ASTM_G_159_-_98.pdf

Designation:G 159 98Standard Tables forReferences Solar Spectral Irradiance at Air Mass 1.5:DirectNormal and Hemispherical for a 37 Tilted Surface1This standard is issued under the fixed designation G 159;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(e)indicates an editorial change since the last revision or reapproval.INTRODUCTIONThese tables use the revised(1)2extraterrestrial spectrum of Neckel and Labs(2).In addition,refinements were made to the calculation of atmospheric absorption and scattering in the computercode(3,4)used to calculate the spectrum.These refinements consist of a change in the depolarizationfactor in the Rayleigh scattering calculation,a more accurate sampling technique for calculatingscattered irradiance,and a better choice of wavelengths to perform the calculations.1.Scope1.1 These tables cover an air mass 1.5 solar spectralirradiance distribution for use in all terrestrial applications inwhich a standard reference spectral irradiance is required forthe direct component of solar irradiance and hemisphericalsolar irradiance,consisting of both the diffuse and directcomponents,that is incident on a sun-facing,37-tilted surface.1.2 An air mass of 1.5,a turbidity of 0.27,and a tilt of 37(for the hemispherical spectral irradiance tables)were chosenfor this standard because they are representative of averageconditions in the 48 contiguous states of the United States.Inreal life,a large range of atmospheric conditions can beencountered,resulting in more or less important variations inatmospheric extinction.Thus,considerable departure from thepresent reference spectra might be observed depending on timeof the day,geographical location,and other fluctuating condi-tions in the atmosphere.1.3 These tables are an editorial revision of Tables E 891and Tables E 892,that have been combined.This action hasbeen taken to make the reference solar spectral energy stan-dards harmonious with ISO 9845-1:1992,that was itself basedwholly on Tables E 891 and Tables E 892 with respect to thetables of spectral irradiance values.The tables contained hereare identical to those contained in Tables E 891 and E 892.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:E 490 Solar Constant and Air Mass Zero Solar SpectralIrradiance Tables3E 772 Terminology Relating to Solar Energy Conversion4E 891 Tables for Terrestrial Direct Normal Solar SpectralIrradiance for Air Mass 1.55E 892 Tables for Terrestrial Solar Spectral Irradiance at AirMass 1.5 for a 37 Tilted Surface52.2ISO Standard:ISO 9845-1:1992(E)Solar Energy-Reference Solar Spec-tral Irradiance at the Ground at Different ReceivingConditions-Part 1:Direct Normal and HemisphericalSolar Irradiance for Air Mass 1.563.Terminology3.1 Definitions(from Terminology E 772):3.1.1 air mass(AM)ratio of the mass of atmosphere in theactual observer-sun path to the mass that would exist if theobserver were at sea level,at standard barometric pressure,andthe sun were directly overhead.3.1.1.1 Discussion(Sometimes called air mass ratio.)Airmass varies with the zenith angle of the sun and the localbarometric pressure,that changes with altitude.For sun zenithZ,of 62 or less,and local atmospheric pressure,P,where POis standard atmospheric pressure,AM (P/PO)secZ.3.1.2 solar irradiance,diffuse,Es,ddownward scatteredsolar flux is received on a horizontal surface from a solid angleof 2p-steradian(hemisphere)with the exception of a conicalsolid angle with a 100 mrad(approximately 6)included planeangle centered upon the suns disk.1These tables are under the jurisdiction of ASTM Committee G-03 on Weath-ering and Durability and is the direct responsibility of Subcommittee G03.09 onRadiometry.Current edition approved June 10,1998.Published March 1999.Originallypublished as G 159-98.2The boldface numbers given in parentheses refer to the list of references at theend of the text.3Annual Book of ASTM Standards,Vol 15.03.4Annual Book of ASTM Standards,Vol 12.02.5Annual Book of ASTM Standards,Vol 14.04.6Available from American National Standards Institute,11 W.42nd St.,13thFloor,New York,NY 10036.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTM3.1.3 solar irradiance,direct,Esolar flux coming fromthe solid angle of the suns disk on a surface perpendicular tothe axis of that solid angle.3.1.3.1 DiscussionIn conventional instruments,the ac-ceptance cone includes a plane angle of about 6.3.2 Definitions of Terms Specific to This Standard:3.2.1 air mass zero(AM