BS-ISO-21348-2007.pdf

BRITISH STANDARD BS ISO 21348:2007 Space environment (natural and artificial) Process for determining solar irradiances ICS 49.140 ? Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 21348:2007 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2007 © BSI 2007 ISBN 978 0 580 50833 2 National foreword This British Standard was published by BSI. It is the UK implementation of ISO 21348:2007. The UK participation in its preparation was entrusted by Technical Committee ACE/68, Space systems and operations, to Panel ACE/68/-/4, Space systems and operations Space environment (natural and artificial). A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Reference number ISO 21348:2007(E) INTERNATIONAL STANDARD ISO 21348 First edition 2007-05-01 Space environment (natural and artificial) Process for determining solar irradiances Environnement spatial (naturel et artificiel) Procédé de détermination des irradiances solaires BS ISO 21348:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Terms and definitions. 1 3 Symbols and abbreviated terms . 2 4 General concept and assumptions. 2 4.1 Solar irradiance representation. 2 4.2 Robustness of standard. 3 4.3 Process-based standard 3 4.4 Process-ownership of standard development. 3 4.5 Parallel activity of certification to standard. 3 5 Solar irradiance product types 3 5.1 Rationale 3 5.2 Type designation 3 6 Solar irradiance spectral categories. 4 6.1 General. 4 6.2 Total Solar Irradiance. 4 6.3 Gamma-rays 4 6.4 X-rays. 5 6.5 Ultraviolet 5 6.6 Visible 6 6.7 Infrared. 6 6.8 Microwave 6 6.9 Radio 7 7 Compliance criteria. 7 7.1 Rationale 7 7.2 Reporting. 8 7.3 Documenting. 8 7.4 Publishing 11 7.5 Archiving . 11 8 Certification. 11 Bibliography. 12 BS ISO 21348:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 21348 was prepared by Technical Committee ISO/TC 20, Aicraft and space vehicles, Subcommittee SC 14, Space systems and operations. BS ISO 21348:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI v Introduction This International Standard provides guidelines for specifying the process of determining solar irradiances. Solar irradiances are reported through products such as measurement sets, reference spectra, empirical models, theoretical models and solar irradiance proxies or indices. These products are used in scientific and engineering applications to characterize within the natural space environment solar irradiances that are relevant to space systems and materials. Examples of applications using input solar irradiance energy include the determination of atmospheric densities for spacecraft orbit determination, attitude control and re-entry calculations, as well as for debris mitigation and collision avoidance activity. Direct and indirect pressure from solar irradiance upon spacecraft surfaces also affects attitude control separately from atmospheric density effects. Solar irradiances are used to provide inputs for a) calculations of ionospheric parameters, b) photon-induced radiation effects, and c) radiative transfer modelling of planetary atmospheres. Input solar irradiance energy is used to characterize material properties related to spacecraft thermal control, including surface temperatures, reflectivity, absorption and degradation. Solar energy applications requiring a standard process for determining solar irradiance energy include solar cell power simulation, material degradation, and the development of lamps and filters for terrestrial solar simulators. A solar irradiance product certifies compliance with this process-based standard by following compliance criteria that are described in this International Standard. The compliance criteria in Clause 7 are based upon solar irradiance product types that are described in Clause 5 and solar irradiance spectral categories described in Clause 6. The method for certifying compliance of a solar irradiance product with this International Standard is provided in Clause 8. BS ISO 21348:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI blank Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 1 Space environment (natural and artificial) Process for determining solar irradiances 1 Scope This International Standard specifies the process for determining solar irradiances and is applicable to measurement sets, reference spectra, empirical models, theoretical models, and solar irradiance proxies or indices that provide solar irradiance products representing parts or all of the solar electromagnetic spectrum. Its purpose is to create a standard method for specifying all solar irradiances for use by space systems and materials users. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 astronomical unit ua AU unit of length approximately equal to the mean distance between the Sun and the Earth with a currently accepted value of (149 597 870 691 ± 3) m See References 1 and 2. NOTE Distances between objects within the solar system are frequently expressed in terms of ua. The ua or AU is a non-SI unit accepted for use with the International System and whose value in SI units is obtained experimentally. Its value is such that, when used to describe the motion of bodies in the solar system, the heliocentric gravitation constant is (0,017 202 098 95)2 ua3 d2, where one day (d) is 86 400 s (see Reference 3). 1 AU is slightly less than the average distance between the Earth and the Sun, since an AU is based on the radius of a Keplerian circular orbit of a point-mass having an orbital period, in days, of 2 /k, where k is the Gaussian gravitational constant and is (0,017 202 098 95 AU3 d2)1/2. The most current published authoritative source for the value of 1 ua is from Reference 2. 2.2 solar irradiance radiation of the Sun integrated over the full disk and expressed in SI units of power through a unit of area, W m2 NOTE The commonly used term “full disk” includes all of the Suns irradiance coming from the solar photosphere and temperature regimes at higher altitudes, including the chromosphere, transition region and corona. Some users refer to these composite irradiances as “whole Sun”. Solar irradiance is more precisely synonymous with “total solar irradiance”, while spectral solar irradiance is the derivative of irradiance with respect to wavelength and can be expressed in SI units of W m3; an acceptable SI submultiple unit description is W m2 nm1. Mixed spectral solar irradiance units (e.g. quanta cm2 s1 nm1, photons cm2 s1 Å1 and ergs cm2 s1 nm1) can be useful as an addition to, but not as a replacement for, SI unit reporting. Solar radiances, or the emergent energy from a spatial area that is less than the full disk of the Sun, are not explicitly covered by this International Standard at the present time unless the radiances are integrated across the full disk to represent an irradiance. BS ISO 21348:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 2 For the calibration of ground-based instruments (pyrheliometers) measuring total solar irradiance (TSI), the World Radiometric Reference (WRR) was introduced in 1980 by the World Meteorological Organisation (WMO) as a primary standard to ensure world-wide homogeneity of solar radiation measurements. The WRR is created through an ensemble of absolute cavity radiometers called the World Standard Group (WSG), located and maintained at the World Radiation Centre by the Physikalisch-Meteorologisches Observatorium Davos in Switzerland. The uncertainty of the WRR is 0,3 %. The comparison of the WRR with the SI scale that is represented by cryogenic radiometers and based on radiance measurements agrees within the quoted uncertainties of the two scales (see References 4 and 5). The transfer of the WRR to space has been done but, because the resulting uncertainty is large compared to the variations of the solar constant, a non- mandatory Space Absolute Radiation Reference (SARR) has been introduced (see Reference 6). 2.3 solar constant S total solar irradiance at normal incidence to the top of the Earths atmosphere through a unit surface and at 1 ua with a mean value of 1 366 W m2 See Reference 7. NOTE The solar constant, a historical term, is not constant. It varies geometrically with the Earths distance from the Sun and physically with the Suns magnetic field activity on short to long timescales, as well as with the observers heliocentric latitude. The value of 1366 W m2 is the measurement communitys current agreement expressed through a TSI space-based composite dataset that is normalized to an arbitrarily selected set of missions defining the SARR (see Reference 6). A range of measured values extends from SORCE/TIM 2003-2004(+?) values (1 362 W m2) to NIMBUS-7/HF 1978-1993 values (1 372 W m2), but also includes SMM/ACRIM I 1980-1989 (1 368 W m2), ERBS/ERBE 1984-2003 (1 365 W m2), UARS/ACRIM II 1991-2001 (1 364 W m2), EURECA/SOVA2 1992-1993 (1 367 W m2), SOHO/VIRGO 1996-2004(+?) (1 366 W m2) and ACRIMSAT/ACRIM III 2000-2004(+?) (1 364 W m2) measurements. The SARR reduces all solar constant space measurements to a single ensemble dataset. The currently measured 1-sigma variation in the composite dataset is approximately 0,6 W m2 and there is a long-term (yearly) smoothed solar cycle minimum to maximum relative variation about the mean value of approximately 1,4 W m2 (see Reference 7). 3 Symbols and abbreviated terms designates the spectral wavelength of solar irradiance and is given in units of length, nm. 4 General concept and assumptions 4.1 Solar irradiance representation Solar irradiance products that are frequently reported to space systems users are derived from measurements and/or models. Examples of solar irradiance products include, but are not limited to spectral and time series intensities, surrogates or substitutes (proxies) and activity indicators (indices) that are intended to represent solar irradiances, and solar images containing full-disk spectral information. Because knowledge of solar irradiance spectral and temporal characteristics is fundamental to the understanding of a wide variety of physical and technical processes, and because solar irradiances have been reported and are used in a variety of formats, it is recognized that the standardization of the process for determining solar irradiances is important. A standardized process for determining solar irradiances enables suppliers and users of these products to exchange information with a common, understandable language. BS ISO 21348:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:41:15 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 3 4.2 Robustness of standard The implementation of this International Standard assumes that there will continue to be technical improvements in the accuracy and precision of measurements, because ground-based and space-based instrumentation use new detectors, filters and computer hardware/software algorithms, and because there is improved understanding of the Suns physical processes. There is also the expectation of continual improvements in the reporting and calculation of reference spectra, empirical models, first-principles model and solar irradiance proxies or indices. It is likely that there will be an evolving solar standard user community. Given the continual change in these areas, this International Standard is designed as a robust document in scope and format, so as to support and encourage these changes. 4.3 Process-based standard This International Standard does not specify one measurement set, one reference spectrum, one solar model or one solar irradiance proxy/index as a single standard. In order to encourage continual improvements in solar irradiance products, this International Standard is a process-based standard for determining solar irradiances. A solar irradiance product, after its development, may follow the process described in Clause 7 to certify compliance with this International Standard. 4.4 Process-ownership of standard development The process owner for developing this International Standard is ISO/TC 20/SC 14/WG 4, or its successor(s). The participants in this process are the delegates and technical experts to ISO/TC 20/SC 14/WG 4. The expe