ISO 21348:2007

Space environment (natural and artificial) — Process for determining solar irradiances

ISO 21348:2007 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.

Environnement spatial (naturel et artificiel) — Procédé de détermination des irradiances solaires

General Information

• Status: Published
• Publication Date: 02-May-2007
• ICS: 49.140 - Space systems and operations
• Technical Committee: ISO/TC 20/SC 14 - Space systems and operations
• Drafting Committee: ISO/TC 20/SC 14 - Space systems and operations
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 10-Mar-2021

Relations

• Consolidated By: ISO 3459:2015 - Plastic piping systems — Mechanical joints between fittings and pressure pipes — Test method for leaktightness under negative pressure
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 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



Reference number
ISO 21348:2007(E)
©
ISO 2007

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ISO 21348:2007(E)
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ISO 21348:2007(E)
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

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ISO 21348:2007(E)
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.
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ISO 21348:2007(E)
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.

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INTERNATIONAL STANDARD ISO 21348:2007(E)

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
2 3 −2
(0,017 202 098 95) ua d , 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 π/k, where k is the
3 −2 1/2
Gaussian gravitational constant and is (0,017 202 098 95 AU d ) . 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,
−2
W m
NOTE The commonly used term “full disk” includes all of the Sun’s 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
−3 −2 −1
W m ; an acceptable SI submultiple unit description is W m nm . Mixed spectral solar irradiance units (e.g. quanta
−2 −1 −1 −2 −1 −1 −2 −1 −1
cm s nm , photons cm s Å and ergs cm s nm ) 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.
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ISO 21348:2007(E)
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 Earth’s atmosphere through a unit surface and at
−2
1 ua with a mean value of 1 366 W m
See Reference [7].
NOTE The solar constant, a historical term, is not constant. It varies geometrically with the Earth’s distance from the
Sun and physically with the Sun’s magnetic field activity on short to long timescales, as well as with the observer’s
−2
heliocentric latitude. The value of 1366 W m is the measurement community’s current agreement expressed through a
TSI space-based composite dataset that is normalized to an arbitrarily selected set of missions defining the SARR (see
−2
Reference [6]). A range of measured values extends from SORCE/TIM 2003-2004(+?) values (∼1 362 W m ) to
−2 −2
NIMBUS-7/HF 1978-1993 values (∼1 372 W m ), but also includes SMM/ACRIM I 1980-1989 (∼1 368 W m ),
−2 −2
ERBS/ERBE 1984-2003 (∼1 365 W m ), UARS/ACRIM II 1991-2001 (∼1 364 W m ), EURECA/SOVA2 1992-1993
−2 −2 −2
(∼1 367 W m ), SOHO/VIRGO 1996-2004(+?) (∼1 366 W m ) and ACRIMSAT/ACRIM III 2000-2004(+?) (∼1 364 W m )
measurements. The SARR reduces all solar constant space measurements to a single ensemble dataset. The currently
−2
measured 1-sigma variation in the composite dataset is approximately 0,6 W m and there is a long-term (yearly)
−2
smoothed solar cycle minimum to maximum relative variation about the mean value of approximately 1,4 W m
(see Reference [7]).
3 Symbols and abbreviated terms
λ 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.
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ISO 21348:2007(E)
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 Sun’s 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
expertise of the international solar science and material science communities was utilized in the development
of this International Standard.
4.5 Parallel activity of certification to standard
Coincident with and subsequent to the publication of this International Standard, ISO/TC 20/SC 14/WG 4
participants expect solar irradiance product providers to supply measurement sets, reference spectra, models
and solar irradiance proxies or indices that certify compliance with this International Standard (see
Reference [8]). Solar irradiance products that are compliant will be designated as such for international space
systems and materials users.
5 Solar irradiance product types
5.1 Rationale
Solar irradiance product types are established such that the suppliers and users have a common, easy-to-
recognize method of identifying standard-compliant solar irradiance products.
5.2 Type designation
A solar irradiance product can be a measurement set, reference spectrum, empirical model, first-principles
model or solar irradiance proxy/index. A solar irradiance product has the characteristics of only one type.
Type 1 is a measurement set product. Solar irradiances are measured by space- or ground-based
instrumentation (including balloons and rockets) at specified wavelengths, with an identifiable wavelength
bandpass, having a quantifiable value based upon a calibrated reference source, integrated over an identified
spatial area, and reported through a specified time interval.
Type 2 is a reference spectrum product. Reference spectra can be derived from single and/or multiple
measurement sets and can be incorporated into models. Reference spectra represent generalized
characteristics of solar irradiances for identified solar activity conditions or unique dates.
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ISO 21348:2007(E)
Type 3 is an empirical model product. An empirical solar irradiance model is derived from space- or ground-
based measurement sets (including balloons and rockets). It uses proxies to represent solar irradiances at
specified wavelengths and produces irradiances with an identifiable wavelength bandpass, having a
quantifiable value related to the measurements, integrated over an identified spatial area, and reported
through a specified time interval. A hybrid model can combine empirical methods, data assimilation or
physics-based algorithms, and is included in this type.
Type 4 is a first-principles or theoretical model product. A first-principles solar irradiance model is derived from
the fundamental physics describing energy, momentum and/or mass conservation, transfer and state changes.
It produces solar irradiances at specified wavelengths, with an identifiable wavelength bandpass, having a
quantifiable value related to the physical processes, integrated over an identified spatial area and reported
through a specified time interval.
Type 5 is a surrogate solar irradiance product, als
...