Abstract

Exo-atmospheric solar irradiance measurements made by the solar irradiance community since 1978 have incorporated limiting apertures with diameters measured by a number of metrology laboratories using a variety of techniques. Knowledge of the aperture area is a critical component in the conversion of radiant flux measurements to solar irradiance. A National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) sponsored international comparison of aperture area measurements of limiting apertures provided by solar irradiance researchers was performed, the effort being executed by the National Institute of Standards and Technology (NIST) in coordination with the EOS Project Science Office. Apertures that had institutional heritage with historical solar irradiance measurements were measured using the absolute aperture measurement facility at NIST. The measurement technique employed noncontact video microscopy using high-accuracy translation stages. We have quantified the differences between the participating institutions’ aperture area measurements and find no evidence to support the hypothesis that preflight aperture area measurements were the root cause of discrepancies in long-term total solar irradiance satellite measurements. Another result is the assessment of uncertainties assigned to methods used by participants. We find that uncertainties assigned to a participant’s values may be underestimated.

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2011 (2)

G. Kopp and J. L. Lean, “A new, lower value of total solar irradiance: evidence and climate significance,” Geophys. Res. Lett. 38, L01706 (2011).
[CrossRef]

C. Conscience, M. Meftah, A. Chevalier, S. Dewitte, and D. Crommelynck, “The space instrument SOVAP of the PICARD mission,” Proc. SPIE 8146, 814613 (2011).
[CrossRef]

2010 (1)

S. Mekaoui, S. Dewitte, C. Conscience, and A. Chevalier, “Total solar irradiance absolute level from DIARAD/SOVIM on the international space station,” Adv. Space Res. 45, 1393–1406 (2010).
[CrossRef]

2009 (2)

J. W. Harder, J. M. Fontenla, P. Pilewskie, E. C. Richard, and T. N. Woods, “Trends in solar spectral irradiance variability in the visible and infrared,” Geophys. Res. Lett. 36, L07801 (2009).
[CrossRef]

J. L. Lean and D. H. Rind, “How will Earth’s surface temperature change in future decades?” Geophys. Res. Lett. 36, L15708 (2009).
[CrossRef]

2008 (4)

J. J. Butler, B. C. Johnson, J. P. Rice, E. L. Shirley, and R. A. Barnes, “Sources of differences in on-orbit total solar irradiance measurements,” J. Res. Natl. Inst. Stand. Technol. 113, 187–203 (2008).
[CrossRef]

D. H. Rind, J. Lean, L. Lerner, P. Lonergan, and A. Leboissitier, “Exploring the stratospheric/tropospheric response to solar forcing,” J. Geophys. Res. 113, D24103 (2008).
[CrossRef]

J. L. Lean and D. H. Rind, “How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006,” Geophys. Res. Lett. 35, L18701 (2008).
[CrossRef]

W. Finsterle, P. Blattner, S. Moebus, I. Rüedi, C. Wehrli, M. White, and W. Schmutz, “Third comparison of the world radiometric reference and the SI radiometric scale,” Metrologia 45, 377–381 (2008).
[CrossRef]

2007 (4)

M. Litorja, B. C. Johnson, and J. B. Fowler, “Area measurements of apertures for exo-atmospheric solar irradiance for JPL,” Proc. SPIE 6677, 667708 (2007).
[CrossRef]

G. Kopp, K. Heuerman, D. Harber, and V. Drake, “The TSI radiometer facility—absolute calibrations for total solar irradiance instruments,” Proc. SPIE 6677, 667709 (2007).
[CrossRef]

J. J. Butler, B. C. Johnson, J. P. Rice, S. W. Brown, and R. A. Barnes, “Validation of radiometric standards for laboratory calibration of reflected-solar Earth observing satellite instruments,” Proc. SPIE 6677, 667707 (2007).
[CrossRef]

M. Litorja, J. B. Fowler, J. Hartmann, N. Fox, M. Stock, A. Razet, B. Khlevnoy, E. Ikonen, M. Machacs, and K. Doytchinov, “Final report on the CCPR-2 supplementary comparison of area measurements of apertures for radiometry,” Metrologia 44, 02002 (2007).
[CrossRef]

2006 (4)

J. M. Houston and J. P. Rice, “NIST reference cryogenic radiometer designed for versatile performance,” Metrologia 43, S31–S35 (2006).
[CrossRef]

G. Schmidtke, C. Fröhlich, and G. Thuillier, “ISS-SOLAR: total (TSI) and spectral (SSI) irradiance measurements,” Adv. Space Res. 37, 255–264 (2006).
[CrossRef]

C. Fröhlich, “Solar irradiance variability since 1978, revision of the PMOD composite during solar cycle 21,” Space Sci. Rev. 125, 53–65 (2006).
[CrossRef]

G. Thuillier, S. Dewitte, and W. Schmutz, “Simultaneous measurement of the total solar irradiance and solar diameter by the PICARD mission,” Adv. Space Res. 38, 1792–1806 (2006).
[CrossRef]

2004 (3)

R. B. Lee and R. S. Wilson, “Validation of spacecraft active cavity radiometer total solar irradiance (TSI): long-term measurement trends using proxy TSI least squares analyses,” Proc. SPIE 5570, 352–362 (2004).
[CrossRef]

S. Dewitte, D. Crommelynck, and A. Joukoff, “Total solar irradiance observations from DIARAD/VIRGO,” J. Geophys. Res. 109, A02102 (2004).
[CrossRef]

S. Mekaoui, S. Dewitte, D. Crommelynck, A. Chevalier, C. Conscience, and A. Joukoff, “Absolute accuracy and repeatability for the RMIB radiometers for TSI measurements,” Sol. Phys. 224, 237–246 (2004).
[CrossRef]

2003 (5)

J. J. Butler and R. A. Barnes, “The use of transfer radiometers in validating the visible through shortwave infrared calibrations of radiance sources used by instruments in NASA’s Earth Observing System,” Metrologia 40, S70–S77 (2003).
[CrossRef]

B. C. Johnson, M. Litorja, and J. J. Butler, “Preliminary results of aperture area comparison for exo-atmospheric solar irradiance,” Proc. SPIE 5151, 454–462 (2003).
[CrossRef]

G. M. Lawrence, G. Kopp, G. Rottman, J. Harder, T. Woods, and H. Loui, “Calibration of the total irradiance monitor,” Metrologia 40, S78–S80 (2003).
[CrossRef]

C. Fröhlich, “Long-term behavior of space radiometers,” Metrologia 40, S60–S65 (2003).
[CrossRef]

J. B. Fowler and M. Litorja, “Geometric area measurements of circular apertures for radiometry at NIST,” Metrologia 40, S9–S12 (2003).
[CrossRef]

2002 (1)

D. H. Rind, “The sun’s role in climate variations,” Science 296, 673–677 (2002).
[CrossRef]

2001 (3)

J. Hartmann, “Advanced comparator method for measuring ultra-small aperture areas,” Meas. Sci. Technol. 12, 1678–1682 (2001).
[CrossRef]

S. Dewitte, A. Joukoff, D. Crommelynck, R. B. Lee, R. Helizon, and R. S. Wilson, “Contribution of the Solar Constant (SOLCON) program to the long-term total solar irradiance observations,” J. Geophys. Res. 106, 15759–15765 (2001).
[CrossRef]

R. C. Willson, “The ACRIMSAT/ACRIM III experiment—extending the precision, long-term total solar irradiance climate database,” The Earth Observer 13(3), 14–17 (2001).

2000 (2)

E. A. Early, P. Y. Barnes, B. C. Johnson, J. J. Butler, C. J. Bruegge, S. F. Biggar, P. R. Spyak, and M. M. Pavlov, “Bidirectional reflectance round-robin in support of the Earth observing system program,” J. Atmos. Ocean. Technol. 17, 1077–1091 (2000).
[CrossRef]

J. J. Butler, “Calibration workshop for the total irradiance monitor (TIM) instrument on the Earth Observing System’s (EOS) solar radiation and climate experiment,” The Earth Observer 12(3), 22–25 (2000).

1999 (3)

D. Crommelynck and S. Dewitte, “Metrology of total solar irradiance monitoring,” Adv. Space Res. 24, 195–204 (1999).
[CrossRef]

R. C. Willson and R. Helizon, “EOS/ACRIM III instrumentation,” Proc. SPIE 3750, 233–242 (1999).
[CrossRef]

L. Damé, M. Hersé, G. Thuillier, T. Appourchaux, D. Crommelynck, S. Dewitte, A. Joukoff, C. Fröhlich, F. Laclare, C. Delmas, and P. Boumier, “PICARD: simultaneous measurements of the solar diameter, differential rotation, solar constant and their variations,” Adv. Space Res. 24, 205–214 (1999).
[CrossRef]

1998 (3)

J. B. Fowler, R. S. Durvasula, and A. C. Parr, “High-accuracy aperture-area measurement facilities at the National Institute of Standards and Technology,” Metrologia 35, 497–500 (1998).
[CrossRef]

J. E. Martin, N. P. Fox, N. J. Harrison, B. Shipp, and M. Anklin, “Determination and comparisons of aperture areas using geometric and radiometric techniques,” Metrologia 35, 461–464 (1998).
[CrossRef]

C. Fröhlich and J. L. Lean, “The sun’s total irradiance: cycles, trends and related climate change uncertainties since 1976,” Geophys. Res. Lett. 25, 4377–4380 (1998).
[CrossRef]

1997 (1)

J. L. Lean, “The sun’s variable radiation and its relevance for Earth,” Annu. Rev. Astron. Astrophys. 35, 33–67 (1997).
[CrossRef]

1996 (3)

J. J. Butler and B. C. Johnson, “Organization and implementation of calibration in the EOS project—part 1,” The Earth Observer 8(1), 22–27 (1996).

J. J. Butler and B. C. Johnson, “Calibration in the EOS project—part 2: implementation,” The Earth Observer 8(2), 26–31 (1996).

D. Crommelynck, A. Fichot, V. Domingo, and R. B. Lee, “SOLCON solar constant observations from the ATLAS missions,” Geophys. Res. Lett. 23, 2293–2295 (1996).
[CrossRef]

1995 (6)

D. Crommelynck, A. Fichot, R. B. Lee, and J. Romero, “First realization of the space absolute radiometric reference (SARR) during the ATLAS 2 flight period,” Adv. Space Res. 16, 17–23 (1995).
[CrossRef]

J. B. Fowler and G. Dezsi, “High-accuracy measurement of aperture area relative to standard known aperture,” J. Res. NIST 100, 277–283 (1995).

C. Fröhlich, R. Philipona, J. Romero, and C. Wehrli, “Radiometry at the Physikalisch–Meteorologisches Observatorium Davos World Radiation Centre,” Opt. Eng. 34, 2757–2766 (1995).
[CrossRef]

C. Fröhlich, J. Romero, H. Roth, C. Wehrli, B. N. Andersen, T. Appourchaux, V. Domingo, U. Telljohann, G. Berthomieu, P. Delache, J. Provost, T. Toutain, D. Crommelynck, A. Chevalier, A. Fichot, W. Däppen, D. Gough, T. Hoeksema, A. Jiménez, M. F. Gómez, J. M. Herreros, T. R. Cortés, A. R. Jones, J. M. Pap, and R. C. Willson, “VIRGO: Experiment for helioseismology and solar irradiance monitoring,” Sol. Phys. 162, 101–128 (1995).
[CrossRef]

J. Romero, C. Fröhlich, and C. Wehrli, “Solar total irradiance variability measured by SOVA-2 on board EURECA,” Adv. Space Res. 16, 29–32 (1995).
[CrossRef]

J. Romero, N. P. Fox, and C. Fröhlich, “Improved comparison of the world radiometric reference and the SI radiometric scale,” Metrologia 32, 523–524 (1995/96).
[CrossRef]

1994 (2)

J. Romero, C. Wehrli, and C. Fröhlich, “Solar total irradiance variability from SOVA 2 on board EURECA,” Sol. Phys. 152, 23–29 (1994).
[CrossRef]

D. Crommelynck, V. Domingo, B. R. Barkstrom, R. B. Lee, J. Donaldson, U. Telljohann, L. Warren, and A. Fichot, “Preliminary results of solar constant observations with the SOLCON experiment on ATLAS-1,” Adv. Space Res. 14, 253–262 (1994).
[CrossRef]

1993 (1)

D. Crommelynck, V. Domingo, A. Fichot, C. Fröhlich, B. Penelle, J. Romero, and C. Wehrli, “Preliminary results from the SOVA experiment on board the European Retrievable Carrier (EURECA),” Metrologia 30, 375–379 (1993).
[CrossRef]

1992 (1)

J. Fischer and M. Stock, “A noncontact measurement of radiometric apertures with an optical microtopography sensor,” Meas. Sci. Technol. 3, 693–698 (1992).
[CrossRef]

1991 (2)

J. Romero, N. P. Fox, and C. Fröhlich, “First comparison of the solar and an SI radiometric scale,” Metrologia 28, 125–128 (1991).
[CrossRef]

C. Fröhlich, “History of solar radiometry and the world radiometric reference,” Metrologia 28, 111–115 (1991).
[CrossRef]

1988 (1)

J. R. Hickey, B. M. Alton, H. L. Kyle, and D. Hoyt, “Total solar irradiance measurements by ERB/Nimbus 7—a review of nine years,” Space Sci. Rev. 48, 321–342 (1988).
[CrossRef]

1987 (1)

1986 (5)

B. R. Barkstrom and G. L. Smith, “The Earth radiation budget experiment: science and implementation,” Rev. Geophys. 24, 379–390 (1986).
[CrossRef]

M. R. Luther, R. B. Lee, B. R. Barkstrom, J. E. Cooper, R. D. Cess, and C. H. Duncan, “Solar calibration results from two earth radiation budget experiment nonscanner instruments,” Appl. Opt. 25, 540–545 (1986).
[CrossRef]

R. C. Willson, H. S. Hudson, C. Fröhlich, and R. W. Brusa, “Long-term downward trend in total solar irradiance,” Science 234, 1114–1117 (1986).
[CrossRef]

R. W. Brusa and C. Fröhlich, “Absolute radiometers (PMO6) and their experimental characterization,” Appl. Opt. 25, 4173–4180 (1986).
[CrossRef]

D. Crommelynck, R. W. Brusa, and V. Domingo, “Results of the solar constant experiment on board Spacelab 1,” Sol. Phys. 107, 1–9 (1986).
[CrossRef]

1985 (1)

J. E. Martin, N. P. Fox, and P. J. Key, “A cryogenic radiometer for absolute radiometric measurements,” Metrologia 21, 147–155 (1985).
[CrossRef]

1984 (4)

H. Jacobowitz, H. V. Soule, H. L. Kyle, and F. House, and Team, “Earth radiation budget (ERB) experiment: an overview,” J. Geophys. Res. 89, 5021–5038 (1984).
[CrossRef]

R. C. Willson, “Measurements of solar total irradiance and its variability,” Space Sci. Rev. 38, 203–242 (1984).
[CrossRef]

B. R. Barkstrom, “The Earth radiation budget experiment (ERBE),” Bull. Am. Meteorol. Soc. 65, 1170–1185 (1984).
[CrossRef]

D. Crommelynck and V. Domingo, “Solar irradiance observations,” Science 225, 180–181 (1984).
[CrossRef]

1981 (4)

D. Crommelynck, “The observation of the solar irradiance and its variations, challenging space metrology,” Sol. Phys. 74, 509–519 (1981).
[CrossRef]

R. C. Willson, S. Gulkis, M. Janssen, H. S. Hudson, and G. A. Chapman, “Observations of solar irradiance variability,” Science 211, 700–702 (1981).
[CrossRef]

R. C. Willson and H. S. Hudson, “Solar maximum mission experiment: Initial observations by the active cavity radiometer,” Adv. Space Res. 1, 285–288 (1981).
[CrossRef]

C. Fröhlich and R. W. Brusa, “Solar radiation and its variation over time,” Sol. Phys. 74, 209–215 (1981).
[CrossRef]

1980 (1)

1979 (1)

1976 (1)

I. Kasa, “A circle fitting procedure and its error analysis,” IEEE Trans. Instrum. Meas. IM-25, 8–14 (1976).
[CrossRef]

1974 (2)

A. Albano, “Representation of digitized contours in terms of conic arcs and straight-line segments,” Comput. Graph. Image Process. 3, 23–33 (1974).
[CrossRef]

J. R. Hickey and A. R. Karoli, “Radiometric calibrations for the Earth radiation budget experiment,” Appl. Opt. 13, 523–533 (1974).
[CrossRef]

1973 (2)

R. C. Willson, “New radiometric techniques and solar constant measurements,” Sol. Energy 14, 203–211 (1973).
[CrossRef]

R. C. Willson, “Active cavity radiometer,” Appl. Opt. 12, 810–817 (1973).
[CrossRef]

1971 (1)

R. C. Willson, “Active cavity radiometric scale, international pyroheliometric scale, and solar constant,” J. Geophys. Res. 76, 4325–4340 (1971).
[CrossRef]

Albano, A.

A. Albano, “Representation of digitized contours in terms of conic arcs and straight-line segments,” Comput. Graph. Image Process. 3, 23–33 (1974).
[CrossRef]

Alton, B. M.

J. R. Hickey, B. M. Alton, H. L. Kyle, and D. Hoyt, “Total solar irradiance measurements by ERB/Nimbus 7—a review of nine years,” Space Sci. Rev. 48, 321–342 (1988).
[CrossRef]

Andersen, B. N.

C. Fröhlich, J. Romero, H. Roth, C. Wehrli, B. N. Andersen, T. Appourchaux, V. Domingo, U. Telljohann, G. Berthomieu, P. Delache, J. Provost, T. Toutain, D. Crommelynck, A. Chevalier, A. Fichot, W. Däppen, D. Gough, T. Hoeksema, A. Jiménez, M. F. Gómez, J. M. Herreros, T. R. Cortés, A. R. Jones, J. M. Pap, and R. C. Willson, “VIRGO: Experiment for helioseismology and solar irradiance monitoring,” Sol. Phys. 162, 101–128 (1995).
[CrossRef]

Anklin, M.

J. E. Martin, N. P. Fox, N. J. Harrison, B. Shipp, and M. Anklin, “Determination and comparisons of aperture areas using geometric and radiometric techniques,” Metrologia 35, 461–464 (1998).
[CrossRef]

M. Anklin, C. Wehrli, C. Fröhlich, and F. Pepe, “Total solar and spectral irradiance measured in France during a stratospheric balloon flight,” in Fourteenth ESA Symposium on European Rocket and Balloon Programs and Related Research, ESA SP-437, B. Kaldeich-Schürmann, ed. (European Space Agency, 1999), pp. 537–540.

Appourchaux, T.

L. Damé, M. Hersé, G. Thuillier, T. Appourchaux, D. Crommelynck, S. Dewitte, A. Joukoff, C. Fröhlich, F. Laclare, C. Delmas, and P. Boumier, “PICARD: simultaneous measurements of the solar diameter, differential rotation, solar constant and their variations,” Adv. Space Res. 24, 205–214 (1999).
[CrossRef]

C. Fröhlich, J. Romero, H. Roth, C. Wehrli, B. N. Andersen, T. Appourchaux, V. Domingo, U. Telljohann, G. Berthomieu, P. Delache, J. Provost, T. Toutain, D. Crommelynck, A. Chevalier, A. Fichot, W. Däppen, D. Gough, T. Hoeksema, A. Jiménez, M. F. Gómez, J. M. Herreros, T. R. Cortés, A. R. Jones, J. M. Pap, and R. C. Willson, “VIRGO: Experiment for helioseismology and solar irradiance monitoring,” Sol. Phys. 162, 101–128 (1995).
[CrossRef]

Barkstrom, B. R.

D. Crommelynck, V. Domingo, B. R. Barkstrom, R. B. Lee, J. Donaldson, U. Telljohann, L. Warren, and A. Fichot, “Preliminary results of solar constant observations with the SOLCON experiment on ATLAS-1,” Adv. Space Res. 14, 253–262 (1994).
[CrossRef]

R. B. Lee, B. R. Barkstrom, and R. D. Cess, “Characteristics of the Earth radiation budget experiment solar monitors,” Appl. Opt. 26, 3090–3096 (1987).
[CrossRef]

B. R. Barkstrom and G. L. Smith, “The Earth radiation budget experiment: science and implementation,” Rev. Geophys. 24, 379–390 (1986).
[CrossRef]

M. R. Luther, R. B. Lee, B. R. Barkstrom, J. E. Cooper, R. D. Cess, and C. H. Duncan, “Solar calibration results from two earth radiation budget experiment nonscanner instruments,” Appl. Opt. 25, 540–545 (1986).
[CrossRef]

B. R. Barkstrom, “The Earth radiation budget experiment (ERBE),” Bull. Am. Meteorol. Soc. 65, 1170–1185 (1984).
[CrossRef]

Barnes, P. Y.

E. A. Early, P. Y. Barnes, B. C. Johnson, J. J. Butler, C. J. Bruegge, S. F. Biggar, P. R. Spyak, and M. M. Pavlov, “Bidirectional reflectance round-robin in support of the Earth observing system program,” J. Atmos. Ocean. Technol. 17, 1077–1091 (2000).
[CrossRef]

Barnes, R. A.

J. J. Butler, B. C. Johnson, J. P. Rice, E. L. Shirley, and R. A. Barnes, “Sources of differences in on-orbit total solar irradiance measurements,” J. Res. Natl. Inst. Stand. Technol. 113, 187–203 (2008).
[CrossRef]

J. J. Butler, B. C. Johnson, J. P. Rice, S. W. Brown, and R. A. Barnes, “Validation of radiometric standards for laboratory calibration of reflected-solar Earth observing satellite instruments,” Proc. SPIE 6677, 667707 (2007).
[CrossRef]

J. J. Butler and R. A. Barnes, “The use of transfer radiometers in validating the visible through shortwave infrared calibrations of radiance sources used by instruments in NASA’s Earth Observing System,” Metrologia 40, S70–S77 (2003).
[CrossRef]

Berthomieu, G.

C. Fröhlich, J. Romero, H. Roth, C. Wehrli, B. N. Andersen, T. Appourchaux, V. Domingo, U. Telljohann, G. Berthomieu, P. Delache, J. Provost, T. Toutain, D. Crommelynck, A. Chevalier, A. Fichot, W. Däppen, D. Gough, T. Hoeksema, A. Jiménez, M. F. Gómez, J. M. Herreros, T. R. Cortés, A. R. Jones, J. M. Pap, and R. C. Willson, “VIRGO: Experiment for helioseismology and solar irradiance monitoring,” Sol. Phys. 162, 101–128 (1995).
[CrossRef]

Biggar, S. F.

E. A. Early, P. Y. Barnes, B. C. Johnson, J. J. Butler, C. J. Bruegge, S. F. Biggar, P. R. Spyak, and M. M. Pavlov, “Bidirectional reflectance round-robin in support of the Earth observing system program,” J. Atmos. Ocean. Technol. 17, 1077–1091 (2000).
[CrossRef]

Blattner, P.

W. Finsterle, P. Blattner, S. Moebus, I. Rüedi, C. Wehrli, M. White, and W. Schmutz, “Third comparison of the world radiometric reference and the SI radiometric scale,” Metrologia 45, 377–381 (2008).
[CrossRef]

Boumier, P.

L. Damé, M. Hersé, G. Thuillier, T. Appourchaux, D. Crommelynck, S. Dewitte, A. Joukoff, C. Fröhlich, F. Laclare, C. Delmas, and P. Boumier, “PICARD: simultaneous measurements of the solar diameter, differential rotation, solar constant and their variations,” Adv. Space Res. 24, 205–214 (1999).
[CrossRef]

Brown, S. W.

J. J. Butler, B. C. Johnson, J. P. Rice, S. W. Brown, and R. A. Barnes, “Validation of radiometric standards for laboratory calibration of reflected-solar Earth observing satellite instruments,” Proc. SPIE 6677, 667707 (2007).
[CrossRef]

Bruegge, C. J.

E. A. Early, P. Y. Barnes, B. C. Johnson, J. J. Butler, C. J. Bruegge, S. F. Biggar, P. R. Spyak, and M. M. Pavlov, “Bidirectional reflectance round-robin in support of the Earth observing system program,” J. Atmos. Ocean. Technol. 17, 1077–1091 (2000).
[CrossRef]

Brusa, R. W.

D. Crommelynck, R. W. Brusa, and V. Domingo, “Results of the solar constant experiment on board Spacelab 1,” Sol. Phys. 107, 1–9 (1986).
[CrossRef]

R. W. Brusa and C. Fröhlich, “Absolute radiometers (PMO6) and their experimental characterization,” Appl. Opt. 25, 4173–4180 (1986).
[CrossRef]

R. C. Willson, H. S. Hudson, C. Fröhlich, and R. W. Brusa, “Long-term downward trend in total solar irradiance,” Science 234, 1114–1117 (1986).
[CrossRef]

C. Fröhlich and R. W. Brusa, “Solar radiation and its variation over time,” Sol. Phys. 74, 209–215 (1981).
[CrossRef]

Butler, J. J.

J. J. Butler, B. C. Johnson, J. P. Rice, E. L. Shirley, and R. A. Barnes, “Sources of differences in on-orbit total solar irradiance measurements,” J. Res. Natl. Inst. Stand. Technol. 113, 187–203 (2008).
[CrossRef]

J. J. Butler, B. C. Johnson, J. P. Rice, S. W. Brown, and R. A. Barnes, “Validation of radiometric standards for laboratory calibration of reflected-solar Earth observing satellite instruments,” Proc. SPIE 6677, 667707 (2007).
[CrossRef]

J. J. Butler and R. A. Barnes, “The use of transfer radiometers in validating the visible through shortwave infrared calibrations of radiance sources used by instruments in NASA’s Earth Observing System,” Metrologia 40, S70–S77 (2003).
[CrossRef]

B. C. Johnson, M. Litorja, and J. J. Butler, “Preliminary results of aperture area comparison for exo-atmospheric solar irradiance,” Proc. SPIE 5151, 454–462 (2003).
[CrossRef]

E. A. Early, P. Y. Barnes, B. C. Johnson, J. J. Butler, C. J. Bruegge, S. F. Biggar, P. R. Spyak, and M. M. Pavlov, “Bidirectional reflectance round-robin in support of the Earth observing system program,” J. Atmos. Ocean. Technol. 17, 1077–1091 (2000).
[CrossRef]

J. J. Butler, “Calibration workshop for the total irradiance monitor (TIM) instrument on the Earth Observing System’s (EOS) solar radiation and climate experiment,” The Earth Observer 12(3), 22–25 (2000).

J. J. Butler and B. C. Johnson, “Organization and implementation of calibration in the EOS project—part 1,” The Earth Observer 8(1), 22–27 (1996).

J. J. Butler and B. C. Johnson, “Calibration in the EOS project—part 2: implementation,” The Earth Observer 8(2), 26–31 (1996).

Cess, R. D.

Chapman, G. A.

R. C. Willson, S. Gulkis, M. Janssen, H. S. Hudson, and G. A. Chapman, “Observations of solar irradiance variability,” Science 211, 700–702 (1981).
[CrossRef]

Chevalier, A.

C. Conscience, M. Meftah, A. Chevalier, S. Dewitte, and D. Crommelynck, “The space instrument SOVAP of the PICARD mission,” Proc. SPIE 8146, 814613 (2011).
[CrossRef]

S. Mekaoui, S. Dewitte, C. Conscience, and A. Chevalier, “Total solar irradiance absolute level from DIARAD/SOVIM on the international space station,” Adv. Space Res. 45, 1393–1406 (2010).
[CrossRef]

S. Mekaoui, S. Dewitte, D. Crommelynck, A. Chevalier, C. Conscience, and A. Joukoff, “Absolute accuracy and repeatability for the RMIB radiometers for TSI measurements,” Sol. Phys. 224, 237–246 (2004).
[CrossRef]

C. Fröhlich, J. Romero, H. Roth, C. Wehrli, B. N. Andersen, T. Appourchaux, V. Domingo, U. Telljohann, G. Berthomieu, P. Delache, J. Provost, T. Toutain, D. Crommelynck, A. Chevalier, A. Fichot, W. Däppen, D. Gough, T. Hoeksema, A. Jiménez, M. F. Gómez, J. M. Herreros, T. R. Cortés, A. R. Jones, J. M. Pap, and R. C. Willson, “VIRGO: Experiment for helioseismology and solar irradiance monitoring,” Sol. Phys. 162, 101–128 (1995).
[CrossRef]

Conscience, C.

C. Conscience, M. Meftah, A. Chevalier, S. Dewitte, and D. Crommelynck, “The space instrument SOVAP of the PICARD mission,” Proc. SPIE 8146, 814613 (2011).
[CrossRef]

S. Mekaoui, S. Dewitte, C. Conscience, and A. Chevalier, “Total solar irradiance absolute level from DIARAD/SOVIM on the international space station,” Adv. Space Res. 45, 1393–1406 (2010).
[CrossRef]

S. Mekaoui, S. Dewitte, D. Crommelynck, A. Chevalier, C. Conscience, and A. Joukoff, “Absolute accuracy and repeatability for the RMIB radiometers for TSI measurements,” Sol. Phys. 224, 237–246 (2004).
[CrossRef]

Cooper, J. E.

Cortés, T. R.

C. Fröhlich, J. Romero, H. Roth, C. Wehrli, B. N. Andersen, T. Appourchaux, V. Domingo, U. Telljohann, G. Berthomieu, P. Delache, J. Provost, T. Toutain, D. Crommelynck, A. Chevalier, A. Fichot, W. Däppen, D. Gough, T. Hoeksema, A. Jiménez, M. F. Gómez, J. M. Herreros, T. R. Cortés, A. R. Jones, J. M. Pap, and R. C. Willson, “VIRGO: Experiment for helioseismology and solar irradiance monitoring,” Sol. Phys. 162, 101–128 (1995).
[CrossRef]

Crommelynck, D.

C. Conscience, M. Meftah, A. Chevalier, S. Dewitte, and D. Crommelynck, “The space instrument SOVAP of the PICARD mission,” Proc. SPIE 8146, 814613 (2011).
[CrossRef]

S. Mekaoui, S. Dewitte, D. Crommelynck, A. Chevalier, C. Conscience, and A. Joukoff, “Absolute accuracy and repeatability for the RMIB radiometers for TSI measurements,” Sol. Phys. 224, 237–246 (2004).
[CrossRef]

S. Dewitte, D. Crommelynck, and A. Joukoff, “Total solar irradiance observations from DIARAD/VIRGO,” J. Geophys. Res. 109, A02102 (2004).
[CrossRef]

S. Dewitte, A. Joukoff, D. Crommelynck, R. B. Lee, R. Helizon, and R. S. Wilson, “Contribution of the Solar Constant (SOLCON) program to the long-term total solar irradiance observations,” J. Geophys. Res. 106, 15759–15765 (2001).
[CrossRef]

D. Crommelynck and S. Dewitte, “Metrology of total solar irradiance monitoring,” Adv. Space Res. 24, 195–204 (1999).
[CrossRef]

L. Damé, M. Hersé, G. Thuillier, T. Appourchaux, D. Crommelynck, S. Dewitte, A. Joukoff, C. Fröhlich, F. Laclare, C. Delmas, and P. Boumier, “PICARD: simultaneous measurements of the solar diameter, differential rotation, solar constant and their variations,” Adv. Space Res. 24, 205–214 (1999).
[CrossRef]

D. Crommelynck, A. Fichot, V. Domingo, and R. B. Lee, “SOLCON solar constant observations from the ATLAS missions,” Geophys. Res. Lett. 23, 2293–2295 (1996).
[CrossRef]

D. Crommelynck, A. Fichot, R. B. Lee, and J. Romero, “First realization of the space absolute radiometric reference (SARR) during the ATLAS 2 flight period,” Adv. Space Res. 16, 17–23 (1995).
[CrossRef]

C. Fröhlich, J. Romero, H. Roth, C. Wehrli, B. N. Andersen, T. Appourchaux, V. Domingo, U. Telljohann, G. Berthomieu, P. Delache, J. Provost, T. Toutain, D. Crommelynck, A. Chevalier, A. Fichot, W. Däppen, D. Gough, T. Hoeksema, A. Jiménez, M. F. Gómez, J. M. Herreros, T. R. Cortés, A. R. Jones, J. M. Pap, and R. C. Willson, “VIRGO: Experiment for helioseismology and solar irradiance monitoring,” Sol. Phys. 162, 101–128 (1995).
[CrossRef]

D. Crommelynck, V. Domingo, B. R. Barkstrom, R. B. Lee, J. Donaldson, U. Telljohann, L. Warren, and A. Fichot, “Preliminary results of solar constant observations with the SOLCON experiment on ATLAS-1,” Adv. Space Res. 14, 253–262 (1994).
[CrossRef]

D. Crommelynck, V. Domingo, A. Fichot, C. Fröhlich, B. Penelle, J. Romero, and C. Wehrli, “Preliminary results from the SOVA experiment on board the European Retrievable Carrier (EURECA),” Metrologia 30, 375–379 (1993).
[CrossRef]

D. Crommelynck, R. W. Brusa, and V. Domingo, “Results of the solar constant experiment on board Spacelab 1,” Sol. Phys. 107, 1–9 (1986).
[CrossRef]

D. Crommelynck and V. Domingo, “Solar irradiance observations,” Science 225, 180–181 (1984).
[CrossRef]

D. Crommelynck, “The observation of the solar irradiance and its variations, challenging space metrology,” Sol. Phys. 74, 509–519 (1981).
[CrossRef]

D. Crommelynck, “Fundamentals of absolute pyroheliometry and objective characterization,” in Langley Research Center Earth Radiation Science Seminars, NASA CP 2239, J. B. Hall, ed. (NASA LaRC, 1982), pp. 53–88.

D. Crommelynck, V. Domingo, A. Fichot, and R. B. Lee, “Total solar irradiance observations from the EURECA and ATLAS missions,” in The Sun as a Variable Star: Solar and Stellar Irradiance Variations, J. M. Pap, C. Fröhlich, H. S. Hudson, and S. K. Solanski, eds. (Cambridge University, 1994), pp. 63–69.

D. Crommelynck, “Factors limiting the accuracy of absolute radiometry,” in New Developments and Applications in Optical Radiometry, N. P. Fox and D. H. Nettleton, eds., Vol. 92 of Institute of Physics Conference Series (Institute of Physics, 1989), pp. 19–25.

L. Damé, D. Cugnet, M. Hersé, D. Crommelynck, S. Dewitte, A. Joukoff, I. Ruedi, W. Schmutz, C. Wehrli, C. Delmas, F. Laclare, and J.-P. Rozelot, “PICARD: Solar diameter, irradiance and climate,” in The Solar Cycle and Terrestrial Climate, Proceedings of the 1st Solar and Space Weather Euroconference, A. Wilson, ed. (European Space Agency, 2000).

Cugnet, D.

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B. R. Barkstrom and G. L. Smith, “The Earth radiation budget experiment: science and implementation,” Rev. Geophys. 24, 379–390 (1986).
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J. R. Hickey, B. M. Alton, H. L. Kyle, and D. Hoyt, “Total solar irradiance measurements by ERB/Nimbus 7—a review of nine years,” Space Sci. Rev. 48, 321–342 (1988).
[CrossRef]

R. C. Willson, “Measurements of solar total irradiance and its variability,” Space Sci. Rev. 38, 203–242 (1984).
[CrossRef]

The Earth Observer (4)

R. C. Willson, “The ACRIMSAT/ACRIM III experiment—extending the precision, long-term total solar irradiance climate database,” The Earth Observer 13(3), 14–17 (2001).

J. J. Butler, “Calibration workshop for the total irradiance monitor (TIM) instrument on the Earth Observing System’s (EOS) solar radiation and climate experiment,” The Earth Observer 12(3), 22–25 (2000).

J. J. Butler and B. C. Johnson, “Organization and implementation of calibration in the EOS project—part 1,” The Earth Observer 8(1), 22–27 (1996).

J. J. Butler and B. C. Johnson, “Calibration in the EOS project—part 2: implementation,” The Earth Observer 8(2), 26–31 (1996).

Other (21)

G. B. Ohring, Achieving Satellite Instrument Calibration for Climate Change (ASIC3), Center for Satellite Applications and Research (NESDIS/NOAA, U.S. Dept. of Commerce, 2008).

G. Kopp, “Total Solar Irradiance Database” (2013), retrieved http://spot.colorado.edu/~koppg/TSI/TSI.jpg .

F. Hengstberger, Absolute Radiometry: Electrically Calibrated Thermal Detectors of Optical Radiation (Academic, 1989).

R. Goebel, M. Stock, and R. Köhler, “Report on the international comparison of cryogenic radiometers based on transfer detectors, , September 2000” (Paris, France, 2000).

D. Crommelynck, “Fundamentals of absolute pyroheliometry and objective characterization,” in Langley Research Center Earth Radiation Science Seminars, NASA CP 2239, J. B. Hall, ed. (NASA LaRC, 1982), pp. 53–88.

J. B. Fowler, National Institute of Standards and Technology (personal communication, 2000).

T. M. Goodman, J. E. Martin, B. D. Shipp, and N. P. Turner, “The manufacture and measurement of precision apertures,” in New Developments and Applications in Optical Radiometry, N. P. Fox and D. H. Netttleton, eds., Vol. 92 of Institute of Physics Conference Series (Institute of Physics, 1989), pp. 121–128.

Roundness, a measure of radial deviations, is defined as the difference in radii of the two coplanar concentric circles that just include the profile of the surface.

H. Jacobowitz, L. L. Stowe, and J. R. Hickey, “The Earth radiation budget (ERB) experiment,” in The Nimbus 7 Users’ Guide, C. R. Madrid, ed. (NASA GSFC, 1978), pp. 33–70.

C. Fröhlich and W. Finsterle, “Total solar irradiance from VIRGO on SOHO,” in The Solar Cycle and Terrestrial Climate, Proceedings of the 1st Solar and Space Weather Euroconference, ESA SP-463, A. Wilson, ed. (European Space Agency, 2000), pp. 665–670.

G. Thuillier, C. Fröhlich, and G. Schmidtke, “Spectral and total solar irradiance measurements on board the international space station,” in Proceedings of the 2nd European Symposium on the Utilisation of the International Space Station, ESA SP-433 (European Space Agency, 1999), pp. 605–611.

M. Anklin, C. Wehrli, C. Fröhlich, and F. Pepe, “Total solar and spectral irradiance measured in France during a stratospheric balloon flight,” in Fourteenth ESA Symposium on European Rocket and Balloon Programs and Related Research, ESA SP-437, B. Kaldeich-Schürmann, ed. (European Space Agency, 1999), pp. 537–540.

D. Crommelynck, “Factors limiting the accuracy of absolute radiometry,” in New Developments and Applications in Optical Radiometry, N. P. Fox and D. H. Nettleton, eds., Vol. 92 of Institute of Physics Conference Series (Institute of Physics, 1989), pp. 19–25.

L. Damé, D. Cugnet, M. Hersé, D. Crommelynck, S. Dewitte, A. Joukoff, I. Ruedi, W. Schmutz, C. Wehrli, C. Delmas, F. Laclare, and J.-P. Rozelot, “PICARD: Solar diameter, irradiance and climate,” in The Solar Cycle and Terrestrial Climate, Proceedings of the 1st Solar and Space Weather Euroconference, A. Wilson, ed. (European Space Agency, 2000).

D. Crommelynck, V. Domingo, A. Fichot, and R. B. Lee, “Total solar irradiance observations from the EURECA and ATLAS missions,” in The Sun as a Variable Star: Solar and Stellar Irradiance Variations, J. M. Pap, C. Fröhlich, H. S. Hudson, and S. K. Solanski, eds. (Cambridge University, 1994), pp. 63–69.

R. C. Willson, “Irradiance observations of SMM, Spacelab 1, UARS, and ATLAS missions,” in The Sun as a Variable Star. Solar and Stellar Irradiance Variations, J. M. Pap, C. Fröhlich, H. S. Hudson, and S. K. Solanski, eds. (Cambridge University, 1994), pp. 54–62.

Type A uncertainty components are those evaluated using statistical analysis.

B. Efron and R. Tibshirani, An Introduction to the Bootstrap, Monographs on Statistics and Applied Probability (Chapman and Hall, 1993).

Evaluation of Measurement Data—Guide to the Expression of Uncertainty in Measurement, (Bureau International des Poids et Mesures, Paris, France, 2008).

An uncertainty for an 8 mm diameter aperture was stated to be equal to u(d) at k=2 plus twice the departure from roundness.

W. Finsterle, Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center (personal communication, 2013).

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Figures (7)

Fig. 1.
Fig. 1.

TSI measurements made since 1978 along with the monthly sunspot number as of 30 August 2013 [8].

Fig. 2.
Fig. 2.

Schematic of a DIARAD/VIRGO aperture with 8 mm inner diameter, 28 mm outer diameter, thickness of 4 mm, spherical front surface, spherical bevel, and 0.1 mm land. The RMIB comparison apertures with the exception of #5 and #8.5 were similar in design, but with different nominal inner and outer diameters and overall thicknesses.

Fig. 3.
Fig. 3.

Schematic of PMOD/WRC apertures PMO609, PMO611, SOVA R 111, and SOVA R 113. The nominal inner diameter is 5 mm, the outer diameter is 25 mm, the thickness is 2 mm, the land is 0.02 mm, and the bevel is at 45°.

Fig. 4.
Fig. 4.

Schematic of the LaRC aperture type A, C, and D used for ERBE. The nominal inner diameter is 8 mm, the outer diameter is 48.5 mm, the thickness is 8.1 mm, and the land, which exists, was not specified. The bevel is at 45°.

Fig. 5.
Fig. 5.

Schematic of the ACR type apertures used for ACRIM. The aperture is at the end of a baffle tube assembly that mounts to the cavity. The nominal inner diameter is 8 mm, the outer diameter at the aperture is 24.08 mm, the total length is 47 mm, and the bevel is at 41°.

Fig. 6.
Fig. 6.

Photographs of the NIST aperture measurement facility. Air bearings and a wavelength-compensated laser interferometer with nested XY stages move the aperture into the FOV of the CCD-based microscope that is mounted on the Z stage. The laboratory is optimized for thermal and vibrational stability.

Fig. 7.
Fig. 7.

Results of the aperture area comparison shown as the ratio of the participant area normalized by the NIST area. The vertical lines are the k=2 uncertainty in these ratios. RMIB and PMOD/WRC are plotted using the left ordinate; LaRC and JPL are plotted using the right ordinate.

Tables (9)

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Table 1. Long-Term TSI Satellite Instruments and Associated Data Records from 1978 to the Present and Near Futurea

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Table 2. Apertures Submitted by the Institutions, with the Comparison Designation, the Institution and its Designation, the Material, Nominal Value of d, and the Source and Date of the Submitted Aperture Values and Uncertainties

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Table 3. Uncertainty Components for the RMIB Aperturesa

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Table 4. Uncertainty Components for the RMIB Aperturesa

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Table 5. Uncertainty Components for the PMOD/WRC Aperturesa

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Table 6. Uncertainty Components for the LaRC Aperturesa

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Table 7. Uncertainty Components for the JPL Aperturesa

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Table 8. Values for the Coefficient of Linear Expansion Used to Correct the NIST Measurement Results to 20°Ca

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Table 9. NIST Measurement Results of Apertures and the Results Submitted by the Institutionsa

Equations (3)

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Cx=pLxcosβMandCy=pLysinβM.
xi=XS±Cxandyi=YS±Cy.
rj(20°C)=[(20°CTj)α+1]r(Tj),

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