Sources of the greenhouse gas methane (CH4), which is many times more effective than carbon dioxide (CO2), have not yet been researched sufficiently scientifically. Methane sources in Scandinavia include the oil and gas industry, but there are also strong natural sources. In wetlands, peat bogs and lakes, CH4 is produced by organic degradation processes. However, corresponding emission inventories and models still differ, sometimes significantly.
As part of MAGIC 2021 (Monitoring of Atmospheric composition and Greenhouse gases through multi-Instruments Campaigns), about 80 researchers based in Kiruna/Sweden, collected greenhouse gas data in northern Scandinavia from August 14 to 27. The goals of the campaign are to estimate methane sources, validate remote sensing data at high latitudes, compare different methods, and prepare future satellite missions by testing new measurement instruments.
The three research aircraft in the Arena Arctica hangar in Kiruna: SAFIRE ATR-42, BAS Twin Otter, DLR Cessna. Credit: DLR/A. Fix (CC BY-ND-NC 3.0).
The Institute of Atmospheric Physics participated with high-resolution in-situ measurements with DLR's own Cessna Grand Caravan and with the worldwide unique lidar instrument CHARM-F (CH4 Atmospheric Remote Monitoring) for methane and CO2 detection, which was used for the first time on the French research aircraft ATR-42 at MAGIC. A space-qualified version of the lidar will provide global methane data from space on the MERLIN satellite mission starting in 2027. A Twin Otter from the British Polar Research Institute (BAS) probed the temperature spectrum of the ground using a passive remote sensing instrument (HyTES). The research also incorporates observations from mobile and fixed ground stations, stratospheric balloons and various satellites.
Measurement flights of SAFIRE ATR-42 (reddish, ©SAFIRE) and DLR Cessna (blueish, ©DLR) during MAGIC in northern Scandinavia. Colored background: Numerical simulation (JSBACH-HIMMELI, Credit: T. Markkanen, M. Raivonen) of methane emissions from wetlands.
Measuring long-lived greenhouse gases is challenging because even near strong sources, levels are usually only less than one percent elevated above background concentrations. Remote sensing instruments additionaly rely on good visibility. The region is often overcast, but without rain there would be no wetlands either. Challenges for the DLR Cessna pilots were the few airfields for alternate landings or refueling stops in this very sparsely populated area. Very short notice flight planning was often required to adapt to the rapidly changing weather conditions, sometimes with further adjustments while still in flight. Due to the very good mobile phone coverage even in remote areas, it was even possible to spontaneously coordinate an additional flight between the Cessna crew currently flying and the ground team.
View from DLR Cessna: ATR-42 during a formation flight to compare measurement instruments (left); Wetlands in the border region between Sweden, Finland and Norway (right). Credits: DLR/A. Fiehn, K. Gottschaldt (CC BY-ND-NC 3.0).
At the end of the campaign, all participants could be pleased about many successful measurements. In addition to extensive wetlands in Sweden, Finland and Norway, Lake Abisko north of Kiruna was flown several times. A flight with CHARM-F in combination with the French wind lidar LIVE also targeted the emission plumes of gas platforms off the Norwegian coast. The coordinated measurements will be jointly evaluated as part of the AMPAC initiative.