Shipborne eddy covariance observations of methane fluxes constrain Arctic sea emissions.
basic_science · Level V
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- Record sourced from PubMed, PMID 32064354.
- Also identified by DOI 10.1126/sciadv.aay7934 and PMC identifier 6989137.
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Abstract
We demonstrate direct eddy covariance (EC) observations of methane (CH<sub>4</sub>) fluxes between the sea and atmosphere from an icebreaker in the eastern Arctic Ocean. EC-derived CH<sub>4</sub> emissions averaged 4.58, 1.74, and 0.14 mg m<sup>-2</sup> day<sup>-1</sup> in the Laptev, East Siberian, and Chukchi seas, respectively, corresponding to annual sea-wide fluxes of 0.83, 0.62, and 0.03 Tg year<sup>-1</sup>. These EC results answer concerns that previous diffusive emission estimates, which excluded bubbling, may underestimate total emissions. We assert that bubbling dominates sea-air CH<sub>4</sub> fluxes in only small constrained areas: A ~100-m<sup>2</sup> area of the East Siberian Sea showed sea-air CH<sub>4</sub> fluxes exceeding 600 mg m<sup>-2</sup> day<sup>-1</sup>; in a similarly sized area of the Laptev Sea, peak CH<sub>4</sub> fluxes were ~170 mg m<sup>-2</sup> day<sup>-1</sup>. Calculating additional emissions below the noise level of our EC system suggests total ESAS CH<sub>4</sub> emissions of 3.02 Tg year<sup>-1</sup>, closely matching an earlier diffusive emission estimate of 2.9 Tg year<sup>-1</sup>.