Comparisons with Vertical Profiles (CarbonTracker-CH4)

HFM_01P2: Discrete Sampling Package, aircraft measurements from Harvard Forest, Massachusetts, United States located at 42.5378° N, 72.1714° W and 340.00 masl. Measurements are made by NOAA Earth System Research Laboratory (ESRL) in collaboration with FOUR STAR AVIATION and Boston University. Assimilation statistics for this and other sites are included in the Documentation.

Residuals (simulated - observed) for aircraft profiles at the selected site, shown as a function of date and sample elevation. Units are 10-9 mol mol-1 of CH4 (ppb). Each dot represents one observation. Aircraft data are not currently assimilated in CarbonTracker and therefore provide an independent check of the simulations.

Statistical summary of residuals for aircraft profiles at the specified site, shown as a function of season and elevation. Units are 10-9 mol mol-1 of CH4 (ppb). The top figure shows the post-assimilation residuals (posterior-observed) and the bottom figure shows the residuals with no data assimilation (prior-observed). Aircraft data are not currently assimilated in CarbonTracker so they provide an independent evaluation of the data assimilation. Ideally, the mean of the residuals for the simulations with data assimilation should be near zero. The residuals for the simulations without data assimilation, on the other hand, may show large biases.