Characterizing Scale-Dependent Variance and Flux Patterns Across Heterogeneous Permafrost Landscapes Using Airborne Measurements

Low-level airborne eddy covariance measurements enable the characterization of how surface heterogeneity in Arctic permafrost regions influences the spatial variability of greenhouse gas exchange. This study uses the Polar-5 aircraft to collect high-frequency (20 Hz) data on wind, CO₂, and CH₄ over the Mackenzie Delta, Canada, in 2013. The aircraft operated at approximately 40–60 m above ground level (AGL), enabling detailed observation of near-surface greenhouse gas flux. Flight legs were partitioned into three regions based on surface-type classifications, elevation, and degree of surface heterogeneity. Using wavelet analyses, the scale-dependent variances and covariances (fluxes) are quantified across horizontal scales ranging from microscale (10 m – 2 km) to mesoscale (2-10 km). The results demonstrate that scalar variances exhibit clear scale dependence, linked to surface types, elevation, and the level of heterogeneity. Specifically, CH₄ and CO₂ concentrations and fluxes exhibit enhanced small-scale variability over highly heterogeneous terrain, whereas wetland- and lake-dominated regions are characterized by stronger mesoscale variability. By partitioning the domain into three regions, we highlight how the underlying state of permafrost and surface classification jointly affect greenhouse gas flux. Our findings provide a process-based framework that connects heterogeneity level, variance scaling, and the detectability of airborne fluxes in Arctic permafrost landscapes, thereby enhancing the interpretation of aircraft eddy covariance measurements for regional greenhouse gas budgets, compared to flux tower measurements.