Average estimated methane fluxes shown at 1° x 1° resolution (Above Top), and corresponding estimated uncertainties (Above Bottom). The CarbonTracker-CH4 data assimilation produces estimates of scaling factors for continental-sized regions, and these are applied to the prior flux estimate distributions to produce the post-assimilation map on the top. The resulting methane fluxes are in optimal agreement with the atmospheric observations used in the assimilation. The scaling factors are applied uniformly to the prior flux estimates within each source region in order to produce the map at the top. The uncertainty estimates are distributed evenly over each continental-scale source region so there is no variability within region. Units are mg (CH4) m2 d-1
Average zonal sums of estimated methane fluxes. The shaded area indicates the estimated 1-sigma uncertainty bounds of the average zonal flux estimates. Units are Tg (CH4) yr-1. The global/North American totals are shown at the bottom right.