Determination of air‐sea ice transfer coefficient for CO2: Significant contribution of gas bubble transport during sea ice growth

Air‐ice CO2 fluxes were measured continuously from the freezing of a young sea‐ice cover until its decay. Cooling seawater was as a sink for atmospheric CO2 but asthe ice crystalsformed,sea ice shifted to a source releasing CO2 to the atmosphere throughout the whole ice growth. Atmospheric warming i...

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Bibliographic Details
Main Authors: Kotovitch, Marie, Moreau, S., Zhou, Jiayun, Vancoppenolle, M., Dieckmann, G., Evers, K.-U., Van Der Linden, Fanny, Thomas, D., Tison, J.-L., Delille, Bruno
Format: Conference Object
Language:English
Published: 2015
Subjects:
Physical
chemical
mathematical & earth Sciences
Earth sciences & physical geography
Physique
chimie
mathématiques & sciences de la terre
Sciences de la terre & géographie physique
Sea ice
Online Access:https://orbi.uliege.be/handle/2268/187935
https://orbi.uliege.be/bitstream/2268/187935/1/Koto_et_al_CO2_Fluxes_Solas15%20BD.pdf
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Summary:Air‐ice CO2 fluxes were measured continuously from the freezing of a young sea‐ice cover until its decay. Cooling seawater was as a sink for atmospheric CO2 but asthe ice crystalsformed,sea ice shifted to a source releasing CO2 to the atmosphere throughout the whole ice growth. Atmospheric warming initiated the decay, re‐shifting sea‐ice to a CO2 sink. Combining these CO2 fluxes with the partial pressure of CO2 within sea ice, we determined gas transfer coefficients for CO2 at air‐ice interface for growth and decay. We hypothesize that this difference originates from the transport of gas bubbles during ice growth, while only diffusion occurs during ice melt. In parallel, we used a 1D biogeochemical model to mimic the observed CO2 fluxes. The formation of gas bubbles was crucial to reproduce fluxes during ice growth where gas bubbles may account for up to 92 % of the upward CO2 fluxes.

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