Mixing State of Black Carbon from Biomass Burning Differs Evidently in Different Combustion Phase

Typography

As a short-lived climate forcer, black carbon aerosols in the atmosphere play a vital role in climate change by absorbing solar radiation and altering the formation, lifespan and albedo of clouds. It also provides "seed" for haze formation in urban/regional scale. In northern China, open biomass burning (OBB), such as straw burning after harvesting, is one of important sources of refractory black carbon (rBC). OBB emits both soot particles and substantial amount of semi-volatile organic matters, both of which will undergo a very complicated mixing and evolution processes in the atmosphere to change their ability to form cloud condensation nuclei.

As a short-lived climate forcer, black carbon aerosols in the atmosphere play a vital role in climate change by absorbing solar radiation and altering the formation, lifespan and albedo of clouds. It also provides "seed" for haze formation in urban/regional scale. In northern China, open biomass burning (OBB), such as straw burning after harvesting, is one of important sources of refractory black carbon (rBC). OBB emits both soot particles and substantial amount of semi-volatile organic matters, both of which will undergo a very complicated mixing and evolution processes in the atmosphere to change their ability to form cloud condensation nuclei.

At present, the mixing state of OBB aerosol is usually studied through field studies. Due to influences such as meteorological factors, diffusion and transmission, the mixing state of rBC normally changes significantly with the aging time. In order to better characterize the aging process of rBC, study on the freshly emitted rBC during the whole combustion process is urgently needed. Dr. PAN Xiaole from CAS Institute of Atmospheric Physics and his Japanese collaborators conducted combustion lab experiments to simulate and investigate the rBC emission and mixing state characteristics under different combustion conditions. It was found that the mode diameter of mass size distribution of rBC clearly decreased evidently as combustion state of biomass shifted from flaming-dominant to smoldering-dominant.

Continue reading at Institute of Atmospheric Physics Chinese Academy of Sciences

Image:  The mixing state of rBC during flaming combustion (Left) and smoldering combustion (right).

CREDIT: PAN Xiaole