Methane flux estimates from continuous atmospheric measurements and surface-water observations in the northern Labrador Sea and Baffin Bay

• DOI: 10.5194/egusphere-2022-545
• Publication Date: 2022-07-12T13:19:19Z
• Authors: Judith Vogt; David Risk; Kumiko Azetsu-Scott; Evan N. Edinger; Owen A. Sherwood
• Keywords: Baseline (sea); Fjord; Atmospheric methane; Petroleum seep

Abstract. Vast amounts of methane (CH4) stored in permafrost and submarine sediments are susceptible to release a warming Arctic, further exacerbating climate change positive feedback. It is therefore critical monitor CH4 over pan-regional scales detect early signs release. However, our ability hampered remote northern regions by sampling logistical constraints few good baseline data exist many areas. To create study current background levels North Atlantic waters, we collected continuous real-time atmospheric data, along with ambient air temperature wind parameters 22 days summer 2021 on roughly 5100 km voyage the Labrador Sea Baffin Bay up 71° N. In addition, measured concentrations water column using discrete samples at selected stations. Measured mixing ratios ranged from 1944.7 ppb 2012.0 ppb, mean 1966.0±7.4 1954.2−1980.6 ppb. Dissolved near-surface peaked 56.58±0.05 nM within 1 down-current known cold seep Scott Inlet but were consistently super-saturated throughout Southwind Fjord, which an area recently affected landslides. Local sea-air fluxes 0.1−14.1 µmol m-2 d-1 indicating that ocean acted as source atmosphere. Atmospheric also driven meteorological, spatial, temporal variations. Highest detected Cumberland Sound Nunavut, suggesting onshore sources nearby waterbodies wetlands, whereas ocean-based contributions this location could not be ruled out. Coupled measurements marine have potential provide ongoing monitoring region releases, well validation for global-scale modelling.