ALICE - Airborne tool for methane isotopic composition and polar meteorological experiments
Final Report Abstract
In the project ALICE, two quadrocopters were developed with the capabilities to measure temperature and humidity and to take 12 air samples with standard glass bottles for laboratory analyses of the methane stable carbon isotopic composition. The original aim was to deploy them at a coastal Antarctic site to identify the methane source that leads to a seasonal increase of the methane concentration. The glass bottles were evacuated before the flight. An electromagnetic valve was triggered either manually or at predefined altitudes to open the valve and take the air sample. Leak tightness was monitored continuously by recording the inside pressure in the glass bottles. A major challenge was that the manual valves of the standard glass bottles were not leak tight in the open position under cold conditions. Several modifications of the glass bottles were tested. The planned measurements in the Antarctic did not take place as additional funding by the partners, the Chilean Funding Agency was not provided. However, measurements were performed during a Polarstern cruise in 2017. This was the first time that quadrocopter measurements were allowed from the helideck, and procedures were established. Temperature and humidity profiles were recorded with high resolution, that show the smallscale and short-term variability of these atmospheric parameters. Further, two short measurement campaigns were performed in spring and autumn at a rewetted peatland site, which is known as a biologically-induced methane source. It was shown that the isotopic composition was different near the surface and up to the altitude of the temperature inversion in the early morning compared to the isotopic composition above the temperature inversion. After sunrise and vertical mixing of the atmospheric boundary layer, the isotopic composition was the same for all the the sampling altitudes up to 1000 m. These results confirm the hypotheses that analysing air samples for different altitudes is a suitable method to detect small-scale methane sources, and that thermal stratification plays a major role in the vertical distribution of methane.
Publications
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The Expedition PS109 of the Research Vessel POLARSTERN to the Nordic Seas in 2017, Berichte zur Polar- und Meeresforschung = Reports on polar and marine research, Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 715, 139 pp. 2018
Kanzow, T. et al.
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Studying boundary layer methane isotopy and vertical mixing processes at a rewetted peatland site using an unmanned aircraft system, Atmos. Meas. Tech., 13, 1937–1952, 2020
Lampert, A., Pätzold, F., Asmussen, M., Lobitz, L., Krüger, T., Rausch, T., Sachs, T., Wille, C., Sotomayor Zakharov, D., Gaus, D., Bansmer, S., and Damm, E.
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Unmanned Aerial Systems for Investigating the Polar Atmospheric Boundary Layer – Technical Challenges and Examples of Applications, Atmosphere, 11, 416, 25 pp., 2020
Lampert, A., Altstädter, B., Bärfuss, K., Bretschneider, L., Sandgaard, J., Lobitz, L., Asmussen, M., Damm, E., Käthner, R., Krüger, T., Lüpkes, C., Nowak, S., Peuker, A., Rausch, T., Reiser, F., Scholtz, A., Sotomayor Zakharov, D., Gaus, D., Bansmer, S., Wehner, B., and Pätzold, F.
