- 1Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Telegrafenberg, 14438 Potsdam, Germany
- 2TU Braunschweig, Institute of Flight Guidance, Hermann-Blenk-Str. 27, 38108 Braunschweig, Germany
- 3GFZ, Telegrafenberg, 14438 Potsdam, Germany
- 4Leipzig Institute for Meteorology, Leipzig University, Leipzig, Germany
- 5Hokkaido University, Hakodate, Hokkaido, Japan
The Arctic region plays a crucial role in the global methane (CH4) budget, as it is anticipated to contain substantial CH4 sources, such as (subsea) permafrost. The sparse network of land-based meteorological observation stations in the Arctic results in significant data gaps, particularly for marine sea-ice covered regions. Ship-based measurements can complement the land-based data enhancing our process understanding of the CH4 cycling in the Arctic including source-sink dynamics.
This study presents ship-borne observations of CH4 concentration and 𝜹13C-CH4 values continuously recorded in air near the ocean/ sea-ice surface with a Picarro G2132-i Isotope Analyzer during Leg 4 (June/July 2020) and Leg 5 (August/September 2020) of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in the Central Arctic. Three approaches to filter contamination by local pollution sources on both time series were compared. Finally, the Pollution Detection Algorithm was applied to the raw data. A comparison with recordings from the closest land stations and their seasonal patterns suggests that the ship-borne data is more closely linked to dynamic changes in methane sources, sinks, and transport processes, rather than being solely driven by seasonality. To unravel underlying processes, which may contribute to variations in the ship-borne data, we employed a two-step approach. First, we defined air mass source areas and transport pathways within the Arctic Ocean boundary layer using five-day backward trajectories modelled with the LAGRANTO analysis tool and ERA5 wind field data. Second, we linked the observed variations to the air mass source regions by utilizing Keeling plot analysis and 𝜹13C-CH4 fingerprints.
Our analysis reveals that variations in the time series are related both to specific geographical source areas and to seasonally different distinct CH4 source strengths within certain source areas. The findings highlight the importance of considering air mass source areas and seasons to understand variations in CH4 concentration and 𝜹13C-CH4 values in the Arctic. The study highlights the need for further collection of ship-borne measurements of CH4 concentration and 𝜹13C-CH4 data to enhance process understanding and modelling approaches.
How to cite: Sellmaier, S., Damm, E., Sachs, T., Kirbus, B., Wiekenkamp, I., Rinke, A., Pätzold, F., Nomura, D., Lampert, A., and Rex, M.: Ship-borne atmospheric measurements during MOSAiC contribute to detect CH4 sources and transport pathways in the Arctic , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19640, https://doi.org/10.5194/egusphere-egu25-19640, 2025.
