ASTM_G_177_-_03_2012.pdf

Designation:G17703(Reapproved 2012)Standard Tables forReference Solar Ultraviolet Spectral Distributions:Hemispherical on 37 Tilted Surface1This standard is issued under the fixed designation G177;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEThe title to Table 2 was corrected editorially in August 2008.INTRODUCTIONThese tables of solar ultraviolet(UV)spectral irradiance values have been developed to meet theneed for a standard ultraviolet reference spectral energy distribution to be used as a reference for theupper limit of ultraviolet radiation in the outdoor weathering of materials and related indoor exposurestudies.A wide variety of solar spectral energy distributions occur in the natural environment and aresimulated by artificial sources during product,material,or component testing.To compare the relativeoptical performance of spectrally sensitive products,or to compare the performance of products beforeand after being subjected to weathering or other exposure conditions,a reference standard solarspectral distribution is required.These tables were prepared using version 2.9.2 of the Simple Modelof theAtmospheric Radiative Transfer of Sunshine(SMARTS2)atmospheric transmission code(1,2).2SMARTS2 uses empirical parameterizations of version 4.0 of the Air Force Geophysical Laboratory(AFGL)Moderate Resolution Transmission model,MODTRAN(3,4).An extraterrestrial spectrumdiffering only slightly from the extraterrestrial spectrum in ASTM E490 is used to calculate theresultant spectra.The hemispherical(2 steradian acceptance angle)spectral irradiance on a paneltilted 37(average latitude of the contiguous United States)to the horizontal is tabulated.Thewavelength range for the spectra extends from 280 to 400 nm,with uniform wavelength intervals.Theinput parameters used in conjunction with SMARTS2 for each set of conditions are tabulated.TheSMARTS2 model and documentation are available as an adjunct ADJG173CD3)to this standard.1.Scope1.1 The table provides a standard ultraviolet spectral irradi-ance distribution that maybe employed as a guide againstwhich manufactured ultraviolet light sources may be judgedwhen applied to indoor exposure testing.The table provides areference for comparison with natural sunlight ultravioletspectral data.The ultraviolet reference spectral irradiance isprovided for the wavelength range from 280 to 400 nm.Thewavelength region selected is comprised of the UV-A spectralregion from 320 to 400 nm and the UV-B region from 280 to320 nm.1.2 The table defines a single ultraviolet solar spectralirradiance distribution:1.2.1 Total hemispherical ultraviolet solar spectral irradi-ance(consisting of combined direct and diffuse components)incident on a sun-facing,37 tilted surface in the wavelengthregion from 280 to 400 nm for air mass 1.05,at an elevation of2 km(2000 m)above sea level for the United States StandardAtmosphere profile for 1976(USSA 1976),excepting for theozone content which is specified as 0.30 atmosphere-centimeters(atm-cm)equivalent thickness.1.3 The data contained in these tables were generated usingthe SMARTS2 Version 2.9.2 atmospheric transmission modeldeveloped by Gueymard(1,2).1.4 The climatic,atmospheric and geometric parametersselected reflect the conditions to provide a realistic maximumultraviolet exposure under representative clear sky conditions.1.5 The availability of the SMARTS2 model(as an adjunct(ADJG173CD3)to this standard)used to generate the standardspectra allows users to evaluate spectral differences relative tothe spectra specified here.1These tables are under the jurisdiction ofASTM Committee G03 on Weatheringand Durability and is the direct responsibility of Subcommittee G03.09 onRadiometry.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 2003.Last previous edition approved in 2008 as G177 03(2008)e1.DOI:10.1520/G0177-03R12.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3Available from ASTM International Headquarters.Order Adjunct No.ADJG173CD.Original adjunct produced in 2005.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.Referenced Documents2.1 ASTM Standards:4E490 Standard Solar Constant and Zero Air Mass SolarSpectral Irradiance TablesE772 Terminology of Solar Energy Conversion2.2 ASTM Adjuncts:ADJG173CD Simple Model for Atmospheric Transmissionof Sunshine33.Terminology3.1 DefinitionsDefinitions of terms used in this specifica-tion not otherwise described below may be found in Terminol-ogy E772.3.2 Definitions of Terms Specific to This Standard:3.2.1 air mass zero(AM0)describes solar radiation quan-tities outside the Earths atmosphere at the mean Earth-Sundistanc