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Applied Optics

Applied Optics


  • Editor: Joseph N. Mait
  • Vol. 52, Iss. 33 — Nov. 20, 2013
  • pp: 7963–7980

Results of aperture area comparisons for exo-atmospheric total solar irradiance measurements

B. Carol Johnson, Maritoni Litorja, Joel B. Fowler, Eric L. Shirley, Robert A. Barnes, and James J. Butler  »View Author Affiliations

Applied Optics, Vol. 52, Issue 33, pp. 7963-7980 (2013)

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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.

OCIS Codes
(120.0280) Instrumentation, measurement, and metrology : Remote sensing and sensors
(120.3940) Instrumentation, measurement, and metrology : Metrology
(120.6085) Instrumentation, measurement, and metrology : Space instrumentation

ToC Category:
Instrumentation, Measurement, and Metrology

Original Manuscript: July 10, 2013
Manuscript Accepted: August 18, 2013
Published: November 13, 2013

B. Carol Johnson, Maritoni Litorja, Joel B. Fowler, Eric L. Shirley, Robert A. Barnes, and James J. Butler, "Results of aperture area comparisons for exo-atmospheric total solar irradiance measurements," Appl. Opt. 52, 7963-7980 (2013)

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