Methane release from open leads and new ice following an Arctic winter storm event

We examine an Arctic winter storm event, which led to ice break–up, the formation of open leads, and the subsequent freezing of these leads. The methane (CH 4 ) concentration in under–ice surface water before and during the storm event was 8–12 nmol L −1 , which resulted in a potential sea–to–air CH...

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Bibliographic Details
Published in:Polar Science
Main Authors: Silyakova, Anna, Nomura, Daiki, Kotovitch, Marie, Fransson, Agneta, Delille, Bruno, Chierici, Melissa, Granskog, Mats A.
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2022
Subjects:
Online Access:https://hdl.handle.net/10037/27745
https://doi.org/10.1016/j.polar.2022.100874
Description
Summary:We examine an Arctic winter storm event, which led to ice break–up, the formation of open leads, and the subsequent freezing of these leads. The methane (CH 4 ) concentration in under–ice surface water before and during the storm event was 8–12 nmol L −1 , which resulted in a potential sea–to–air CH 4 flux ranging from +0.2 to +2.1 mg CH 4 m −2 d −1 in open leads. CH 4 ventilation between seawater and atmosphere occurred when both open water fraction and wind speed increased. Over the nine days after the storm, sea ice grew 27 cm thick. Initially, CH 4 concentrations in the sea ice brine were above the equilibrium with the atmosphere. As the ice grew thicker, most of the CH 4 was lost from upper layers of sea ice into the atmosphere, implying continued CH 4 evasion after the leads were ice–covered. This suggests that wintertime CH 4 emissions need to be better constrained.