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Intercomparison of shipboard and moored CARIOCA buoy seawater fCO2 measurements in the Sargasso Sea

Intercomparison of shipboard and moored CARIOCA buoy seawater fCO2 measurements in the Sargasso Sea
Intercomparison of shipboard and moored CARIOCA buoy seawater fCO2 measurements in the Sargasso Sea
The ocean is an important sink for carbon and heat, yet high-resolution measurements of biogeochemical properties relevant to global climate change are being made only sporadically in the ocean at present. There is a growing need for automated, real-time, long-term measurements of CO2 in the ocean using a network of sensors, strategically placed on ships, moorings, free-drifting buoys and autonomous remotely operated vehicles. The ground-truthing of new sensor technologies is a vital component of present and future efforts to monitor changes in the ocean carbon cycle and air–sea exchange of CO2.

A comparison of a moored Carbon Interface Ocean Atmosphere (CARIOCA) buoy and shipboard fugacity of CO2 (fCO2) measurements was conducted in the western North Atlantic during two extended periods (>1 month) in 1997. The CARIOCA buoy was deployed on the Bermuda Testbed Mooring (BTM), which is located 5 km north of the site of the US Joint Global Ocean Flux Study (JGOFS) Bermuda Atlantic Time-series Study (BATS). The high frequency of sampling revealed that temperature and fCO2 responded to physical forcing by the atmosphere on timescales from diurnal to 4–8 days. Concurrent with the deployments of the CARIOCA buoy, frequent measurements of surface fCO2 were made from the R/V Weatherbird II during opportunistic visits to the BTM and BATS sites, providing a direct calibration of the CARIOCA buoy fCO2 data. Although, the in situ ground-truthing of the CARIOCA buoy was complicated by diurnal processes, sub-mesoscale and fine-scale variability, the CARIOCA buoy fCO2 data was accurate within 3±6 µatm of shipboard fCO2 data for periods up to 50 days. Longer-term assessments were not possible due to the CARIOCA buoy breaking free of the BTM and drifting into waters with different fCO2-temperature properties. Strategies are put forward for future calibration of other in situ sensors.
0304-4203
239-255
Bates, Nicholas R.
954a83d6-8424-49e9-8acd-e606221c9c57
Merlivat, Liliane
59f0a989-d3bf-4be0-91a6-237a8dde0c24
Beaumont, Laurence
994e8dc0-eedf-4401-8bb1-cc72c6d1909a
Pequignet, A.Christine
2286a932-3dea-44ba-8a5d-ca985363fb3b
Bates, Nicholas R.
954a83d6-8424-49e9-8acd-e606221c9c57
Merlivat, Liliane
59f0a989-d3bf-4be0-91a6-237a8dde0c24
Beaumont, Laurence
994e8dc0-eedf-4401-8bb1-cc72c6d1909a
Pequignet, A.Christine
2286a932-3dea-44ba-8a5d-ca985363fb3b

Bates, Nicholas R., Merlivat, Liliane, Beaumont, Laurence and Pequignet, A.Christine (2000) Intercomparison of shipboard and moored CARIOCA buoy seawater fCO2 measurements in the Sargasso Sea. Marine Chemistry, 72 (2-4), 239-255. (doi:10.1016/S0304-4203(00)00084-0).

Record type: Article

Abstract

The ocean is an important sink for carbon and heat, yet high-resolution measurements of biogeochemical properties relevant to global climate change are being made only sporadically in the ocean at present. There is a growing need for automated, real-time, long-term measurements of CO2 in the ocean using a network of sensors, strategically placed on ships, moorings, free-drifting buoys and autonomous remotely operated vehicles. The ground-truthing of new sensor technologies is a vital component of present and future efforts to monitor changes in the ocean carbon cycle and air–sea exchange of CO2.

A comparison of a moored Carbon Interface Ocean Atmosphere (CARIOCA) buoy and shipboard fugacity of CO2 (fCO2) measurements was conducted in the western North Atlantic during two extended periods (>1 month) in 1997. The CARIOCA buoy was deployed on the Bermuda Testbed Mooring (BTM), which is located 5 km north of the site of the US Joint Global Ocean Flux Study (JGOFS) Bermuda Atlantic Time-series Study (BATS). The high frequency of sampling revealed that temperature and fCO2 responded to physical forcing by the atmosphere on timescales from diurnal to 4–8 days. Concurrent with the deployments of the CARIOCA buoy, frequent measurements of surface fCO2 were made from the R/V Weatherbird II during opportunistic visits to the BTM and BATS sites, providing a direct calibration of the CARIOCA buoy fCO2 data. Although, the in situ ground-truthing of the CARIOCA buoy was complicated by diurnal processes, sub-mesoscale and fine-scale variability, the CARIOCA buoy fCO2 data was accurate within 3±6 µatm of shipboard fCO2 data for periods up to 50 days. Longer-term assessments were not possible due to the CARIOCA buoy breaking free of the BTM and drifting into waters with different fCO2-temperature properties. Strategies are put forward for future calibration of other in situ sensors.

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Published date: 2000
Organisations: Ocean Biochemistry & Ecosystems

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Local EPrints ID: 358341
URI: http://eprints.soton.ac.uk/id/eprint/358341
ISSN: 0304-4203
PURE UUID: b9413109-eaed-4309-a48a-de09b3d7871d

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Date deposited: 03 Oct 2013 14:16
Last modified: 14 Mar 2024 15:03

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Contributors

Author: Liliane Merlivat
Author: Laurence Beaumont
Author: A.Christine Pequignet

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