1、Designation: E816 05 (Reapproved 2010)E816 15Standard Test Method forCalibration of Pyrheliometers by Comparison to ReferencePyrheliometers1This standard is issued under the fixed designation E816; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e 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.INTRODUCTIONAccurate and precise measurement of the direct (beam) radiation component of sunlight arere
3、quired in (1) the calibration of reference pyranometers by the shading disk or optical occludingmethods, (2) determination of the energy collected by concentrating solar collectors, includingexposure levels achieved in use of Practice G90 dealing with Fresnel-reflecting concentrator testmachines, an
4、d (3) the assessment of the direct beam for energy budget analyses, geographic mappingof solar energy, and as an aid in the determination of the concentration of aerosol and particulatepollution, and water vapor effects.This test method requires calibration to the World Radiometric Reference (WRR),
5、maintained bythe World Meteorological Organization (WMO), Geneva. The Intercomparison of Absolute CavityPyrheliometers, also called Absolute Cavity Radiometers, on which the WRR depends, is covered byprocedures adopted by WMO and by various U.S. Organizations who occasionally convene suchintercompar
6、isons for the purpose of transferring the WRR to the United States, and to maintaining theWRR in the United States. These procedures are not covered by this test method.1. Scope1.1 This test method has been harmonized with, and is technically equivalent to, ISO 9059.1.2 Two types of calibrations are
7、 covered by this test method. One is the calibration of a secondary reference pyrheliometerusing an absolute cavity pyrheliometer as the primary standard pyrheliometer, and the other is the transfer of calibration from asecondary reference to one or more field pyrheliometers. This test method proscr
8、ibesprescribes the calibration procedures and thecalibration hierarchy, or traceability, for transfer of the calibrations.NOTE 1It is not uncommon, and is indeed desirable, for both the reference and field pyrheliometers to be of the same manufacturer and modeldesignation.1.3 This test method is rel
9、evant primarily for the calibration of reference pyrheliometers with field angles of 5 to 6, using asthe primary reference instrument a self-calibrating absolute cavity pyrheliometer having field angles of about 5. Pyrheliometerswith field angles greater than 6.5 shall not be designated as reference
10、 pyrheliometers.1.4 When this test method is used to transfer calibration to field pyrheliometers having field angles both less than 5 or greaterthan 6.5, it will be necessary to employ the procedure defined by Angstrom and Rodhe.21.5 This test method requires that the spectral response of the absol
11、ute cavity chosen as the primary standard pyrheliometer benonselective over the range from 0.3 to 10 m wavelength. Both reference and field pyrheliometers covered by this test methodshall be nonselective over a range from 0.3 to 4 m wavelength.1.6 The primary and secondary reference pyrheliometers s
12、hall not be field instruments and their exposure to sunlight shall belimited to calibration or intercomparisons. These reference instruments shall be stored in an isolated cabinet or room equipped withstandard laboratory temperature and humidity control.NOTE 2At a laboratory where calibrations are p
13、erformed regularly, it is advisable to maintain a group of two or three secondary reference1 This test method is under the jurisdiction ofASTM Committee G03 on Weathering and Durabilityand is the direct responsibility of Subcommittee G03.09 on Radiometry.Current edition approved Dec. 1, 2010Feb. 1,
14、2015. Published December 2010February 2015. Originally approved in 1981. Last previous edition approved in 20052010as E816 05.E816 05(2010). DOI: 10.1520/E0816-05R10.10.1520/E0816-15.2 Angstrom, A., and Rodhe, B., “Pyrheliometric Measurements with Special Regard to the Circumsolar Sky Radiation,” Te
15、llus, Vol 18, 1966, pp. 2533.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends
16、 that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1pyrheliometers that
17、 are included in every calibration. These serve as controls to detect any instability or irregularity in the standard referencepyrheliometer.1.7 This test method is applicable to calibration procedures using natural sunshine only.2. Referenced Documents2.1 ASTM Standards:3E772 Terminology of Solar E
18、nergy ConversionE824 Test Method for Transfer of Calibration From Reference to Field RadiometersG90 Practice for Performing Accelerated Outdoor Weathering of Nonmetallic Materials Using Concentrated Natural SunlightG167 Test Method for Calibration of a Pyranometer Using a Pyrheliometer2.2 ISO Standa
19、rds:4ISO 9059 Calibration of Field Pyrheliometers by Comparison to a Reference PyrheliometerISO 9060 Specification and Classification of Instruments for Measuring Hemispherical Solar and Direct Solar RadiationISO TR 9673 The Instrumental Measurement of Sunlight for Determining Exposure LevelsISO 984
20、6 Calibration of a Pyranometer Using a Pyrheliometer2.3 WMO Standard:Guide to Meteorological Instruments and Methods of Observation, FifthSeventh ed., WMO-No. 853. Terminology3.1 Definitions:3.1.1 The relevant definitions of Terminology E772 apply to the calibration method described in this test met
21、hod.3.1.2 absolute cavity pyrheliometersee self-calibrating absolute cavity pyrheliometer.3.1.3 direct radiation, direct solar radiation, and direct (beam) radiationradiation received from a small solid angle centeredon the suns disk, on a given plane whose normal (perpendicular to the plane) points
22、 to the center of the suns disk (see ISO 9060).That component of sunlight is the beam between an observer, or instrument, and the sun within a solid conical angle centered onthe suns disk and having a total included planar field angle of, for the purposes of this test method, 5 to 6.3.1.4 field pyrh
23、eliometerpyrheliometers that are designed and used for long-term field measurements of direct solar radiation.These pyrheliometers are weatherproof and therefore possess windows, usually quartz, at the field aperture that pass all solarradiation in the range from 0.3 to 4 m wavelength.3.1.5 opening
24、anglewith radius of field aperture denoted by R and the distance between the field and receiver aperturesdenoted by l, the opening angle is defined for right circular cones by the equation:Zo 5 tan21 R/l (1)The field angle is double the opening angle.3.1.6 primary standard pyrheliometerspyrheliomete
25、rs, selected from the group of absolute pyrheliometers (see self-calibrating absolute cavity pyrheliometer).3.1.7 reference pyrheliometerpyrheliometers of any category serving as a reference in calibration transfer procedures. Theyare selected and well-tested instruments (see Table 2 of ISO 9060), t
26、hat have a low rate of yearly change in responsivity. Thereference pyrheliometer may be of the same type, class, and manufacturer as the field radiometers in which case it is speciallychosen for calibration transfer purposes and is termed a secondary standard pyrheliometer (see ISO 9060), or it may
27、be of theself-calibrating cavity type (see self-calibrating absolute cavity pyrheliometer).3.1.8 secondary standard pyrheliometerpyrheliometers of high precision and stability whose calibration factors are derivedfrom primary standard pyrheliometers. This group comprises absolute cavity pyrheliomete
28、rs that do not fulfill the requirements ofa primary standard pyrheliometer as described in 3.1.6.3.1.9 self-calibrating absolute cavity pyrheliometera radiometer consisting of either a single- or dual-conical heated cavitythat, during the self-calibration mode, displays the power required to produce
29、 a thermopile reference signal that is identical to thesampling signal obtained when viewing the sun with an open aperture. The reference signal is produced by the thermopile inresponse to the cavity irradiance resulting from heat supplied by a cavity heater with the aperture closed.3.1.10 slope ang
30、lewith radius of the sensor denoted by r, the radius of the limiting aperture is denoted by R, and the distancebetween aperture and sensor denoted by l, the slope angle equation is defined as:S 5arcTanR 2 r!l (2)3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Cust
31、omer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.International Organi
32、zation forStandardization (ISO), 1, ch. de la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http:/www.iso.org.5 Available from World Meterological Organization, Geneva, Switzerland. 7bis, avenue de la Paix, CP. 2300, CH-1211 Geneva 2, Switzerland, www.wmo.int.E816 1523.2 Acronyms:3.2.1 ACRAbso
33、lute Cavity Radiometer3.2.2 ANSIAmerican National Standards Institute3.2.3 ARMAtmospheric RadiationMeasurement Program3.2.4 DOEDepartment of Energy3.2.5 GUM(ISO) Guide to Uncertainty in Measurements3.2.6 IPCInternational Pyrheliometer comparison3.2.7 ISOInternational Standards Organization3.2.8 NCSL
34、National Council of Standards Laboratories3.2.9 NISTNational Institute of Standards and Technology3.2.10 NRELNational Renewable Energy Laboratory3.2.11 PMODPhysical Meteorological Observatory Davos3.2.12 SACSingapore Accreditation Council3.2.13 SINGLASSingapore Laboratory Accreditation Service3.2.14
35、 UKASUnited Kingdom Accrediation Service3.2.15 WRCWorld Radiation Center3.2.16 WRRWorld Radiometric Reference3.2.17 WMOWorld Meteorological Organization4. Significance and Use4.1 Though the sun trackers employed, the number of instantaneous readings, and the data acquisition equipment used will vary
36、from instrument to instrument and from laboratory to laboratory, this test method provides for the minimum acceptable conditions,procedures, and techniques required.4.2 While the greatest accuracy will be obtained when calibrating pyrheliometers with a self-calibrating absolute cavitypyrheliometer t
37、hat has been demonstrated by intercomparison to be within 60.5 % of the mean irradiance of a family of similarabsolute instruments, acceptable accuracy can be achieved by careful attention to the requirements of this test method whentransferring calibration from a secondary reference to a field pyrh
38、eliometer.4.3 By meeting the requirements of this test method, traceability of calibration to the World Radiometric Reference (WRR) canbe achieved through one or more of the following recognized intercomparisons:4.3.1 International Pyrheliometric Comparison (IPC) VII, Davos, Switzerland, held in 199
39、0, and every five years thereafter, andthe PMO-2 absolute cavity pyrheliometer that is the primary reference instrument of WMO.64.3.2 Any WMO-sanctioned intercomparison of self-calibrating absolute cavity pyrheliometers held in WMO Region IV (Northand Central America).4.3.3 Any sanctioned or non-san
40、ctioned intercomparison held in the United States the purpose of which is to transfer the WRRfrom the primary reference absolute cavity pyrheliometer maintained as the primary reference standard of the United States by theNational Oceanic and Atmospheric Administrations Solar Radiation Facility in B
41、oulder, CO.74.3.4 Any future intercomparisons of comparable reference quality in which at least one self-calibrating absolute cavitypyrheliometer is present that participated in IPC VII or a subsequent IPC, and in which that pyrheliometer is treated as theintercomparisons reference instrument.4.3.5
42、Any of the absolute radiometers participating in the above intercomparisons and being within 60.5 % of the mean of allsimilar instruments compared in any of those intercomparisons.4.4 The calibration transfer method employed assumes that the accuracy of the values obtained are independent of time of
43、 yearand, within the constraints imposed, time of day of measurements. With respect to time of year, the requirement for normalincidence dictates a tile angle from the horizontal that is dependent on the suns zenith angle and, thus, the air mass limits for thattime of year and time of day.5. Interfe
44、rences5.1 Radiation SourceTransfer of calibration from reference to secondary standard or field pyrheliometers is accomplished byexposing the two instruments to the same radiation field and comparing their corresponding measurands. The direct irradianceshould not be less than 300 Wm2, but irradiance
45、 values exceeding 700 Wm2 is preferred.5.2 Sky ConditionsThe measurements made in determining the instrument constant shall be performed only under conditionswhen the sun is unobstructed by clouds for an incremental data-taking period. The most acceptable sky conditions should be suchthat the direct
46、 irradiance is not less than 80 % of the hemispherical irradiance measured with a pyranometer aligned with its axisvertical and calibrated in accordance with Test Method G167. Also, no cloud formation may be within 15 of the sun during the6 WRCD, “Results, Seventh International Pyrheliometer Compari
47、sons,” Working Report No. XX, Swiss Meteorological Institute, Zurich, Switzerland, Month, 1991.7 Currently (2005) the TMI/Kendall Absolute Cavity Radiometer, SN 67502 and Eppley Laboratory Model AHF SN 28553.E816 153period data are taken for record when either transferring calibration to a secondary
48、 standard pyrheliometer (to be used as areference pyrheliometer) from an absolute cavity pyrheliometer, or when transferring calibration from a secondary referencepyrheliometer to field pyrheliometers. Generally, good calibration conditions exist when the cloud cover is less than 12.5 %.NOTE 3Contra
49、ils of airplanes that are within 15 of the sun can be tolerated providing the ratio of so affected measurements to unaffectedmeasurements is small in any series.NOTE 4Atmospheric water vapor in the pre-condensation phase occasionally causes variable atmospheric transmission. Generally, the scattering ofmeasuring data that is produced by these clusters is acceptable.5.2.1 The atmospheric turbidity during transfer of calibration should be close to values typical for the field measuringconditions. Generally, the turbidity
