A global 3-D CTM evaluation of black carbon in the Tibetan Plateau
Abstract. We evaluate the black carbon (BC) simulations for 2006 over the Tibetan Plateau by a global 3-D chemical transport model using surface observations of BC in surface air and in snow and BC absorption aerosol optical depth (AAOD). Using updated Asian anthropogenic BC emissions (Lu et al., 2011; Zhang et al., 2009) and global biomass burning emissions (Randerson et al., 2012; van der Werf et al., 2010), model results of both surface BC and BC in snow are statistically in good agreement with observations (biases < 15%). Model results capture the seasonal variation of surface BC concentration, but the observed wintertime high values at rural sites in the Indo-Gangetic Plain are absent in the model. Model results are in general agreement with observations (within a factor of two) at remote sites. Model simulated BC concentrations in snow are spatiotemporally consistent with observations at most sites. We find that modeled BC AAOD are significantly lower than observations to the northwest of the Plateau and along the southern slopes of the Himalayas during winter and spring, reflecting model deficiencies in emissions, topography and BC mixing state. We find that anthropogenic emissions strongly affect surface BC concentration and AAOD, while the BC aging mainly affects BC in snow over the Plateau.