IceCube device. The SSA retrieved from CORAS observations varied between 27 and 89 m2 kg-1. Snowfall events caused distinct relative maxima of the SSA which were followed by a gradual decrease in SSA due to snow metamorphism and wind-induced transport of freshly fallen ice crystals. The ability of the modified algorithm to include measurements in overcast conditions improved the data coverage, in particular at times when precipitation events occurred and the SSA changed quickly. SSA retrieved from measurements with CORAS and MODIS agree with the in situ observations within the ranges given by the measurement uncertainties. However, SSA retrieved from the airborne SMART data slightly underestimated the ground-based results. © Author(s) 2017. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/75471
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: Leipzig Institute for Meteorology, University of Leipzig, Leipzig, Germany; Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany; Institute of Environmental Physics, University of Bremen, Bremen, Germany; Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France
Recommended Citation:
Carlsen T,, Birnbaum G,, Ehrlich A,et al. Comparison of different methods to retrieve optical-equivalent snow grain size in central Antarctica[J]. Cryosphere,2017-01-01,11(6)