Microphysical Properties of Black Carbon Aerosol Observed During the ACCLIP Mission

Black carbon (BC) is a primary aerosol formed via incomplete combustion and absorbs light. BC has a significant net positive radiative forcing effect, making it an important parameter for atmospheric models predicting future climate. The Asian Summer Monsoon (ASM) transports aerosols and trace gases from the boundary layer in Southeast Asia and over the Tibetan Plateau to the upper troposphere/lower stratosphere (UTLS) via strong convection. Strong emission sources in this region, including those of BC, linked to transport via the ASM may have important chemical and climate impacts. Indeed, enhanced carbon monoxide from this pathway has been documented from satellite measurements. The Asian Summer Monsoon Chemical and Climate Impact Project (ACCLIP, August 2022) investigated the chemical composition of air transported by the ASM and its impacts on aerosol distributions and characteristics in the UTLS. Here, we use measurements made by the NOAA Single Particle Soot Photometer (SP2), which detects refractory BC mass and the optical size of BC-containing particles, to examine the microphysical properties of BC transported by ASM and its spatial and temporal variations. We present coating thickness and size distributions of BC-containing aerosol in the UTLS, observations which will advance understanding of the impacts of ASM transport processes on BC and on BC's ability to influence radiative forcing in the UTLS.