Observationally Constrained Wintertime Emission Fluxes and Atmospheric Lifetime of Black Carbon in South Asia

High Resolution Image Download MS PowerPoint Slide Black carbon (BC) aerosols perturb the climate and affect air quality/human health. In the highly populated and heavily polluted South Asian region, the wintertime modeled atmospheric abundance of BC has remained underestimated relative to surface observations. We hypothesize this is linked to underestimated (i) atmospheric lifetime (τ BC ) and/or (ii) regional emission fluxes of BC. To address this hypothesis, we developed a novel inversion framework combining multiwinter (2018–2020) hourly resolved BC and carbon monoxide (CO) measurements from a wide footprint site in the North Indian Ocean, intercepting wintertime South Asian outflow. The average ΔBC/ΔCO ratio in this continental outflow of 14 ± 5 ng m –3 ppb –1 was 2–3 times higher than in East Asian outflow and shows a profound regional wintertime presence of BC. The empirically der…