Abstract :
[en] 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 (CH4) 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 CH4 flux ranging from +0.2 to +2.1 mg CH4 m−2 d−1 in open leads. CH4 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, CH4 concentrations in the sea ice brine were above the equilibrium with the atmosphere. As the ice grew thicker, most of the CH4 was lost from upper layers of sea ice into the atmosphere, implying continued CH4 evasion after the leads were ice–covered. This suggests that wintertime CH4 emissions need to be better constrained.
Funding text :
We thank the captain, engineers, and crew of R/V Lance for technical and logistic support during the entire N–ICE2015 expedition. We thanks Paul Dodd for help with the sampling of thin ice and under–ice water; Jari Haapala for providing a time–lapse of radar images from the dataset; Ellen Damm for measurements of dissolved CH 4 concentrations in under–ice water samples, and insightful discussions at early stage of this manuscript preparation; and Gunnar Spreen for providing sea–ice fraction area data. The N–ICE2015 expedition was supported by the N–ICE project at the former Centre for Ice , Climate and Ecosystems at the Norwegian Polar Institute . This study is a part of the CAGE (Centre for Arctic Gas Hydrate, Environment, and Climate), Norwegian Research Council grant no. 223259 . Part of the field work and sampling was funded by the Flagship research program “Ocean Acidification and effects in northern waters” within the FRAM– High North Research Centre for Climate and the Environment (AF) . This work was supported by the Japan Society for the Promotion of Science ( 15K16135 , 17H04715 , 18H03745 , 20H04345 ). MK and BD are PhD students and research associate, respectively, of the F.R.S.–FNRS. The N–ICE2015 expedition was supported by the N–ICE project at the former Centre for Ice , Climate and Ecosystems at the Norwegian Polar Institute . This study is a part of the CAGE (Centre for Arctic Gas Hydrate, Environment, and Climate), Norwegian Research Council grant no. 223259 . Part of the field work and sampling was funded by the Flagship research program “Ocean Acidification and effects in northern waters” within the FRAM–High North Research Centre for Climate and the Environment (AF) . MK and BD are PhD students and research associate, respectively, of the F.R.S.–FNRS. The data supporting the conclusions of this study are freely available at the Norwegian Polar Data Centre (data.npolar.no) and should be cited as Silyakova, A., Kotovich, M., Fransson, A., Nomura, D., Delille, B., Damm, E., Chierici, M., and Granskog, M. A. (2022). N–ICE2015 methane concentrations in new sea ice and under–ice water [Data set]. Norwegian Polar Institute. https://doi.org/10.21334/npolar.2022.9ef02026 .We thank the captain, engineers, and crew of R/V Lance for technical and logistic support during the entire N–ICE2015 expedition. We thanks Paul Dodd for help with the sampling of thin ice and under–ice water; Jari Haapala for providing a time–lapse of radar images from the dataset; Ellen Damm for measurements of dissolved CH4 concentrations in under–ice water samples, and insightful discussions at early stage of this manuscript preparation; and Gunnar Spreen for providing sea–ice fraction area data. The N–ICE2015 expedition was supported by the N–ICE project at the former Centre for Ice, Climate and Ecosystems at the Norwegian Polar Institute. This study is a part of the CAGE (Centre for Arctic Gas Hydrate, Environment, and Climate), Norwegian Research Council grant no. 223259. Part of the field work and sampling was funded by the Flagship research program “Ocean Acidification and effects in northern waters” within the FRAM– High North Research Centre for Climate and the Environment (AF). This work was supported by the Japan Society for the Promotion of Science (15K16135,17H04715, 18H03745, 20H04345). MK and BD are PhD students and research associate, respectively, of the F.R.S.–FNRS. The N–ICE2015 expedition was supported by the N–ICE project at the former Centre for Ice, Climate and Ecosystems at the Norwegian Polar Institute. This study is a part of the CAGE (Centre for Arctic Gas Hydrate, Environment, and Climate), Norwegian Research Council grant no. 223259. Part of the field work and sampling was funded by the Flagship research program “Ocean Acidification and effects in northern waters” within the FRAM–High North Research Centre for Climate and the Environment (AF). MK and BD are PhD students and research associate, respectively, of the F.R.S.–FNRS. The data supporting the conclusions of this study are freely available at the Norwegian Polar Data Centre (data.npolar.no) and should be cited as Silyakova, A. Kotovich, M. Fransson, A. Nomura, D. Delille, B. Damm, E. Chierici, M. and Granskog, M. A. (2022). N–ICE2015 methane concentrations in new sea ice and under–ice water [Data set]. Norwegian Polar Institute. https://doi.org/10.21334/npolar.2022.9ef02026.
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