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DOI	10.5194/acp-20-10477-2020
	Changes in the surface broadband shortwave radiation budget during the 2017 eclipse
	Wen G.; Marshak A.; Tsay S.-C.; Herman J.; Jeong U.; Abuhassan N.; Swap R.; Wu D.
发表日期	2020
ISSN	1680-7316
起始页码	10477
结束页码	10491
卷号	20 期号:17
英文摘要	While solar eclipses are known to greatly diminish the visible radiation reaching the surface of the Earth, less is known about the magnitude of the impact. We explore both the observed and modeled levels of change in surface radiation during the eclipse of 2017. We deployed a pyranometer and Pandora spectrometer instrument to Casper, Wyoming, and Columbia, Missouri, to measure surface broadband shortwave (SW) flux and atmospheric properties during the 21 August 2017 solar eclipse event. We performed detailed radiative transfer simulations to understand the role of clouds in spectral and broadband solar radiation transfer in the Earth's atmosphere for the normal (non-eclipse) spectrum and red-shift solar spectra for eclipse conditions. The theoretical calculations showed that the non-eclipse-to-eclipse surface flux ratio depends strongly on the obscuration of the solar disk and slightly on the cloud optical depth. These findings allowed us to estimate what the surface broadband SW flux would be for hypothetical non-eclipse conditions from observations during the eclipse and further to quantify the impact of the eclipse on the surface broadband SW radiation budget. We found that the eclipse caused local reductions of time-averaged surface flux of about 379 W m-2 (50 %) and 329 W m-2 (46 %) during the ∼3 h course of the eclipse at the Casper and Columbia sites, respectively. We estimated that the Moon's shadow caused a reduction of approximately 7 %-8 % in global average surface broadband SW radiation. The eclipse has a smaller impact on the absolute value of surface flux reduction for cloudy conditions than a clear atmosphere; the impact decreases with the increase in cloud optical depth. However, the relative time-averaged reduction of local surface SW flux during a solar eclipse is approximately 45 %, and it is not sensitive to cloud optical depth. The reduction of global average SW flux relative to climatology is proportional to the non-eclipse and eclipse flux difference in the penumbra area and depends on cloud optical depth in the Moon's shadow and geolocation due to the change in solar zenith angle. We also discuss the influence of cloud inhomogeneity on the observed SW flux. Our results not only quantify the reduction of the surface solar radiation budget, but also advance the understanding of broadband SW radiative transfer under solar eclipse conditions. © 2020 Author(s).
语种	英语
scopus关键词	inhomogeneity; optical depth; radiation budget; radiative transfer; shortwave radiation; solar eclipse; surface flux; Columbia [Missouri]; Missouri; United States; Wyoming
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/141111
作者单位	NASA/Goddard Space Flight Center, Code 613, Greenbelt, Maryland 20771, United States; GESTAR/Morgan State University, Baltimore, Maryland 21251, United States; JCET, University of Maryland Baltimore County, Baltimore, Maryland 21250, United States; ESSIC, University of Maryland, College Park, Maryland 20742, United States
推荐引用方式 GB/T 7714	Wen G.,Marshak A.,Tsay S.-C.,et al. Changes in the surface broadband shortwave radiation budget during the 2017 eclipse[J],2020,20(17).
APA	Wen G..,Marshak A..,Tsay S.-C..,Herman J..,Jeong U..,...&Wu D..(2020).Changes in the surface broadband shortwave radiation budget during the 2017 eclipse.Atmospheric Chemistry and Physics,20(17).
MLA	Wen G.,et al."Changes in the surface broadband shortwave radiation budget during the 2017 eclipse".Atmospheric Chemistry and Physics 20.17(2020).