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

• 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: Arctic; Polar Science; Sea ice
• Online Access: https://hdl.handle.net/10037/27745; https://doi.org/10.1016/j.polar.2022.100874

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.