The influence of sea-ice cover on air-sea gas exchange estimated with radon-222 profiles


Contact
Michiel.Rutgers.v.d.Loeff [ at ] awi.de

Abstract

Air-sea gas exchange plays a key role in the cycling of greenhouse and other biogeochemically important gases. Although air-sea gas transfer is expected to change as a consequence of the rapid decline in summer Arctic sea ice cover, little is known about the effect of sea-ice cover on gas exchange fluxes, especially in the marginal ice zone. During the Polarstern expedition ARK-XXVI/3 (TransArc, Aug/Sep 2011) to the central Arctic Ocean, we compared 222Rn/226Ra ratios in the upper 50m of 14 ice-covered and 4 ice-free stations. At three of the ice-free stations, we find 222Rn-based gas transfer coefficients in good agreement with expectation based on published relationships between gas transfer and wind speed over open water when accounting for wind history from wind reanalysis data. We hypothesize that the low gas transfer rate at the fourth station results from reduced fetch due to the proximity of the ice edge, or lateral exchange across the front at the ice edge by restratification. No significant radon deficit could be observed at the ice-covered stations. At these stations, the average gas transfer velocity was less than 0.1 m/d (97.5% confidence), compared to 0.5-2.2 m/d expected for open water. Our results show that air-sea gas exchange in an ice-covered ocean is reduced by at least an order of magnitude compared to open water. In contrast to previous studies, we show that in partially ice-covered regions, gas exchange is lower than expected based on a linear scaling to percent ice cover.



Item Type
Article
Authors
Divisions
Primary Division
Programs
Primary Topic
Peer revision
ISI/Scopus peer-reviewed
Publication Status
Published
Eprint ID
35427
DOI 10.1002/2013JC009321

Cite as
Rutgers van der Loeff, M. M. , Cassar, N. , Nicolaus, M. , Rabe, B. and Stimac, I. (2014): The influence of sea-ice cover on air-sea gas exchange estimated with radon-222 profiles , Journal of Geophysical Research-Oceans . doi: 10.1002/2013JC009321


Download
[img]
Preview
PDF
RvdLetalJGR2014.pdf

Download (6MB) | Preview
Cite this document as:

Share


Citation

Research Platforms

Campaigns


Actions
Edit Item Edit Item