We find that the observed CH4 concentration enhancements and CH4-C2H6-CO correlations in Asian outflow in TRACE-P are determined mainly by anthropogenic emissions from East Asia and Eurasia (defined here as Europe + eastern Russia), with only little contribution from tropical sources (wetlands and biomass burning). The a priori inventory from Wang et al. [2004] overestimates the observed CH4 enhancements and shows regionally variable biases for the CH4/C2H6slope. The CH4/CO slopes are simulated without significant bias. To correct the positive model bias of CH4 concentrations in Chinese boundary layer outflow while increasing the CH4/C2H6 slope and maintaining the CH4/CO slope, we find that we need to increase the East Asian and decrease the Eurasian anthropogenic sources of CH4 by at least 30% for both. Above panel shows the correlations of CH4 with C2H6 and CO in the Chinese boundary layer outflow using the a priori emission (green) and optimized emission inventory (red) as compared to the observations (black). This work was led by Yaping Xiao and a full account is given in Xiao et al. [2004].