气候变化领域集成服务门户(CCPortal): Intercomparison and improvement of two-stream shortwave radiative transfer schemes in Earth system models for a unified treatment of cryospheric surfaces

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DOI	10.5194/tc-13-2325-2019
	Intercomparison and improvement of two-stream shortwave radiative transfer schemes in Earth system models for a unified treatment of cryospheric surfaces
	Dang C.; Zender C.S.; Flanner M.G.
发表日期	2019
ISSN	19940416
EISSN	13
起始页码	2325
结束页码	2343
卷号	13 期号:9
英文摘要	Snow is an important climate regulator because it greatly increases the surface albedo of middle and high latitudes of the Earth. Earth system models (ESMs) often adopt two-stream approximations with different radiative transfer techniques, the same snow therefore has different solar radiative properties depending whether it is on land or on sea ice. Here we intercompare three two-stream algorithms widely used in snow models, improve their predictions at large zenith angles, and introduce a hybrid model suitable for all cryospheric surfaces in ESMs. The algorithms are those employed by the SNow ICe and Aerosol Radiative (SNICAR) module used in land models, dEdd-AD used in Icepack, the column physics used in the Los Alamos sea ice model CICE and MPAS-Seaice, and a two-stream discrete-ordinate (2SD) model. Compared with a 16-stream benchmark model, the errors in snow visible albedo for a direct-incident beam from all three two-stream models are small (< ±0:005) and increase as snow shallows, especially for aged snow. The errors in direct near-infrared (near-IR) albedo are small (< ±0:005) for solar zenith angles ° < 75°, and increase as ° increases. For diffuse incidence under cloudy skies, dEdd-AD produces the most accurate snow albedo for both visible and near-IR (< ±0:0002) with the lowest underestimate (-0:01) for melting thin snow. SNICAR performs similarly to dEdd-AD for visible albedos, with a slightly larger underestimate (-0:02), while it overestimates the near-IR albedo by an order of magnitude more (up to 0.04). 2SD overestimates both visible and near-IR albedo by up to 0.03. We develop a new parameterization that adjusts the underestimated direct nearIR albedo and overestimated direct near-IR heating persistent across all two-stream models for ° > 75°. These results are incorporated in a hybrid model SNICAR-AD, which can now serve as a unified solar radiative transfer model for snow in ESM land, land ice, and sea ice components. © 2018 The Author(s).
语种	英语
来源期刊	The Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/118842
作者单位	Department of Earth System Science, University of California, Irvine, CA, United States; Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, United States
推荐引用方式 GB/T 7714	Dang C.,Zender C.S.,Flanner M.G.. Intercomparison and improvement of two-stream shortwave radiative transfer schemes in Earth system models for a unified treatment of cryospheric surfaces[J],2019,13(9).
APA	Dang C.,Zender C.S.,&Flanner M.G..(2019).Intercomparison and improvement of two-stream shortwave radiative transfer schemes in Earth system models for a unified treatment of cryospheric surfaces.The Cryosphere,13(9).
MLA	Dang C.,et al."Intercomparison and improvement of two-stream shortwave radiative transfer schemes in Earth system models for a unified treatment of cryospheric surfaces".The Cryosphere 13.9(2019).