Integrating diverse observations of North American CH4 into flux inversions in CarbonTrackerLagrange-CH4
Wednesday, 16 December 2015
Poster Hall (Moscone South)
A wide array of observations have recently emerged that can provide top-down constraints on North American methane (CH4) emissions estimates: measurements made in-situ and from flasks at the surface, on towers, aboard ships, and aboard aircraft as part of the North American Carbon Program; and retrievals of column averaged mole fractions taken from the surface by the Total Carbon Column Observation Network (TCCON), and from space by the Greenhouse Gases Observing Satellite (GOSAT). We use the CarbonTracker-Lagrange CH4 inverse modeling framework to investigate the utility of the different observation types, and to find optimal methods of integrating them. We examine the impact of weighting data using various models of uncertainty constrained by restricted maximum likelihood estimation. We test methods of separating data for independent quantification of boundary values, fluxes, and uncertainty verification. Specifically, we test the hypothesis that observations made in the marine boundary layer or on aircraft at high altitude provide utility for boundary value estimation; that observations made near the surface over the continent provide strong regional scale constraints on emissions estimates; and that retrievals of column averaged mole fractions are useful as constraints on emissions estimates where other observations are sparse.