Brown carbon in the continental troposphere: sources, evolution and radiative impacts

Research is beginning to reveal the sources and prevalence of brown carbon (BrC), however, atmospheric transformations and optical significance, including optical importance relative to black carbon (BC) and influence on direct radiative forcing, is less well known. Although the nature of BrC vertical distributions can significantly influence the radiative forcing impacts, very little data exists on BrC levels throughout the troposphere, in part because aerosol optical instruments can only detect BrC when at significant levels relative to BC. Biomass burning is known to be a substantial source for BrC. Aircraft studies as part of the DC3 and SEAC4RS missions provided a unique opportunity to study wildfire BrC emissions from a variety of sources in different locations and altitudes. This talk will focus on filter-extract measurements of BrC in plumes and aged emissions throughout the troposphere. The evolution and optical importance of BrC will be discussed.