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| Titel |
Constraints on oceanic methane emissions west of Svalbard from atmospheric in situ measurements and Lagrangian transport modeling |
| VerfasserIn |
Ignacio Pisso, Cathrine Lund Myhre, Stephen Matthew Platt, Sabine Eckhardt, Ove Hermansen, Norbert Schmidbauer, Jürgen Mienert, Sunil Vadakkepuliyambatta, Stephane Bauguitte, Joseph Pitt, Grant Allen, Keith Bower, Sebastian O'shea, Martin Gallagher, Carl Percival, John Pyle, Michelle Cain, Andreas Stohl |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250154428
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| Publikation (Nr.) |
 EGU/EGU2017-19523.pdf |
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| Zusammenfassung |
| 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 (FAAM) 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 nmol / m s in the stability model scenario. The Zeppelin
Observatory data for 2014 suggests CH4 fluxes from the Svalbard continental platform
below 0.2 Tg/yr . All estimates are in the lower range of values previously reported. |
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