1、Designation: G177 03 (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
2、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
3、 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 v
4、ariety 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
5、 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 emp
6、irical 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 hemispherica
7、l (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
8、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 l
9、ight 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 compr
10、ised 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
11、 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-
12、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 expo
13、sure 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 ofAS
14、TM 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 boldfa
15、ce 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. Unit
16、ed States12. 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 t
17、erms 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-Sundistance (1 Astronomical Unit). See AS
18、TM E490.3.2.2 integrated irradiance E12spectral irradiance inte-grated over a specific wavelength interval from 1to 2,measured in Wm-2; mathematically:E1225 *12Ed (1)3.2.3 solar irradiance, hemispherical EHon a given plane,the solar radiant flux received from the within the 2- steradianfield of view
19、 of a tilted plane from the portion of the sky domeand the foreground included in the planes field of view,including both diffuse and direct solar radiation.3.2.3.1 DiscussionFor the special condition of a horizon-tal plane the hemispherical solar irradiance is properly termedglobal solar irradiance
20、, EG. Incorrectly, global tilted, or totalglobal irradiance is often used to indicate hemisphericalirradiance for a tilted plane. In case of a sun-tracking receiver,this hemispherical irradiance is commonly called global nor-mal irradiance. The adjective global should refer only tohemispherical sola
21、r radiation on a horizontal, not a tilted,surface.3.2.4 aerosol optical depth (AOD)the wavelength-dependent total extinction (scattering and absorption) by aero-sols in the atmosphere. This optical depth (also called “opticalthickness”) is defined here at 500 nm.3.2.4.1 DiscussionSee X1.1.3.2.5 sola
22、r irradiance, spectral Esolar irradiance E perunit wavelength interval at a given wavelength . (Unit: Wattsper square meter per nanometer, Wm-2nm-1)E5dEd(2)3.2.6 spectral passbandthe effective wavelength intervalwithin which spectral irradiance is allowed to pass, as througha filter or monochromator
23、. The convolution integral of thespectral passband (normalized to unity at maximum) and theincident spectral irradiance produces the effective transmittedirradiance.3.2.6.1 DiscussionSpectral passband may also be referredto as the spectral bandwidth of a filter or device. Passbands areusually specif
24、ied as the interval between wavelengths at whichone half of the maximum transmission of the filter or deviceoccurs, or as full-width at half-maximum, FWHM.3.2.7 spectral intervalthe distance in wavelength unitsbetween adjacent spectral irradiance data points.3.2.8 spectral resolutionthe minimum wave
25、length differ-ence between two wavelengths that can be identified unam-biguously.3.2.8.1 DiscussionIn the context of this standard, thespectral resolution is simply the interval, , between spectraldata points, or the spectral interval.3.2.9 total precipitable waterthe depth of a column ofwater (with
26、 a section of 1 cm2) equivalent to the condensedwater vapor in a vertical column from the ground to the top ofthe atmosphere. (Unit: cm or g/cm2)3.2.10 total ozonethe depth of a column of pure ozoneequivalent to the total of the ozone in a vertical column fromthe ground to the top of the atmosphere.
27、 (Unit: atmosphere-cm)3.2.11 wavenumbera unit of frequency, , in units ofreciprocal centimeters (symbol cm-1) commonly used in placeof wavelength, . The relationship between wavelength andfrequency is defined by = c, where c is the speed of light invacuum. To convert wavenumber to nanometers, nm = 1
28、107/cm-1.4. Technical Basis for the Tables4.1 These tables are modeled data generated using an airmass zero (AM0) spectrum based on the extraterrestrial spec-trum of of Gueymard (1,2) derived from Kurucz (5), the UnitedStates Standard Atmosphere of 1976 (USSA) reference Atmo-sphere (6), the Shettle
29、and Fenn Rural Aerosol Profile (7), theSMARTS2 V. 2.9.2 radiative transfer code. Further details areprovided in X1.3.4.2 The 37 tilted surface was selected as it represents theaverage latitude of the contiguous forty-eight states of thecontinental U.S., and outdoor exposure testing often takesplace
30、at latitude tilt.4.3 The documented USSA atmospheric profiles utilized inthe MODTRAN spectral transmission model (6) have beenused to provide atmospheric properties and concentrations ofabsorbers.4.4 The SMARTS model Version 2.9.2 is available atInternet URL: http:/rredc.nrel.gov/solar/models/SMARTS
31、.4.5 To provide spectral data with a uniform spectral stepsize, theAM0 spectrum used in conjunction with SMARTS2 togenerate the terrestrial spectrum is slightly different from theASTM extraterrestrial spectrum,ASTM E490. BecauseASTME490 and SMARTS2 both use the data of Kurucz (5), theSMARTS2 and E49
32、0 spectra are in excellent agreementalthough they do not have the same spectral resolution.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume Information, refer to the standards Document Su
33、mmary Page onthe ASTM website.G177 03 (Reapproved 2012)24.6 The current spectra reflect improved knowledge ofatmospheric aerosol optical properties, transmission properties,and radiative transfer modeling (8).4.7 The terrestrial solar spectral in the tables have beencomputed with a spectral bandwidt
34、h equivalent to the spectralresolution of the tables, namely 0.5 nm.5. Significance and Use5.1 This standard does not purport to address the mean levelof solar ultraviolet spectral irradiance to which materials willbe subjected during their useful life. The spectral irradiancedistributions have been
35、 chosen to represent a reasonable upperlimit for natural solar ultraviolet radiation that ought to beconsidered when evaluating the behavior of materials undervarious exposure conditions.5.2 Absorptance, reflectance, and transmittance of solarenergy are important factors in material degradation stud
36、ies.These properties are normally functions of wavelength, whichrequire that the spectral distribution of the solar flux be knownbefore the solar-weighted property can be calculated.5.3 The interpretation of the behavior of materials exposedto either natural solar radiation or ultraviolet radiation
37、fromartificial light sources requires an understanding of the spectralenergy distribution employed. To compare the relative perfor-mance of competitive products, or to compare the performanceof products before and after being subjected to weathering orother exposure conditions, a reference standard
38、solar spectraldistribution is desirable.5.4 A plot of the SMARTS2 model output for the referencehemispherical UV radiation on a 37 south facing tilted surfaceis shown in Fig. 1. The input needed by SMARTS2 to generatethe spectrum for the prescribed conditions are shown in Table1.5.5 SMARTS2 Version
39、2.9.2 is required to generate AM1.05 UV reference spectra.5.6 The availability of the adjunct standard computer soft-ware (ADJG173CD5) for SMARTS2 allows one to (1) repro-duce the reference spectra, using the above input parameters;(2) compute test spectra to attempt to match measured data ata speci
40、fied FWHM, and evaluate atmospheric conditions; and(3) compute test spectra representing specific conditions foranalysis vis-vis any one or all of the reference spectra.6. Solar Spectral Irradiance6.1 Table 2 presents the reference spectral irradiance dataglobal hemispherical solar irradiance on a p
41、lane tilted at 37toward the equator, for the conditions specified in Table 1.6.2 The table contains:6.2.1 Hemispherical solar spectral irradiance incident on anequator-facing5plane tilted to 37 from the horizontal in thewavelength range from 280 to 400 nm.6.2.2 The columns in each table contain:6.2.
42、2.1 Column 1: Wavelength in nanometers (nm).6.2.2.2 Column 2: Mean hemispherical spectral irradianceincident on surface tilted 37 toward the equator. E,Wm-2nm-1.7. Validation7.1 In part of the spectral region of interest, (295 to 400 nm)the SMARTS2 model has been verified against experimentaldata. S
43、MARTS2 performance is adequate for the region from295 to 400 nm. No reliable experimental data has been foundto verify performance below 295 nm.7.2 Comparisons of the SMARTS2 computer model withboth MODTRAN model results and measured spectral data andother rigorous spectral models are reported in (1
44、,2). Fig. 2 is aplot of the relative magnitude of the spectral differencesobserved between MODTRAN version 4.0 and SMARTS2 foridentical conditions. Results indicate that the various modelsare within 5 % in spectral regions where significant energy ispresent.7.3 Comparison of these reference spectra
45、with clear skysolar spectral irradiance data from various spectrometers undervarious atmospheric conditions approximating those chosen forthis data are in reasonable agreement (8).8. Keywords8.1 global hemispherical; materials exposure; terrestrial;ultraviolet solar spectral irradiance5South facing
46、for the northern hemisphere, north facing for the southernhemisphere.G177 03 (Reapproved 2012)3FIG. 1 Total Hemispherical Ultraviolet Reference Spectra Based on SMARTS2 Runs for AM1.05 UV Spectral Profile (a) Linear Scale; (b)Logarithmic ScaleG177 03 (Reapproved 2012)4TABLE 1 SMARTS Version 2.9.2 In
47、put File to Generate the Reference SpectraCard ID Value Parameter/Description/Variable Name1 ASTM UV_Std_Spectra Header2 1 Pressure input mode (1 = pressure and altitude): ISPR2a 820.0 2.0. Station Pressure (mb) and altitude (km): SPR, ALT3 1 Standard Atmosphere Profile Selection (1 = use default at
48、mosphere): IATM13a USSA Default Standard Atmosphere Profile: ATM4 1 Water Vapor Input (1 = default from Atmospheric Profile): IH2O5 0 Ozone Calculation (0 = user input concentariont and altitude): IO35a 1 0.3 Ozone Atltitude correctiom (IALT =1=correctfromsealevel), OzoneConcentration (AbO3 = 0.30 a
49、tm cm)6 1 Pollution level mode (1 = standard conditions/no pollution): IGAS (see X1.3)7 370 Carbon Monoxide volume mixing ratio (ppm): qCO2 (see X1.3)7a 1 Extraterrestrial Spectrum (1 = SMARTS/Gueymard): ISPCTR8 S or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).G177 03 (Reapproved 2012)10
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