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Title: Dried, closed-path eddy covariance method for measuring carbon dioxide flux over sea ice

Abstract. The Arctic marine environment plays an important role inthe global carbon cycle. However, there remain large uncertainties in howsea ice affects air–sea fluxes of carbon dioxide (CO2), partially dueto disagreement between the two main methods (enclosure and eddy covariance)for measuring CO2 flux (FCO2). The enclosure method has appearedto produce more credible FCO2 than eddy covariance (EC), but is notsuited for collecting long-term, ecosystem-scale flux datasets in suchremote regions. Here we describe the design and performance of an EC systemto measure FCO2 over landfast sea ice that addresses the shortcomingsof previous EC systems. The system was installed on a 10m tower onQikirtaarjuk Island – a small rock outcrop in Dease Strait located roughly35km west of Cambridge Bay, Nunavut, in the Canadian Arctic Archipelago. Thesystem incorporates recent developments in the field of air–sea gasexchange by measuring atmospheric more » CO2 using a closed-path infrared gasanalyzer (IRGA) with a dried sample airstream, thus avoiding the known watervapor issues associated with using open-path IRGAs in low-flux environments.A description of the methods and the results from 4 months of continuousflux measurements from May through August 2017 are presented, highlightingthe winter to summer transition from ice cover to open water. We show thatthe dried, closed-path EC system greatly reduces the magnitude of measuredFCO2 compared to simultaneous open-path EC measurements, and for thefirst time reconciles EC and enclosure flux measurements over sea ice. Thisnovel EC installation is capable of operating year-round on solar and windpower, and therefore promises to deliver new insights into the magnitude ofCO2 fluxes and their driving processes through the annual sea icecycle.

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Authors:
;
Award ID(s):
1840868
Publication Date:
NSF-PAR ID:
10097326
Journal Name:
Atmospheric Measurement Techniques
Volume:
11
Issue:
11
Page Range or eLocation-ID:
6075 to 6090
ISSN:
1867-8548
Sponsoring Org:
National Science Foundation
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