Aeolian transport of aerosol black carbon from China to the ocean

Abstract To investigate long-range transport of aerosol black carbon (BC) from China to the downwind seas and ocean, BC concentrations were measured in Beijing city, at a rural station near Beijing city, and at a rural station near Shanghai, for information about source strengths. Aerosol samples were also collected on board research ships in four cruises over the East China Sea and Western Pacific Ocean to determine BC distribution. The data were used to verify a simple one-dimensional transport model. In the marine boundary layer with prevailing westerlies of 5 ms −1 , the BC total deposition rate, including both dry deposition and wet deposition, was computed as −1 × 10 −5 s −1 , and the half-life was estimated to be 19 h. The residence time was approximately 5 d, concentrations subsequently diminishing to the background level. Longer lifetime and farther transport would be probable in the free troposphere. Because BC particles have great surface areas and are very absorbent of electromagnetic waves, their concentration and distribution in the atmosphere may have profound effects on radiation budgets and climate change.