The impact of biomass burning emissions in Southeast Asia on black carbon aerosols in southern China

Abstract

Since 2013, China's air quality has significantly improved due to the reduction of anthropogenic emissions. The influence of long-distance transport of biomass burning emissions in Southeast Asia (BBSEA) on air quality in southern China (SC) would likely continue to increase, especially under the trend of global warming. We quantify the contribution of BBSEA to the surface and high-altitude BC concentrations in SC (two provincial capitals: Guangzhou (GZ), Guangdong, and Kunming (KM), Yunnan) in March–April 2014 and 2019 by using the GEOS-Chem global chemical transport model and its adjoint. For three severe pollution events in SC in 2014, the contributions of BBSEA to daily average BC concentrations in GZ are 0.08–0.19 μg m⁻³ (2 %–5 %) at the surface and 0.20–0.78 μg m⁻³ (59 %–73 %) at 700 hPa. In KM, the corresponding contributions are 0.27–0.54 μg m⁻³ (15 %–33 %) and 0.25–0.45 μg m⁻³ (28 %–45 %). The transport time of BBSEA to the surface of GZ (KM) is about 3–6 days (1–5 days). The shift in wind fields from southwest to west and stronger wind speeds in April likely shorten the transport time of BBSEA to SC. On March 27, 2019, the relative contributions of BBSEA to the surface BC concentrations increase by 10 % in GZ and 14 % in KM, compared to March 23, 2014. Our study would offer scientific support for understanding BC sources and potential improvement of air quality in SC.