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Proceedings Paper

Remeasuring the extraterrestrial solar spectral irradiance
Author(s): Lee Harrison; Jerry L. Berndt; Piotr W. Kiedron
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Paper Abstract

We will measure the solar spectral irradiance by deploying a CCD-array solar spectrograph to a high altitude favorable site, as part of a self-contained autonomous system with a calibration system using a monochromator and absolute photodiode "trap detectors." Data will be reduced using Langley extrapolation (and in the stronger absorption bands methods similar to Reagan-Brugge fitting), to yield the solar output free of atmospheric absorption. This measurement system will substantially improve the accuracy of the field measurements by making the instrument continuously self-calibrating against a local absolute standard in the range 400 - 900 nm. In the ranges 360 - 400 nm and also 900 - 1100 the trap detectors are not an absolute standard, but serve as a very reproducible transfer standard from an irradiance scale to be taken from either NIST lamps, or more recently-introduced detectors with calibrated efficiencies. We expect an absolute accuracy of 0.3% for solar-spectrum determination in the range 400 to 900 nm, not including the O2 band at 760 nm, and the H2O bands at 820 and 940 nm. In the 360 - 400 nm domain we may be able to extend trap-detector quantum efficiency to allow an accuracy better than a secondary irradiance transfer, otherwise this domain and the range 900 to 1100 nm will have an accuracy of ≈ 1 %. The extrapolations in the strong-absorption bands will have an increased uncertainty which can be estimated from the statistics of the data. We describe the instrument and self-calibration methadologies and design.

Paper Details

Date Published: 3 November 2003
PDF: 6 pages
Proc. SPIE 5157, Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research V, (3 November 2003); doi: 10.1117/12.506149
Show Author Affiliations
Lee Harrison, Univ. at Albany (United States)
Jerry L. Berndt, Univ. at Albany (United States)
Piotr W. Kiedron, Univ. at Albany (United States)

Published in SPIE Proceedings Vol. 5157:
Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research V
Allen M. Larar; Joseph A. Shaw; Zhaobo Sun, Editor(s)

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