Evidence for Large Amounts of Brown Carbonaceous Tarballs in the Himalayan Atmosphere

Abstract

Primary brown carbon (BrC) co-emitted with black carbon (BC) from biomass burning is an important light-absorbing carbonaceous aerosol. BC from the Indo-Gangetic Plain can reach the Himalaya region and influence glacial melting and climatic change. However, to date, there is still not sufficient direct evidence for primary BrC in the Himalayan atmosphere. Here, we detected light-absorbing tarballs at microscopic scale collected on the northern slope of the Himalayas. We found that about 28% of thousands of individual particles were tarballs. The median sizes of externally mixed tarballs and internally mixed tarballs were 213 and 348 nm, respectively. Air mass trajectories, satellite detection, and Weather Research and Forecasting model coupled to Chemistry (WRF-Chem) simulations all indicated that these tarballs were emitted from biomass burning in the Indo-Gangetic Plain. A climate model simulation shows a significant heating effect (+0.01–4.06 W/m2) of the tarballs in the Himalayan atmosphere. We conclude that the tarballs from long-range transport can be an important factor in the climatic effect and would correspond to a substantial influence on glacial melting in the Himalaya region.