Changes in the surface broadband shortwave radiation budget during the 2017 eclipse

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dc.contributor.authorWen, Guoyong
dc.contributor.authorMarshak, Alexander
dc.contributor.authorTsay, Si-Chee
dc.contributor.authorHerman, Jay
dc.contributor.authorJeong, Ukkyo
dc.contributor.authorAbuhassan, Nader
dc.contributor.authorSwap, Robert
dc.contributor.authorWu, Dong
dc.date.accessioned2022-02-28T14:33:16Z
dc.date.available2022-02-28T14:33:16Z
dc.date.issued2020-09-09
dc.description.abstractWhile 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.en_US
dc.description.sponsorshipThis research was supported by NASA's Interdisciplinary Science for Eclipse 2017 program managed by M. Guhathakurta and partly supported by NASA to the Sun-Climate research. We thank Fred Espenak for providing eclipse parameter calculations. This research has been supported by NASA-ROSES (grant no. NNX17AH67G).en_US
dc.description.urihttps://acp.copernicus.org/articles/20/10477/2020/acp-20-10477-2020.htmlen_US
dc.format.extent15 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2mqgr-welj
dc.identifier.citationWen, G., Marshak, A., Tsay, S.-C., Herman, J., Jeong, U., Abuhassan, N., Swap, R., and Wu, D.: Changes in the surface broadband shortwave radiation budget during the 2017 eclipse, Atmos. Chem. Phys., 20, 10477–10491, https://doi.org/10.5194/acp-20-10477-2020, 2020.en_US
dc.identifier.urihttps://doi.org/10.5194/acp-20-10477-2020
dc.identifier.urihttp://hdl.handle.net/11603/24326
dc.language.isoen_USen_US
dc.publisherEGUen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Joint Center for Earth Systems Technology
dc.relation.ispartofUMBC Faculty Collection
dc.rightsThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C.105, no copyright protection is available for such works under U.S. Law.en_US
dc.rightsPublic Domain Mark 1.0*
dc.rights.urihttp://creativecommons.org/publicdomain/mark/1.0/*
dc.titleChanges in the surface broadband shortwave radiation budget during the 2017 eclipseen_US
dc.typeTexten_US
dcterms.creatorhttps://orcid.org/0000-0002-9146-1632en_US

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