1、Designation: G 177 03e1Standard Tables forReference Solar Ultraviolet Spectral Distributions:Hemispherical on 37 Tilted Surface1This standard is issued under the fixed designation G 177; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEThe reference to ADJG173CD was added editorially in March 2006.INTRODUCTIONThese tables of solar ultraviole
3、t (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 s
4、olar 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 subj
5、ected 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 para
6、meterizations 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 E 490 is used to calculate theresultant spectra. The hemispherical (2p ster
7、adian 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 f
8、or each set of conditions are tabulated. TheSMARTS2 model and documentation are available as an adjunct (ADJG0173CD3)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 sou
9、rces may be judgedwhen applied to indoor exposure testing. The table provides areference for comparison with natural sunlight ultravioletspectral data. The ultraviolet reference spectral irradiance isprovidded for the wavelength range from 280 to 400 nm. Thewavelength region selected is comprised of
10、 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-
11、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) equ
12、ivalent thichkness.1.3 The data contained in these tables were generated usingthe SMARTS2 Version 2.9.2 atmospheric transmission modeldeveloped by Gueymard (1,2).1These tables are under the jurisdiction ofASTM Committee G03 onWeatheringand Durability and is the direct responsibility of Subcommittee
13、G03.09 onRadiometry.Current edition approved Sept. 10, 2003. Published November 2003.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3Available from ASTM International Headquarters. Order Adjunct No.ADJG173CD.1Copyright ASTM International, 100 Barr Har
14、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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
15、adjunct(ADJG0173CD3)to this standard) used to generate the standardspectra allows users to evaluate spectral differences relative tothe spectra specified here.2. Referenced Documents2.1 ASTM Standards:4E 490 Standard Solar Constant and Zero Air Mass SolarSpectral Irradiance TablesE 772 Terminology R
16、elating to Solar Energy Conversion2.2 ASTM Adjunct:ADJG0173CD Simple Model for Atmospheric Transmis-sion of Sunshine43. Terminology3.1 DefinitionsDefinitions of terms used in this specifica-tion not otherwise described below may be found in Terminol-ogy E 772.3.2 Definitions of Terms Specific to Thi
17、s 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 ASTM E 490.3.2.2 integrated irradiance El1l2spectral irradiance in-tegrated over a specific wavelength interval from l1to l2,measured in Wm
18、-2; mathematically:El1 2l25*l1l2Eldl (1)3.2.3 solar irradiance, hemispherical EHon a given plane,the solar radiant flux received from the within the 2-p steradianfield of view of a tilted plane from the portion of the sky domeand the foreground included in the planes field of view,including both dif
19、fuse 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, EG. Incorrectly, global tilted, or totalglobal irradiance is often used to indicate hemisphericalirradiance for a tilted pl
20、ane. In case of a sun-tracking receiver,this hemispherical irradiance is commonly called global nor-mal irradiance. The adjective global should refer only tohemispherical solar radiation on a horizontal, not a tilted,surface.3.2.4 aerosol optical depth (AOD)the wavelength-dependent total extinction
21、(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 solar irradiance, spectral Elsolar irradiance E perunit wavelength interval at a given wavelength l. (Unit: Wattsper square meter
22、 per nanometer, Wm-2nm-1)El5dEdl(2)3.2.6 spectral passbandthe effective wavelength intervalwithin which spectral irradiance is allowed to pass, as througha filter or monochromator. The convolution integral of thespectral passband (normalized to unity at maximum) and theincident spectral irradiance p
23、roduces the effective transmittedirradiance.3.2.6.1 DiscussionSpectral passband may also be referredto as the spectral bandwidth of a filter or device. Passbands areusually specified as the interval between wavelengths at whichone half of the maximum transmission of the filter or deviceoccurs, or as
24、 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 wavelength differ-ence between two wavelengths that can be identified unam-biguously.3.2.8.1 DiscussionIn the context of this
25、 standard, thespectral resolution is simply the interval, Dl, between spectraldata points, or the spectral interval.3.2.9 total precipitable waterthe depth of a column ofwater (with a section of 1 cm2) equivalent to the condensedwater vapor in a vertical column from the ground to the top ofthe atmos
26、phere. (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. (Unit: atmosphere-cm)3.2.11 wavenumbera unit of frequency, y, in units ofreciprocal centimeters (symbol cm-1) commonly
27、 used in placeof wavelength, l. The relationship between wavelength andfrequency is defined by ly = c, where c is the speed of light invacuum. To convert wavenumber to nanometers, lnm = 1107/ycm-1.4. Technical Basis for the Tables4.1 These tables are modeled data generated using an airmass zero (AM0
28、) 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 and Fenn Rural Aerosol Profile (7), theSMARTS2 V. 2.9.2 radiative transfer code. Further details areprovided in
29、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 at latitude tilt.4.3 The documented USSA atmospheric profiles utilized inthe MODTRAN spectral transmission model
30、 (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.4.5 To provide spectral data with a uniform spectral stepsize, theAM0 spectrum used in conjunction with SMARTS2
31、 togenerate the terrestrial spectrum is slightly different from theASTM extraterrestrial spectrum, ASTM E 490. BecauseASTM E 490 and SMARTS2 both use the data of Kurucz (5),4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For A
32、nnual Book of ASTMStandards volume Information, refer to the standards Document Summary Page onthe ASTM website.G17703e12the SMARTS2 and E 490 spectra are in excellent agreementalthough they do not have the same spectral resolution.4.6 The current spectra reflect improved knowledge ofatmospheric aer
33、osol optical properties, transmission properties,and radiative transfer modeling (8).4.7 The terrestrial solar spectral in the tables have beencomputed with a spectral bandwidth equivalent to the spectralresolution of the tables, namely 0.5 nm.5. Significance and Use5.1 This standard does not purpor
34、t to address the mean levelof solar ultraviolet spectral irradiance to which materials willbe subjected during their useful life. The spectral irradiancedistributions have been chosen to represent a reasonable upperlimit for natural solar ultraviolet radiation that ought to beconsidered when evaluat
35、ing the behavior of materials undervarious exposure conditions.5.2 Absorptance, reflectance, and transmittance of solarenergy are important factors in material degradation studies.These properties are normally functions of wavelength, whichrequire that the spectral distribution of the solar flux be
36、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 fromartificial light sources requires an understanding of the spectralenergy distribution employed. To compare the relative
37、perfor-mance of competitive products, or to compare the performanceof products before and after being subjected to weathering orother exposure conditions, a reference standard solar spectraldistribution is desirable.5.4 A plot of the SMARTS2 model output for the referencehemispherical UV radiation o
38、n 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 2.9.2 is required to generate AM1.05 UV reference spectra.5.6 The availability of the adjunct standard computer soft-ware (A
39、DJG0173CD5) 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 specified FWHM, and evaluate atmospheric conditions; and(3) compute test spectra representing specific conditions foranalysis vi
40、s-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 plane tilted at 37toward the equator, for the conditions specified in Table 1.6.2 The table contains:6.2.1 Hemispherical sol
41、ar 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:6.2.2.1 Column 1: Wavelength in nanometers (nm).6.2.2.2 Column 2: Mean hemispherical spectral irradianceincident on surface til
42、ted 37 toward the equator. El,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. SMARTS2 performance is adequate for the region from295 to 400 nm. No reliable experimental data has been foundto verify per
43、formance 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 (1,2). Fig. 2 is aplot of the relative magnitude of the spectral differencesobserved between MODTRAN version 4.0 and SMARTS2
44、 foridentical conditions. Results indicate that the various modelsare within 5 % in spectral regions where significant energy ispresent.7.3 Comparison of these reference spectra with clear skysolar spectral irradiance data from various spectrometers undervarious atmospheric conditions approximating
45、those chosen forthis data are in reasonable agreement (8).8. Keywords8.1 global hemispherical; materials exposure; terrestrial;ultraviolet solar spectral irradiance5South facing for the northern hemisphere, north facing for the southernhemisphere.G17703e13FIG. 1 Total Hemispherical Ultraviolet Refer
46、ence Spectra Based on SMARTS2 Runs for AM1.05 UV Spectral Profile (a) Linear Scale; (b)Logarithmic ScaleG17703e14TABLE 1 SMARTS Version 2.9.2 Input File to Generate the Reference SpectraCard ID Value Parameter/Description/Variable Name1 ASTM UV_Std_Spectra Header2 1 Pressure input mode (1 = pressure
47、 and altitude): ISPR2a 820.0 2.0. Station Pressure (mb) and altitude (km): SPR, ALT3 1 Standard Atmosphere Profile Selection (1 = use defaultatmosphere): IATM13a USSA Default Standard Atmosphere Profile: ATM4 1 Water Vapor Input (1 = default from Atmospheric Profile): IH2O5 0 Ozone Calculation (0 =
48、user input concentariont and altitude): IO35a 1 0.3 Ozone Atltitude correctiom (IALT =1=correctfromsealevel),Ozone Concentration (AbO3 = 0.30 atm 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).G17703e110
