Descriptive Statistical Analysis of Non-Wetland Methane (CH₄) Fluxes to Inform Modeling of the Global CH4 Soil Sink

M. Yonker, O. Briner and G. McNicol

Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, Illinois 60607; 847-850-9913, E-mail: myonke2@uic.edu

Natural wetlands constitute roughly one-third of the annual global methane (CH₄) sources while uplands constitute the largest biological CH₄ sink. Previous analyses of the FLUXNET-CH4 Community Product, the largest yet compilation of surface CH₄ fluxes, have improved our empirical understanding and models of wetland CH₄ emissions, but non-wetland sites have not been investigated as thoroughly. To better quantify regional and global CH₄ emissions, including net uptake across uplands, we explore the statistical properties of non-wetland CH₄ fluxes in the FLUXNET-CH4 Community Product, including analysis of trends across biomes, seasons, and ecosystem types. These analyses will assist in the development of a knowledge-guided machine learning model with collaborators at NOAA and DOE.

Figure 1. Methane fluxes across non-wetland sites organized by land cover type included in the FLUXNET-CH4 Community Product v1. Fluxes for all upland cover types are distinct from wetland cover due to a larger share of data near 0 nmol m-2 s-1 and slightly more negative for forests.