气候变化领域集成服务门户(CCPortal): Comparison of different methods to retrieve optical-equivalent snow grain size in central Antarctica

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DOI	10.5194/tc-11-2727-2017
	Comparison of different methods to retrieve optical-equivalent snow grain size in central Antarctica
	Carlsen T.; Birnbaum G.; Ehrlich A.; Freitag J.; Heygster G.; Istomina L.; Kipfstuhl S.; Orsi A.; Schäfer M.; Wendisch M.
发表日期	2017
ISSN	19940416
卷号	11 期号:6
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.
学科领域	comparative study; energy budget; grain size; ground-based measurement; metamorphism; MODIS; optical property; polar region; surface energy; uncertainty analysis; wavelet; Antarctica
语种	英语
scopus关键词	comparative study; energy budget; grain size; ground-based measurement; metamorphism; MODIS; optical property; polar region; surface energy; uncertainty analysis; wavelet; Antarctica
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/119302
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
推荐引用方式 GB/T 7714	Carlsen T.,Birnbaum G.,Ehrlich A.,et al. Comparison of different methods to retrieve optical-equivalent snow grain size in central Antarctica[J],2017,11(6).
APA	Carlsen T..,Birnbaum G..,Ehrlich A..,Freitag J..,Heygster G..,...&Wendisch M..(2017).Comparison of different methods to retrieve optical-equivalent snow grain size in central Antarctica.Cryosphere,11(6).
MLA	Carlsen T.,et al."Comparison of different methods to retrieve optical-equivalent snow grain size in central Antarctica".Cryosphere 11.6(2017).