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The annual cycle of carbon dioxide and parameters influencing the air-sea carbon exchange in the Baltic Proper
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. (Meteorologi)
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
Baltic Sea Research Institute, Warnemunde, Germany.
Finnish Institute of Marine Research, Helsingfors, Finland.
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2008 (English)In: Journal of Marine Systems, ISSN 0924-7963, Vol. 74, no 1-2, 381-394 p.Article in journal (Refereed) Published
Abstract [en]

A land-based field station, two moored buoys and data from the Finnpartner ship were used to investigate the variability of the air-sea CO2-flux and parameters controlling the flux during one year in the Baltic Sea region.The agreement between the sea surface partial pressure of CO2 measured near the tower and from the ship in the central parts of the Baltic Proper was relatively good during most of the period.But, during periods with intense biological activity or strong upwelling there were significant differences.The flux of CO2 was measured with the eddy-correlation method.The transfer velocity was calculated from the flux measurements and the instrumental uncertainty in calculations of the hourly values of transfer velocity was of the order of 20%.The calculated value of the transfer velocity increased with increasing the wind speed.The relation showed, however, great scatter and no clear wind-dependent relation could be determined.It was shown that for the measured flux and for transfer velocities estimated from measurements it is important to know the variability of pCO2w in the footprint area.This is of particular importance when investigating the processes influencing the flux.When calculating the air-sea flux of CO2 the greatest uncertainty is in the determination of the transfer velocity, but it was shown that also the partial pressure of CO2 in the surface water is crucial to determine with good accuracy.

Place, publisher, year, edition, pages
2008. Vol. 74, no 1-2, 381-394 p.
Keyword [en]
Carbon dioxide, air-sea interaction, air–sea exchange, transfer velocity parameterization, CO2 exchange, eddy-correlation measurements
National Category
Natural Sciences
Research subject
URN: urn:nbn:se:uu:diva-85618DOI: 10.1016/j.jmarsys.2008.02.005ISI: 000261256100023OAI: oai:DiVA.org:uu-85618DiVA: diva2:113685
Available from: 2008-10-23 Created: 2008-10-23 Last updated: 2013-04-30Bibliographically approved
In thesis
1. Air-Sea Fluxes of CO2: Analysis Methods and Impact on Carbon Budget
Open this publication in new window or tab >>Air-Sea Fluxes of CO2: Analysis Methods and Impact on Carbon Budget
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Carbon dioxide (CO2) is an important greenhouse gas, and the atmospheric concentration of CO2 has increased by more than 100 ppm since prior to the industrial revolution.  The global oceans are considered an important sink of atmospheric CO2, since approximately one third of the anthropogenic emissions are absorbed by the oceans. To be able to model the global carbon cycle and the future climate, it is important to have knowledge of the processes controlling the air-sea exchange of CO2. In this thesis, measurements as well as a model is used in order to increase the knowledge of the exchange processes.

The air-sea flux of CO2 is estimated from high frequency measurements using three methods; one empirical method, and two methods with a solid theoretical foundation. The methods are modified to be applicable for various atmospheric stratifications, and the agreement between methods is good in average.

A new parameterization of the transfer velocity (the rate of transfer across the air-sea interface), is implemented in a Baltic Sea model. The new parameterization includes also the mechanism of water-side convection. The impact of including the new parameterization is relatively small due to feedback processes in the model. The new parameterization is however more representative for flux calculations using in-situ measurement or remote sensing products. When removing the feedback to the model, the monthly average flux increases by up to 20% in some months, compared to when water-side convection is not included.

The Baltic Sea carbon budget was estimated using the Baltic Sea model, and the Baltic Sea was found to be a net sink of CO2. This is consistent with some previous studies, while contradictory to others. The dissimilarity between studies indicates the difficulty in estimating the carbon budget mainly due to variations of the CO2 uptake/release in time and space. Local variations not captured by the model, such as coastal upwelling, give uncertainties to the model. Coastal upwelling can alter the uptake/release of CO2 in a region by up to 250%. If upwelling would be included in the model, the Baltic Sea might be considered a smaller sink of CO2.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 47 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1020
air-sea exchange, carbon dioxide, Baltic Sea, eddy-covariance method, inertial dissipation method, cospectral-peak method, Baltic Sea measurements, CO2 fluxes, Galathea 3 expedition, Baltic Sea modeling, water-side convection, coastal upwelling, carbon budget
National Category
Meteorology and Atmospheric Sciences
Research subject
urn:nbn:se:uu:diva-194960 (URN)978-91-554-8599-3 (ISBN)
Public defence
2013-04-05, Hambergsalen, Villavägen 16, Uppsala, 10:00 (English)
Available from: 2013-03-14 Created: 2013-02-20 Last updated: 2013-04-02Bibliographically approved

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