Environmental Drivers of Arctic Methane Emissions Hot Spots Determined from Remote Sensing Datasets

Methane emissions from the Arctic are a critical part of the global carbon cycle, particularly due to the positive feedback associated with melting of the permafrost. Some of the factors influencing Arctic methane emissions include local environmental and climatic factors, such as microtopography, geology, soils, hydrologic conditions, and vegetation. Understanding the occurrence of methane hotspots with respect to the spatial variation and heterogeneity of the environmental factors is important for upscaling methane emissions and for improved estimation of methane emissions across the pan-Arctic. We studied methane hotspots over the Kuparuk River basin, North Slope Alaska, and the Mackenzie Delta in northern Canada using airborne imaging spectroscopy collected as part of the Arctic Boreal Vulnerability Experiment (ABoVE). Methane hotspots, defined here as column integrated enhancements greater more than 3000 ppm-m, were derived from NASA's Next-Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) flown in 2017. We correlated data from various remote sensing products with methane hotspots to identify the environmental drivers of methane emissions in the study regions. Vegetation indices (such as the Normalized Difference Vegetation Index) derived from imaging spectroscopy data and existing vegetation classifications were used as vegetation community indicators. The influence of hydrologic features on methane hotspots was studied using datasets indicating the presence of lake features and the proximity to waterbodies derived from AVIRIS-NG data. Using high resolution Digital Elevation Models (DEM) of the Arctic, we studied the influence of changes in elevation and slope on the spatial distribution of methane hotspots. Preliminary results over the Kuparuk river basin indicate the presence positive correlations between methane hotspot emissions and elevation, and negative correlations with shrub biomass. We also identified spatial clusters among the hotspots in Mackenzie basin, possibly indicating the presence of underlying geological factors and/or the effects of exploratory activities influencing the hotspots. We will further study these correlations and present results on spatial patterns and differences among vegetation communities.