Constraints on oceanic methane emissions west of svalbard from atmospheric in situ measurements and lagrangian transport modeling

Autor(en): I. Pisso, C. Lund Myhre, S. M. Platt, S. Eckhardt, O. Hermansen, N. Schmidbauer, J. Mienert, S. Vadakkepuliyambatta, S. Bauguitte, J. Pitt, G. Allen, K. N. Bower, S. O’Shea, M. W. Gallagher, C. J. Percival, J. Pyle, M. Cain, A. Stohl
Abstrakt: Methane stored in seabed reservoirs such as methane hydrates can reach the atmosphere in the form of bubbles or dissolved in water. Hydrates could destabilize with rising temperature further increasing greenhouse gas emissions in a warming climate. To assess the impact of oceanic emissions from the area west of Svalbard, where methane hydrates are abundant, we used measurements collected with a research aircraft (Facility for Airborne Atmospheric Measurements) and a ship (Helmer Hansen) during the Summer 2014 and for Zeppelin Observatory for the full year. We present a model-supported analysis of the atmospheric CH₄ mixing ratios measured by the different platforms. To address uncertainty about where CH⁴ emissions actually occur, we explored three scenarios: areas with known seeps, a hydrate stability model, and an ocean depth criterion. We then used a budget analysis and a Lagrangian particle dispersion model to compare measurements taken upwind and downwind of the potential CH₄ emission areas. We found small differences between the CH₄ mixing ratios measured upwind and downwind of the potential emission areas during the campaign. By taking into account measurement and sampling uncertainties and by determining the sensitivity of the measured mixing ratios to potential oceanic emissions, we provide upper limits for the CH₄ fluxes. The CH₄ flux during the campaign was small, with an upper limit of 2.5 nmolm^-2 s^-1 in the stability model scenario. The Zeppelin Observatory data for 2014 suggest CH⁴ fluxes from the Svalbard continental platform below 0.2 Tg yr^-1. All estimates are in the lower range of values previously reported.
Organisation(en): Institut für Meteorologie und Geophysik
Externe Organisation(en): Norwegian Institute for Air Research, University of Tromsø - The Arctic University of Norway, Natural Environment Research Council, University of Manchester, National Centre for Atmospheric Sciences (NCAS), University of Cambridge
Journal: Journal of Geophysical Research
Band: 121
Seiten: 14,188-14,200
ISSN: 0148-0227
DOI: https://doi.org/10.1002/2016JD025590
Publikationsdatum: 12-2016
Peer-reviewed: Ja
ÖFOS 2012: 105206 Meteorologie
ASJC Scopus Sachgebiete: Condensed Matter Physics, Physical and Theoretical Chemistry, Polymers and Plastics, Materials Chemistry
Sustainable Development Goals: SDG 13 – Maßnahmen zum Klimaschutz
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/e2cfbc89-61bf-40f6-88a1-474e51ff3c82

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