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Title: CEOS comparison of IR brightness temperature measurements in support of satellite validation. Part I: Laboratory and Ocean surface temperature comparison of radiation thermometers.

Author: Theocharous, E, Usadi, E, Fox, N P
(An asterisk (*) after an author's name indicates a non-NPL author)

Source: OP 3, July 2010
ISSN: 1754-2944

Abstract: A comparison of terrestrial based Infrared (IR) radiometric instrumentation used to support calibration and validation of satellite borne sensors with emphasis on Sea/water surface temperature was completed at NPL and at the University of Miami during April and May 2009. The objectives of the 2009 comparison were to establish the 'degree of equivalence' between terrestrially based IR Cal/Val measurements made in support of satellite observations of the Earth's surface temperature and to establish their traceability to SI units through the participation of national standards laboratories. During the 2009 comparison, NPL acted as the pilot laboratory and provided traceability to SI units during laboratory comparisons in Europe. NPL was supported by the Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami, acting as hosts and by NIST providing traceability to SI units during laboratory measurements at RSMAS. The 2009 comparison consisted of two stages in order to allow maximum participation and enable the traceability chain to be established to both NPL and NIST. Stage 1 took place at NPL in April 2009 and involved laboratory measurements of participants' blackbodies calibrated using the NPL reference transfer radiometer (AMBER), while participants' radiometers were calibrated using the NPL variable temperature blackbody. Stage 2 took place at RSMAS in May 2009 and involved laboratory measurements of participants' blackbodies calibrated using the NIST Thermal-Infrared Transfer radiometer (TXR), while participants' radiometers were calibrated using the RSMAS and NIST water bath blackbodies. Stage 2 also included the testing of the same radiometers alongside each other, completing direct day-time and night-time measurements of the surface temperature of the Ocean. This report provides the results, together with uncertainties as provided by the participants, for the comparison of the participant's radiometers, when they were monitoring the radiance temperature of the NPL variable temperature blackbody, the RSMAS water bath blackbody and NIST water bath blackbody. It also provides results of the measurement of the Ocean surface temperature completed at the University of Miami. During the 2009 comparison, all participants were encouraged to develop uncertainty budgets for all measurements they reported. All measurements reported by the participants, along with their associated uncertainties were analysed by the pilot laboratory and presented in this report.

Document Type: NPL Report

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