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An infrared sea surface temperature autonomous radiometer (ISAR) for deployment aboard Volunteer Observing Ships (VOS)

An infrared sea surface temperature autonomous radiometer (ISAR) for deployment aboard Volunteer Observing Ships (VOS)
An infrared sea surface temperature autonomous radiometer (ISAR) for deployment aboard Volunteer Observing Ships (VOS)
The infrared SST autonomous radiometer (ISAR) is a self-calibrating instrument capable of measuring in situ sea surface skin temperature (SSTskin) to an accuracy of 0.1 K. Extensive field deployments alongside two independent research radiometers measuring SSTskin using different spectral and geometric configurations show that, relatively, ISAR SSTskin has a zero bias ±0.14 K rms. The ISAR instrument has been developed for satellite SST validation and other scientific programs. The ISAR can be deployed continuously on voluntary observing ships (VOS) without any service requirement or operator intervention for periods of up to 3 months. Five ISAR instruments have been built and are in sustained use in the United States, China, and Europe. This paper describes the ISAR instrument including the special design features that enabled a single channel radiometer with a spectral bandpass of 9.6–11.5 ?m to be adapted for autonomous use. The entire instrument infrared optical path is calibrated by viewing two blackbody reference cavities at different temperatures to maintain high accuracy while tolerating moderate contamination of optical components by salt deposition. During bad weather, an innovative storm shutter, triggered by a sensitive optical rain gauge, automatically seals the instrument from the external environment. Data are presented that verify the instrument calibration and functionality in such situations. A watchdog timer and auto-reboot function support automatic data logging recovery in case of power outages typically encountered on ships. An RS485 external port allows supporting instruments that are not part of the core ISAR package (e.g., a solarimeter) to be logged using the ISAR system. All data are processed by the ISAR instrument and are relayed to a host computer via the RS232 serial link as (National Electronics Manufacturers Association) NEMA-style strings allowing easy integration into many commercial onboard scientific data logging systems. In case of a communications failure, data are stored on board using a CompactFlash card that can be retrieved when the instrument is serviced. The success of the design is demonstrated using results obtained over 21 months in the English Channel and Bay of Biscay as part of a campaign to validate SSTskin observations derived from the Environmental Satellite (Envisat) Advanced Along-Track Scanning Radiometer (AATSR).

0739-0572
93-113
Donlon, C.
a01bc388-2922-4e4e-b54c-108b3ad5f0e2
Robinson, I.S.
548399f7-f9eb-41ea-a28d-a248d3011edc
Reynolds, M.
240b47f0-77d7-43c8-947f-dcc0518f8608
Wimmer, W.
7b66c35e-5f83-4f95-82e3-5ced9614f28d
Fisher, G.
5583221a-f6e9-42e1-964a-c51facc6219f
Edwards, R.
93648ffb-c74d-4c6c-8851-3419c2a16f9d
Nightingale, T.J.
cac522f6-c705-4080-9d7d-a1d1d6a3a8ab
Donlon, C.
a01bc388-2922-4e4e-b54c-108b3ad5f0e2
Robinson, I.S.
548399f7-f9eb-41ea-a28d-a248d3011edc
Reynolds, M.
240b47f0-77d7-43c8-947f-dcc0518f8608
Wimmer, W.
7b66c35e-5f83-4f95-82e3-5ced9614f28d
Fisher, G.
5583221a-f6e9-42e1-964a-c51facc6219f
Edwards, R.
93648ffb-c74d-4c6c-8851-3419c2a16f9d
Nightingale, T.J.
cac522f6-c705-4080-9d7d-a1d1d6a3a8ab

Donlon, C., Robinson, I.S., Reynolds, M., Wimmer, W., Fisher, G., Edwards, R. and Nightingale, T.J. (2008) An infrared sea surface temperature autonomous radiometer (ISAR) for deployment aboard Volunteer Observing Ships (VOS). Journal of Atmospheric and Oceanic Technology, 25 (1), 93-113. (doi:10.1175/2007JTECHO505.1).

Record type: Article

Abstract

The infrared SST autonomous radiometer (ISAR) is a self-calibrating instrument capable of measuring in situ sea surface skin temperature (SSTskin) to an accuracy of 0.1 K. Extensive field deployments alongside two independent research radiometers measuring SSTskin using different spectral and geometric configurations show that, relatively, ISAR SSTskin has a zero bias ±0.14 K rms. The ISAR instrument has been developed for satellite SST validation and other scientific programs. The ISAR can be deployed continuously on voluntary observing ships (VOS) without any service requirement or operator intervention for periods of up to 3 months. Five ISAR instruments have been built and are in sustained use in the United States, China, and Europe. This paper describes the ISAR instrument including the special design features that enabled a single channel radiometer with a spectral bandpass of 9.6–11.5 ?m to be adapted for autonomous use. The entire instrument infrared optical path is calibrated by viewing two blackbody reference cavities at different temperatures to maintain high accuracy while tolerating moderate contamination of optical components by salt deposition. During bad weather, an innovative storm shutter, triggered by a sensitive optical rain gauge, automatically seals the instrument from the external environment. Data are presented that verify the instrument calibration and functionality in such situations. A watchdog timer and auto-reboot function support automatic data logging recovery in case of power outages typically encountered on ships. An RS485 external port allows supporting instruments that are not part of the core ISAR package (e.g., a solarimeter) to be logged using the ISAR system. All data are processed by the ISAR instrument and are relayed to a host computer via the RS232 serial link as (National Electronics Manufacturers Association) NEMA-style strings allowing easy integration into many commercial onboard scientific data logging systems. In case of a communications failure, data are stored on board using a CompactFlash card that can be retrieved when the instrument is serviced. The success of the design is demonstrated using results obtained over 21 months in the English Channel and Bay of Biscay as part of a campaign to validate SSTskin observations derived from the Environmental Satellite (Envisat) Advanced Along-Track Scanning Radiometer (AATSR).

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Published date: January 2008

Identifiers

Local EPrints ID: 50256
URI: http://eprints.soton.ac.uk/id/eprint/50256
ISSN: 0739-0572
PURE UUID: 4bff8472-880a-4fe1-8779-d884524f034e
ORCID for W. Wimmer: ORCID iD orcid.org/0000-0003-4693-1161

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Date deposited: 04 Feb 2008
Last modified: 16 Mar 2024 03:39

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Contributors

Author: C. Donlon
Author: I.S. Robinson
Author: M. Reynolds
Author: W. Wimmer ORCID iD
Author: G. Fisher
Author: R. Edwards
Author: T.J. Nightingale

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