1、Designation: G173 03 (Reapproved 2012)Standard Tables forReference Solar Spectral Irradiances: Direct Normal andHemispherical on 37 Tilted Surface1This standard is issued under the fixed designation G173; the number immediately following the designation indicates the year oforiginal adoption or, in
2、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.INTRODUCTIONA wide variety of solar spectral energy distributions occur in the natural environme
3、nt and aresimulated by artificial sources during product, material, or component testing. To compare the relativeoptical performance of spectrally sensitive products a reference standard solar spectral distribution isrequired. These tables replace ASTM standard G159, which has been withdrawn. The so
4、lar spectralenergy distribution presented in this standard are not intended as a benchmark for ultraviolet radiationin weathering exposure testing of materials. The spectra are based on version 2.9.2 of the SimpleModel of the Atmospheric Radiative Transfer of Sunshine (SMARTS) atmospheric transmissi
5、on code(1,2).2SMARTS uses empirical parameterizations of version 4.0 of the Air Force GeophysicalLaboratory (AFGL) Moderate Resolution Transmission model, MODTRAN (3,4) for some gaseousabsorption processes, and recent spectroscopic data for others. An extraterrestrial spectrum differingonly slightly
6、 from the extraterrestrial spectrum in Tables E490 is used to calculate the resultant spectra(5). The hemispherical tilted spectrum is similar to the hemispherical spectrum in use since 1987, butdiffers from it because: (1) the wavelength range for the current spectrum has been extended deeperinto t
7、he ultraviolet; (2) uniform wavelength intervals are now used; (3) more representativeatmospheric conditions are represented,; and (4) SMARTS Version 2.9.2 has been used as thegenerating model. For the same reasons, and particularly the adoption of a remarkably less turbidatmosphere than before, sig
8、nificant differences exist in the reference direct normal spectrum comparedto previous versions of this standard. The input parameters used in conjunction with SMARTS for theselected atmospheric conditions are tabulated. The SMARTS model and documentation are availableas an adjunct (ADJG173CD3) to t
9、his standard.1. Scope1.1 These tables contain terrestrial solar spectral irradiancedistributions for use in terrestrial applications that require astandard reference spectral irradiance for hemispherical solarirradiance (consisting of both direct and diffuse components)incident on a sun-facing, 37 t
10、ilted surface or the direct normalspectral irradiance. The data contained in these tables reflectreference spectra with uniform wavelength interval (0.5 nano-meter (nm) below 400 nm, 1 nm between 400 and 1700 nm, anintermediate wavelength at 1702 nm, and 5 nm intervals from1705 to 4000 nm). The data
11、 tables represent reasonablecloudless atmospheric conditions favorable for photovoltaic(PV) energy production, as well as weathering and durabilityexposure applications.1.2 The 37 slope of the sun-facing tilted surface waschosen to represent the average latitude of the 48 contiguousUnited States. A
12、wide variety of orientations is possible forexposed surfaces. The availability of the SMARTS model (asan adjunct, ADJG173CD3) to this standard) used to generatethe standard spectra allows users to evaluate differencesrelative to the surface specified here.1.3 The air mass and atmospheric extinction
13、parameters arechosen to provide (1) historical continuity with respect toprevious standard spectra, (2) reasonable cloudless atmo-spheric conditions favorable for photovoltaic (PV) energyproduction or weathering and durability exposure, based uponmodern broadband solar radiation data, atmospheric pr
14、ofiles,and improved knowledge of aerosol optical depth profiles. Innature, an extremely large range of atmospheric conditions can1These tables are under the jurisdiction ofASTM Committee G03 on Weatheringand Durability and is the direct responsibility of Subcommittee G03.09 onRadiometry.Current edit
15、ion approved Nov. 1, 2012. Published November 2012. Originallyapproved in 2003. Last previous edition approved in 2008 as G17303(2008). DOI:10.1520/G0173-03R12.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3Available from ASTM International Headquart
16、ers. 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 States1be encountered even under cloudless skies. Considerabledeparture from the reference spectra may be observed depend-ing
17、on time of day, geographical location, and changingatmospheric conditions. The availability of the SMARTSmodel (as an adjunct (ADJG173CD3)to this standard) used togenerate the standard spectra allows users to evaluate spectraldifferences relative to the spectra specified here.2. Referenced Documents
18、2.1 ASTM Standards:4E490 Standard Solar Constant and Zero Air Mass SolarSpectral Irradiance TablesE772 Terminology of Solar Energy Conversion2.2 ASTM Adjunct:3ADJG173CD Simple Model for Atmospheric Transmissionof Sunshine3. Terminology3.1 DefinitionsDefinitions of most terms used in thisspecificatio
19、n may be found in Terminology E772.3.2 Definitions:The following definition differs from that inTerminology E772, representing information current as of thisrevision.3.2.1 solar constantthe total solar irradiance at normalincidence on a surface in free space at the earths meandistance from the sun.
20、(1 astronomical unit, or AU = 1.496 1011m).3.2.1.1 DiscussionThe solar constant is now knownwithin about 61.5 Wm-2. Its current accepted values are1366.1 Wm-2(Tables E490) or 1367.0 Wm-2(World Meteo-rological Organization, WMO), and are subject to change. Dueto the eccentricity of the earths orbit,
21、the actual extraterrestrialsolar irradiance varies by 63.4 % about the solar constant asthe earth-sun distance varies through the year. Throughout thisstandard the solar constant is defined as 1367.0 Wm-2.3.3 Definitions of Terms Specific to This Standard:3.3.1 aerosol optical depth (AOD)the wavelen
22、gth-dependent total extinction (scattering and absorption) by aero-sols in the atmosphere. This optical depth (also called “opticalthickness”) is defined here at 500 nm.3.3.1.1 DiscussionSee Appendix X1.3.3.2 air mass zero (AM0)describes solar radiation quan-tities outside the Earths atmosphere at t
23、he mean Earth-Sundistance (1 Astronomical Unit). See Tables E490.3.3.3 integrated irradiance E1-2spectral irradiance inte-grated over a specific wavelength interval from 1to 2,measured in Wm-2; mathematically:E1225 *12Ed (1)3.3.4 solar irradiance, hemispherical EHon a given plane,the solar radiant f
24、lux received from within the 2 steradian fieldof view of a tilted plane from the portion of the sky dome andthe foreground included in the planes field of view, includingboth diffuse and direct solar radiation.3.3.4.1 DiscussionFor the special condition of a horizon-tal plane the hemispherical solar
25、 irradiance is properly termedglobal solar irradiance, 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 ad
26、jective global should refer only tohemispherical solar radiation on a horizontal, not a tilted,surface.3.3.5 solar irradiance, spectral Esolar irradiance E perunit wavelength interval at a given wavelength (unit: Wattsper square meter per nanometer, Wm-2nm-1):E5dEd(2)3.3.6 spectral intervalthe dista
27、nce in wavelength unitsbetween adjacent spectral irradiance data points.3.3.7 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)
28、and theincident spectral irradiance produces the effective transmittedirradiance.3.3.7.1 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
29、 of the filter or deviceoccurs, or as full-width at half-maximum, FWHM.3.3.8 spectral resolutionthe minimum wavelength differ-ence between two wavelengths that can be identified unam-biguously.3.3.8.1 DiscussionIn the context of this standard, thespectral resolution is simply the interval, , between
30、 spectraldata points, or the spectral interval.3.3.9 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-cmor atm-cm).3.3.10 total precipitable waterthe depth of a column ofwater (with a
31、 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).3.3.11 wavenumbera unit of frequency, , in units ofreciprocal centimeters (symbol cm-1) commonly used in placeof wavelength, (units of length, typically nano
32、meters). Toconvert wavenumber to nanometers, nm=1107/ cm-1.See X1.2.4. Significance and Use4.1 Absorptance, reflectance, and transmittance of solarenergy are important factors in material degradation studies,solar thermal system performance, solar photovoltaic systemperformance, biological studies,
33、and solar simulation activities.These optical properties are normally functions of wavelength,which require the spectral distribution of the solar flux be4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMS
34、tandards volume information, refer to the standards Document Summary page onthe ASTM website.G173 03 (Reapproved 2012)2known before the solar-weighted property can be calculated.To compare the relative performance of competitive products,or to compare the performance of products before and afterbein
35、g subjected to weathering or other exposure conditions, areference standard solar spectral distribution is desirable.4.2 These tables provide appropriate standard spectral irra-diance distributions for determining the relative optical perfor-mance of materials, solar thermal, solar photovoltaic, and
36、 othersystems. The tables may be used to evaluate components andmaterials for the purpose of solar simulation where either thedirect or the hemispherical (that is, direct beam plus diffusesky) spectral solar irradiance is desired. However, these tablesare not intended to be used as a benchmark for u
37、ltravioletradiation used in indoor exposure testing of materials usingmanufactured light sources.4.3 The total integrated irradiances for the direct and hemi-spherical tilted spectra are 900.1 Wm-2and 1000.4 Wm-2,respectively. Note that, in PV applications, no amplitudeadjustments are required to ma
38、tch standard reporting conditionirradiances of 1000 Wm-2for hemispherical irradiance.4.4 Previously defined global hemispherical reference spec-trum (G159) for a sun-facing 37-tilted surface served well tomeet the needs of the flat plate photovoltaic research,development, and industrial community. I
39、nvestigation of pre-vailing conditions and measured spectra shows that this globalhemispherical reference spectrum can be attained in practiceunder a variety of conditions, and that these conditions can beinterpreted as representative for many combinations of atmo-spheric parameters. Earlier global
40、hemispherical referencespectrum may be closely, but not exactly, reproduced withimproved spectral wavelength range, uniform spectral interval,and spectral resolution equivalent to the spectral interval, usinginputs in X1.4.4.5 Reference spectra generated by the SMARTS Version2.9.2 model for the indi
41、cated conditions are shown in Fig. 1.The exact input file structure required to generate the referencespectra is shown in Table 1.4.6 The availability of the adjunct (ADJG173CD3) standardcomputer software for SMARTS allows one to (1) reproducethe reference spectra, using the above input parameters;
42、(2)compute test spectra to attempt to match measured data at aspecified FWHM, and evaluate atmospheric conditions; and (3)compute test spectra representing specific conditions for analy-sis vis-vis any one or all of the reference spectra.4.7 Differences from the previous standard spectra (G159)can b
43、e summarized as follows:4.7.1 Extended spectral interval in the ultraviolet (down to280 nm, rather than 305 nm),4.7.2 Better resolution (2002 wavelengths, as compared to120),4.7.3 Constant intervals (0.5 nm below 400 nm, 1 nmbetween 400 and 1700 nm, and 5 nm above),4.7.4 Better definition of atmosph
44、eric scattering and gas-eous absorption, with more species considered,4.7.5 Better defined extraterrestrial spectrum,4.7.6 More realistic spectral ground reflectance, andFIG. 1 Plot of Direct Normal Spectral Irradiance (Solid Line) and Hemispherical Spectral Irradiance on 37 Tilted Sun-Facing Surfac
45、e(Dotted Line) Computed Using Smarts Version 2.9.2 Model With Input File in Table 1G173 03 (Reapproved 2012)34.7.7 Lower aerosol optical depth, yielding significantlylarger direct normal irradiance.5. Technical Bases for the Tables5.1 These tables are modeled data generated using an airmass zero (AM
46、0) spectrum based in part on the extraterrestrialspectrum of Kurucz (5), the 1976 U.S. Standard Atmosphere(6), the Shettle and Fenn Rural Aerosol Profile (7), theSMARTS radiative transfer code, version 2.9.2, and associatedinput data files.5.2 In order to provide spectral data with a uniform spectra
47、lstep size and improved spectral resolution, the AM0 spectrumused in conjunction with SMARTS to generate the terrestrialspectrum is slightly different from the ASTM extraterrestrialspectrum, Standard E490. Because Standard E490 andSMARTS both use the Kurucz data, the SMARTS and TablesE490 spectra ar
48、e in good agreement though they do not havethe same spectral interval step sizes, spectral interval centers,or spectral resolution.5.3 The 1976 U.S. Standard Atmosphere (USSA) is used toprovide documented atmospheric properties and concentra-tions of absorbers. However, some newly documented (andrel
49、atively minor) absorbers are taken into consideration in thepresent standard spectra. See X1.3.5.4 The SMARTS model code and documentation is avail-able from the NREL(National Renewable Energy Lab) website(www.nrel.gov).5.5 These terrestrial solar spectral data are based on thework of Gueymard (1,2) and Gueymard et al. (8). Previouslydefined reference spectra were based on the work of Bird,Hulstrom, and Lewis (9). The current spectra reflect current (asof 2002) improved knowledge of gaseous absorption, atmo-spheric a
