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The calibration and intercalibration of sea-going infrared radiometer systems using a low cost blackbody cavity

The calibration and intercalibration of sea-going infrared radiometer systems using a low cost blackbody cavity
The calibration and intercalibration of sea-going infrared radiometer systems using a low cost blackbody cavity
There are many infrared radiometer systems available for the measurement of in situ sea surface skin temperature (SSST). Unfortunately, the marine environment is extremely hostile to optical components, and to ensure the accuracy of SSST measurements, an absolute calibration of instrumentation using an independent calibration reference is required both before and after any sea deployment. During extended deployments it is prudent to have additional regular calibration data to monitor instrument performance characteristics. This paper presents a design for an ambient temperature (278–325 K), wide aperture (100 mm), reference blackbody unit that may be used to calibrate a variety of sea-going infrared radiometer systems both in the laboratory and in the field. The blackbody consists of a spun copper cavity coated with well-characterized high emissivity paint (Mankiewicz Nextel Velvet Coating 811-21) immersed in a water bath that is continuously mixed using a strong water pump. The radiant temperature of the blackbody cavity is determined from the measured water bath temperature. Results derived from validation and intercomparison experiments show this blackbody design to be an accurate and reliable reference blackbody source. However, in order to ensure that the best possible calibration data are obtained, extreme care must be taken to ensure the accurate measurement of the water bath temperature, proper positioning of a radiometer in front of the cavity itself, and prevention of condensation on the cavity surface. Four blackbody units have been specifically built for the European Union combined action for the study of the ocean thermal skin (CASOTS) program. Using these units as reference radiance sources, the authors describe the strategy adopted and present results obtained from the CASOTS radiometer intercalibration experiment. These results highlight the need to obtain independent calibration data both before and after sea-going radiometer deployments and the need to standardize field radiometer calibration protocols.
0739-0572
1183–1197
Donlon, C.J.
9324225c-a1a7-4302-a3c2-f5679fa4ef45
Nightingale, T.
c5341aa6-1784-4d85-ad41-e17655963671
L., Fiedler
ca99d4d8-74b8-4f0a-a481-4a020f1e64e7
Fisher, Gary
5583221a-f6e9-42e1-964a-c51facc6219f
Baldwin, D.
58d543fc-7485-43a2-bd50-59b00a881a1a
Robinson, I.S.
548399f7-f9eb-41ea-a28d-a248d3011edc
Donlon, C.J.
9324225c-a1a7-4302-a3c2-f5679fa4ef45
Nightingale, T.
c5341aa6-1784-4d85-ad41-e17655963671
L., Fiedler
ca99d4d8-74b8-4f0a-a481-4a020f1e64e7
Fisher, Gary
5583221a-f6e9-42e1-964a-c51facc6219f
Baldwin, D.
58d543fc-7485-43a2-bd50-59b00a881a1a
Robinson, I.S.
548399f7-f9eb-41ea-a28d-a248d3011edc

Donlon, C.J., Nightingale, T., L., Fiedler, Fisher, Gary, Baldwin, D. and Robinson, I.S. (1999) The calibration and intercalibration of sea-going infrared radiometer systems using a low cost blackbody cavity. Journal of Atmospheric and Oceanic Technology, 16 (9), 1183–1197. (doi:10.1175/1520-0426(1999)016<1183:TCAIOS>2.0.CO;2).

Record type: Article

Abstract

There are many infrared radiometer systems available for the measurement of in situ sea surface skin temperature (SSST). Unfortunately, the marine environment is extremely hostile to optical components, and to ensure the accuracy of SSST measurements, an absolute calibration of instrumentation using an independent calibration reference is required both before and after any sea deployment. During extended deployments it is prudent to have additional regular calibration data to monitor instrument performance characteristics. This paper presents a design for an ambient temperature (278–325 K), wide aperture (100 mm), reference blackbody unit that may be used to calibrate a variety of sea-going infrared radiometer systems both in the laboratory and in the field. The blackbody consists of a spun copper cavity coated with well-characterized high emissivity paint (Mankiewicz Nextel Velvet Coating 811-21) immersed in a water bath that is continuously mixed using a strong water pump. The radiant temperature of the blackbody cavity is determined from the measured water bath temperature. Results derived from validation and intercomparison experiments show this blackbody design to be an accurate and reliable reference blackbody source. However, in order to ensure that the best possible calibration data are obtained, extreme care must be taken to ensure the accurate measurement of the water bath temperature, proper positioning of a radiometer in front of the cavity itself, and prevention of condensation on the cavity surface. Four blackbody units have been specifically built for the European Union combined action for the study of the ocean thermal skin (CASOTS) program. Using these units as reference radiance sources, the authors describe the strategy adopted and present results obtained from the CASOTS radiometer intercalibration experiment. These results highlight the need to obtain independent calibration data both before and after sea-going radiometer deployments and the need to standardize field radiometer calibration protocols.

Text
1520-0426(1999)016_1183_TCAIOS_2.0.CO;2
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Published date: 1 September 1999
Organisations: Ocean and Earth Science, Ocean & Earth Science Technical

Identifiers

Local EPrints ID: 406405
URI: http://eprints.soton.ac.uk/id/eprint/406405
ISSN: 0739-0572
PURE UUID: 0cda2453-6833-4456-853c-a33d05ead675

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Date deposited: 10 Mar 2017 10:46
Last modified: 02 Dec 2019 19:20

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