Article in Geophysical Research Letters (GRL) "Direct determination of the air-sea CO2 gas transfer velocity in Arctic sea-ice regions"


John Prytherch1,3, Ian M. Brooks1, Patrick M. Crill2, Brett F. Thornton2, Dominic J. Salisbury1, Michael Tjernström3, Leif G. Anderson4, Marc  C. Geibel5, and Christoph Humborg6.

1 School of Earth and Environment, University of Leeds, Leeds, UK

2 Department of Geological Sciences, Stockholm University, Sweden

3 Department of Meteorology & Bolin Centre for Climate Research, Stockholm University, Sweden

4 Department of Marine Sciences, University of Gothenburg, Sweden

5 Baltic Sea Centre, Stockholm University, Sweden

6 Department of Environmental Science and Analytical Chemistry, Stockholm University, Sweden


Key Points
Eddy covariance measurements of air-sea gas transfer velocity from an icebreaker in open water and sea-ice regions of the Eastern Arctic

Open water measurements in agreement with bulk parameterizations

Air-sea gas transfer velocity has a near-linear dependence on decreasing sea-ice concentration

Abstract
The Arctic Ocean is an important sink for atmospheric CO2. The impact of decreasing sea-ice extent and expanding marginal ice zones on Arctic air-sea CO2 exchange depends on the rate of gas transfer in the presence of sea ice. Sea ice acts to limit air-sea gas exchange by reducing contact between air and water, but is also hypothesised to enhance gas transfer rates across surrounding open water surfaces through physical processes such as increased surface-ocean turbulence from ice-water shear and ice-edge form drag. Here we present the first direct determination of the CO2 air-sea gas transfer velocity in a wide range of Arctic sea-ice conditions. We show that the gas transfer velocity increases near-linearly with decreasing sea-ice concentration. We also show that previous modeling approaches overestimate gas transfer rates in sea-ice regions.


Bolin Centre for Climate Research
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