the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Significant methane undersaturation during austral summer in the Ross Sea (Southern Ocean)
Abstract. Dissolved methane (CH4) was measured at 9 stations along a transect at 75° S in the Ross Sea during austral summer in January 2020. CH4 undersaturation (mean: 82 ± 20 %) was found in the water column, with a mean air-sea CH4 flux density of −0.58 ± 0.48 μmol m−2 day−1, which suggests that the Ross Sea was a net sink for atmospheric CH4 during the austral summer. Simple box-model calculations revealed that the CH4 depletion should occur in the surface mixed layer because of CH4 oxidation and advection of CH4-poor waters. We propose that freshwater injection caused by sea-ice melting in summer dilutes CH4 concentrations within the surface layer and thus increases its potential for atmospheric CH4 uptake in the Ross Sea. Thus, we argue that both CH4 consumption and sea-ice melting are important drivers of CH4 undersaturation, which implies that the high-latitude area of the Southern Ocean is a sink for atmospheric CH4. We estimated that the Southern Ocean (> 65° S) takes up about 0.02 % of the global CH4 emissions and thus represents a minor sink for atmospheric CH4.
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Status: closed
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RC1: 'Comment on bg-2021-334', Anonymous Referee #1, 27 Jan 2022
- AC1: 'Reply on RC1', Wangwang Ye, 24 Mar 2022
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RC2: 'Comment on bg-2021-334', Anonymous Referee #2, 22 Feb 2022
- AC2: 'Reply on RC2', Wangwang Ye, 24 Mar 2022
Status: closed
-
RC1: 'Comment on bg-2021-334', Anonymous Referee #1, 27 Jan 2022
- AC1: 'Reply on RC1', Wangwang Ye, 24 Mar 2022
-
RC2: 'Comment on bg-2021-334', Anonymous Referee #2, 22 Feb 2022
- AC2: 'Reply on RC2', Wangwang Ye, 24 Mar 2022
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