Atmospheric Chemistry and Physics Origin and radiative forcing of black carbon transported to the Himalayas and Tibetan Plateau

Abstract. The remote and high elevation regions of central Asia are influenced by black carbon (BC) emissions from a variety of locations. BC deposition contributes to melting of glaciers and questions exist, of both scientific and policy in-terest, as to the origin of the BC reaching the glaciers. We use the adjoint of the GEOS-Chem model to identify the lo-cation from which BC arriving at a variety of locations in the Himalayas and Tibetan Plateau originates. We then calcu-late its direct and snow-albedo radiative forcing. We analyze the seasonal variation in the origin of BC using an adjoint sensitivity analysis, which provides a detailed map of the lo-cation of emissions that directly contribute to black carbon concentrations at receptor locations. We find that emissions from northern India and central China contribute the majority of BC to the Himalayas, although the precise location varies with season. The Tibetan Plateau receives most BC fro