Widespread Biomass Burning Smoke Throughout the Remote Troposphere

• Published in: Nature geoscience Vol. 13; no. 6; pp. 422 - 427
• Main Authors: Froyd, K D, Bian, H, Kupc, A, Williamson, C, Brock, C A, Ray, E, Hornbrook, R S, Hills, A J, Apel, E C, Chin, M, Colarco, P R, Murphy, D M
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center Nature Research 01.06.2020; Nature Publishing Group UK; Nature Publishing Group
• Subjects: 704/106/35; 704/106/35/823; 704/106/35/824; 704/106/694; Aerosol particles; Aerosols; Airborne sensing; Attenuation; Biomass; Biomass burning; Burning; Cloud precipitation; Dilution; Earth and Environmental Science; Earth Sciences; Earth System Sciences; Geochemistry; Geology; Geophysics/Geodesy; Geosciences (General); Global aerosols; Ocean basins; Oceans; Plumes; Precipitation; Radiation; Removal; Smoke; Terrestrial radiation; Troposphere; Smoke Aerosol; Black Carbon; Biomass Burning
• ISSN: 1752-0894; 1752-0908
• DOI: 10.1038/s41561-020-0586-1

Biomass burning emits ~34–41 Tg yr−1 of smoke aerosol to the atmosphere. Biomass burning aerosol directly influences the Earth’s climate by attenuation of solar and terrestrial radiation; however, its abundance and distribution on a global scale are poorly constrained, particularly after plumes dilute into the background remote troposphere and are subject to removal by clouds and precipitation. Here we report global-scale, airborne measurements of biomass burning aerosol in the remote tropo-sphere. Measurements were taken during four series of seasonal flights over the Pacific and Atlantic Ocean basins, each with near pole-to-pole latitude coverage. We find that biomass burning particles in the remote troposphere are dilute but ubiquitous, accounting for one-quarter of the accumulation-mode aerosol number and one-fifth of the aerosol mass. Comparing our obser-vations with a high-resolution global aerosol model, we find that the model overestimates biomass burning aerosol mass in the remote troposphere with a mean bias of >400%, largely due to insufficient wet removal by in-cloud precipitation. After updat-ing the model’s aerosol removal scheme we find that, on a global scale, dilute smoke contributes as much as denser plumes to biomass burning’s scattering and absorption effects on the Earth’s radiation field.