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UP: Fachverband Umweltphysik
UP 7: Aquatic Systems: Limnology, Natural Waters, Wetlands and Soilmoisture
UP 7.4: Talk
Wednesday, March 11, 2026, 12:00–12:15, MER/0002
Airborne Lidar Measurements of Methane over Canada — •Arunima Das1,2,3, Christoph Kiemle2,3, Sabrina Zechlau1,2, Martin Wirth2, and Andreas Fix2 — 1Ludwig Maximilian University of Munich — 2Deutsches Zentrum für Luft- und Raumfahrt — 3Technical University of Munich
Methane(CH4) is a key greenhouse gas with an atmospheric lifetime of about 10 years and high mitigation potential. Wetlands, coastal zones and offshore oil and gas facilities are major CH4 sources yet quantifying emissions over these remains challenging. Passive sensors struggle over low-albedo water surfaces and in-situ data are sparse. The French-German MERLIN mission aims to address this gap. Its Integrated Path Differential Absorption(IPDA) lidar will retrieve global column-averaged CH4 independent of sunlight. IPDA maintains high precision over dark water, flooded wetlands, and high-latitude regions with low sun angles. A robust retrieval algorithm performing accurately across diverse surfaces is crucial for detecting small CH4 gradients. CHARM-F, MERLIN's airborne demonstrator provides essential testing. During the CoMet 2.0 campaign, it measured XCH4 across Arctic wetlands and lake systems in the Hudson Bay Lowlands with agreement to in-situ vertical profiles within 1%. Further analysis shows negligible bias over land and higher biases over water, majorly driven by varying signal-to-noise ratio. The upcoming campaign CoMet 3.0 will broaden environmental coverage over tropical wetlands in Brazil, further testing CH4 retrieval performance over extensive water-dominated regions. These observations significantly reduce gaps in global CH4 monitoring.
Keywords: Green House Gas Emission; Lidar Remote Sensing; Methane emission quantification; Wetlands and Water bodies; MERLIN satellite mission