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Titre : Time-series observations of O2 and CO2 in the Labrador Sea and the parameterization of air-sea gas exchange
Nom du conférencier : Douglas Wallace
Son affiliation : Dalhousie University (Halifax, Canada)
Laboratoire organisateur : LOCEAN
Date et heure : 05-06-2019 11h00
Lieu : Campus Jussieu - Grande salle du LATMOS (couloir 45-46, 4ème étage)
Résumé :

High-frequency time-series of dissolved oxygen and pCO2, as well as other biogeochemical properties, were collected from the upper 150m of the Labrador Sea from a unique, moored profiler over an annual cycle. The data were used to estimate the annual uptake of O2, CO2 and Atmospheric Potential Oxygen in this high-latitude convection region. The results reveal that the parameterization of air-sea gas exchange leads to order-of-magnitude uncertainty in O2 and APO fluxes. Further, uptake of all three quantities is poorly constrained in this region as a result of uncertainties in available wind-speed products.

The study suggests: 1) parameterization of the bubble contribution to the air-sea flux of O2 is highly uncertain and inadequately represented in current biogeochemical models; 2) the turnover time of oxygen in the deep ocean may be under-estimated by current models as a result; 3) the wind-speed regime in high-latitude, high-wind speed regions such as the Labrador Sea needs improved validation. Implications for our understanding of global patterns of ocean deoxygenation and atmospheric APO will be speculated on.

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