Snow cover sensitivity to black carbon deposition in the Himalaya: from atmospheric and ice core measurements to regional climate simulations.

We applied a climate-chemistry model to evaluate the impact of black carbon (BC) deposition on the Himalayan snow cover from 1998 to 2008. Using a stretched grid with a resolution of 50 km over this complex topography, the model reproduces reasonably well the observations of both the snow cover duration and the seasonal cycle of the atmospheric BC concentration including a maximum in atmospheric BC during the pre-monsoon period. Comparing the simulated BC concentrations in the snow with observations is challenging because of the high spatial variability and the complex vertical distribution of BC in the snow. We estimate that both wet and dry BC depositions affect the Himalayan snow cover reducing its annual duration by one to eight days. The resulting increase of the net shortwave radiation at the surface reaches an annual mean of 1 to 3Wm^-2, leading to a localised warming of 0.05 to 0.3 °C. [ABSTRACT FROM AUTHOR]