Aerosol ultraviolet absorption experiment (2002 to 2004), part 1: ultraviolet multifilter rotating shadowband radiometer calibration and intercomparison with CIMEL sunphotometers

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dc.contributor.authorKrotkov, Nickolay
dc.contributor.authorBhartia, Pawan K.
dc.contributor.authorHerman, Jay
dc.contributor.authorSlusser, James R.
dc.contributor.authorLabow, Gordon J.
dc.contributor.authorScott, Gwendolyn R.
dc.contributor.authorJanson, George T.
dc.contributor.authorEck, Thomas
dc.contributor.authorHolben, Brent N.
dc.date.accessioned2023-07-11T21:29:20Z
dc.date.available2023-07-11T21:29:20Z
dc.date.issued2005-04-01
dc.description.abstractRadiative transfer calculations of UV irradiance from total ozone mapping spectrometer (TOMS) satellite data are frequently overestimated compared to ground-based measurements because of the presence of undetected absorbing aerosols in the planetary boundary layer. To reduce these uncertainties, an aerosol UV absorption closure experiment has been conducted at the National Aeronautics and Space Administration/Goddard Space Flight Center (NASA/GSFC) site in Greenbelt, Maryland, using 17 months of data from a shadowband radiometer [UV-multifilter rotating shadowband radiometer (UV-MFRSR), U.S. Department of Agriculture (USDA) UV-B Monitoring and Research Network] colocated with a group of three sun-sky CIMEL radiometers [rotating reference instruments of the NASA Aerosol Robotic Network (AERONET)]. We describe an improved UV-MFRSR on-site calibration method augmented by AERONET-CIMEL measurements of aerosol extinction optical thickness (τₐ) interpolated or extrapolated to the UV-MFRSR wavelengths and measurement intervals. The estimated τₐ is used as input to a UV-MFRSR spectral-band model, along with independent column ozone and surface pressure measurements, to estimate zero air mass voltages V₀ in three longer wavelength UV-MFRSR channels (325, 332, 368 nm). Daily mean ⟨V₀⟩, estimates and standard deviations are obtained for cloud-free conditions and compared with the on-site UV-MFRSR Langley plot calibration method. By repeating the calibrations on clear days, relatively good stability (±2% in ⟨V₀⟩) is found in summer, with larger relative changes in fall-winter seasons. The changes include systematic day-to-day ⟨V₀⟩ decline for extended periods along with step jump changes after major precipitation periods (rain or snow) that affected the diffuser transmission. When daily ⟨V₀⟩ values are used to calculate τₐ for individual 3-min UV-MFRSR measurements on the same days, the results compare well with interpolated AERONET τₐ measurements [at 368 nm most daily 1σ root mean square (rms) differences were within 0.01]. When intercalibrated against an AERONET sunphotometer, the UV-MFRSR is proven reliable to retrieve τₐ, and hence can be used to retrieve aerosol column absorption in the UV. The advantage of the shadowband technique is that the calibration obtained for direct-sun voltage can then be applied to diffuse-radiance voltage to obtain total and diffuse atmospheric transmittances. These transmittances, in combination with accurate τₐ data, provide the basis for estimating aerosol column absorption at many locations of the USDA UV-B Monitoring and Research network and for correction of satellite estimations of surface UV irradiance.en_US
dc.description.urihttps://www.spiedigitallibrary.org/journals/optical-engineering/volume-44/issue-4/041004/Aerosol-ultraviolet-absorption-experiment-2002-to-2004-part-1/10.1117/1.1886818.fullen_US
dc.format.extent17 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2ruux-oumh
dc.identifier.citationNickolay A. Krotkov, Pawan K. Bhartia, Jay R. Herman, James R. Slusser, Gordon J. Labow, Gwendolyn R. Scott, George T. Janson, Tom Eck, Brent N. Holben, "Aerosol ultraviolet absorption experiment (2002 to 2004), part 1: ultraviolet multifilter rotating shadowband radiometer calibration and intercomparison with CIMEL sunphotometers," Opt. Eng. 44(4) 041004 (1 April 2005) https://doi.org/10.1117/1.1886818en_US
dc.identifier.urihttps://doi.org/10.1117/1.1886818
dc.identifier.urihttp://hdl.handle.net/11603/28592
dc.language.isoen_USen_US
dc.publisherSPIEen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC GESTAR II Collection
dc.relation.ispartofUMBC Joint Center for Earth Systems Technology (JCET)
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.titleAerosol ultraviolet absorption experiment (2002 to 2004), part 1: ultraviolet multifilter rotating shadowband radiometer calibration and intercomparison with CIMEL sunphotometersen_US
dc.title.alternativeUV aerosol absorption experiment (2002-04): 1. UV-MFRSR calibration and performance at GSFCen_US
dc.typeTexten_US
dcterms.creatorhttps://orcid.org/0000-0001-6170-6750en_US
dcterms.creatorhttps://orcid.org/0000-0002-9146-1632en_US

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