Measurement report: Strong light absorption induced by aged biomass burning black carbon over the southeastern Tibetan Plateau in pre-monsoon season

Abstract. During the pre-monsoon season, biomass burning (BB) activities are intensive in southern Asia. Facilitated by westerly circulation, those BB plumes can be transported to Tibetan Plateau (TP). Black carbon (BC), main aerosol species emissions, is an important climate warming agent, and its absorbing property strongly depends on size distribution mixing state. To elucidate influence of TP, a field campaign was conducted southeast edge TP during season. It found that substantially increased number concentration atmospheric BC particles factor 13 greatly elevated fraction thickly coated from 52 % up 91 %. Those had slightly larger core much thicker coatings than background particles. However, coating mass not evenly distributed with different sizes. The smaller cores were have shell / ratios cores. Besides, affected vertical variation BC's abundance state, resulting higher concentration, fraction, aging degree upper atmosphere. Resulting both increase loading degree, eventually enhanced total light absorption 15, which 21 contributed aging, 79 mass. Particularly, enhancement induced process long-range transport has far exceeded absorption, implicates significant over region.