Advancing the Arctic Methane Permafrost Challenge (AMPAC) With Future Satellite Missions

Permafrost degradation in the Arctic is accelerating and is forecast to enhance greenhouse gas (GHG) emissions from the large permafrost carbon pool. Earth Observation has a key role in determining GHG sources and sinks, and multiple current and future missions are useful to track baseline parameters for determining GHG fluxes. NASA and ESA have initialized the Arctic Methane and Permafrost Challenge (AMPAC) as a transatlantic networking action that strives to promote related scientific work and improve observation capabilities. Key variables observable from space include methane concentrations as well as landcover properties to inform process-based models as proxy for sources as well as temperature-related constraints for microbial activity. Upcoming missions are expected to advance these capabilities significantly with increased sampling intervals through future synthetic aperture radar missions and constellations of multiple multispectral sensors. This will allow better representation of seasonality and advance methane source attribution in general. In addition, continuity of current missions which provide greenhouse gas observations, including methane, is crucial. Hyper- and superspectral sensors targeting primarily landsurface observation are expected to complement methane retrievals through identification of emission hotspots. Arctic monitoring also requires active optical instruments for concentration retrieval, a type of instrumentation which is still novel for satellite-based observations. A comprehensive portfolio of hyperspectral, passive microwave, synthetic aperture radar, altimeter and landsurface temperature and lidar measurements in addition to imaging spectrometers will be available by 2032/33, at the time of the International Polar Year. This will allow for advanced experiments when also accompanying in situ observations become available.