气候变化领域集成服务门户(CCPortal): A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: Application to Greenland

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DOI	10.5194/tc-10-727-2016
	A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: Application to Greenland
	Wang W.; Zender C.S.; Van As D.; Smeets P.C.J.P.; Van Den Broeke M.R.
发表日期	2016
ISSN	19940416
卷号	10 期号:2
英文摘要	Surface melt and mass loss of the Greenland Ice Sheet may play crucial roles in global climate change due to their positive feedbacks and large fresh-water storage. With few other regular meteorological observations available in this extreme environment, measurements from automatic weather stations (AWS) are the primary data source for studying surface energy budgets, and for validating satellite observations and model simulations. Station tilt, due to irregular surface melt, compaction and glacier dynamics, causes considerable biases in the AWS shortwave radiation measurements. In this study, we identify tilt-induced biases in the climatology of surface shortwave radiative flux and albedo, and retrospectively correct these by iterative application of solar geometric principles. We found, over all the AWS from the Greenland Climate Network (GC-Net), the Kangerlussuaq transect (K-transect) and the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) networks, insolation on fewer than 40% of clear days peaks within ±0.5h of solar noon time, with the largest shift exceeding 3h due to tilt. Hourly absolute biases in the magnitude of surface insolation can reach up to 200W m-2, with respect to the well-understood clear-day insolation. We estimate the tilt angles and their directions based on the solar geometric relationship between the simulated insolation at a horizontal surface and the observed insolation by these tilted AWS under clear-sky conditions. Our adjustment reduces the root mean square error (RMSE) against references from both satellite observation and reanalysis by 16W m-2 (24%), and raises the correlation coefficients with them to above 0.95. Averaged over the whole Greenland Ice Sheet in the melt season, the adjustment in insolation to compensate station tilt is ∼ 11W m-2, enough to melt 0.24m of snow water equivalent. The adjusted diurnal cycles of albedo are smoother, with consistent semi-smiling patterns. The seasonal cycles and inter-annual variabilities of albedo agree better with previous studies. This tilt-corrected shortwave radiation data set derived using the Retrospective, Iterative, Geometry-Based (RIGB) method provide more accurate observations and validations for surface energy budgets studies on the Greenland Ice Sheet, including albedo variations, surface melt simulations and cloud radiative forcing estimates. © Author(s) 2016.
学科领域	albedo; climate change; cloud radiative forcing; data set; energy budget; geometry; model validation; satellite; shortwave radiation; surface energy; weather station; Arctic; Greenland; Greenland Ice Sheet; Kangerlussuaq Fjord
语种	英语
scopus关键词	albedo; climate change; cloud radiative forcing; data set; energy budget; geometry; model validation; satellite; shortwave radiation; surface energy; weather station; Arctic; Greenland; Greenland Ice Sheet; Kangerlussuaq Fjord
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/119679
作者单位	Department of Earth System Science, University of California, Irvine, CA, United States; Geological Survey of Denmark and Greenland (GEUS), Copenhagen, Denmark; Institute for Marine and Atmospheric Research, Utrecht University (UU/IMAU), Utrecht, Netherlands
推荐引用方式 GB/T 7714	Wang W.,Zender C.S.,Van As D.,et al. A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: Application to Greenland[J],2016,10(2).
APA	Wang W.,Zender C.S.,Van As D.,Smeets P.C.J.P.,&Van Den Broeke M.R..(2016).A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: Application to Greenland.Cryosphere,10(2).
MLA	Wang W.,et al."A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: Application to Greenland".Cryosphere 10.2(2016).