Source attribution of Arctic black carbon and sulfate aerosols and associated Arctic surface warming during 1980–2018

Journal Article · Thu Jul 30 00:00:00 EDT 2020 · Atmospheric Chemistry and Physics (Online)

DOI:https://doi.org/10.5194/acp-20-9067-2020· OSTI ID:1668262

Ren, Lili ^[1]; Yang, Yang  ^[1]; Wang, Hailong ^[2]; Zhang, Rudong ^[2]; Wang, Pinya ^[1]; Liao, Hong ^[1]

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1. Nanjing Univ. of Information Science and Technology, Jiangsu (China). Jiangsu Key Lab. of Atmospheric Environment Monitoring and Pollution Control
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Observations show that the concentrations of Arctic sulfate and black carbon (BC) aerosols have declined since the early 1980s. Previous studies have reported that reducing sulfate aerosols potentially contributed to the recent rapid Arctic warming. In this study, a global aerosol–climate model (Community Atmosphere Model, version 5) equipped with Explicit Aerosol Source Tagging (CAM5-EAST) is applied to quantify the source apportionment of aerosols in the Arctic from 16 source regions and the role of aerosol variations in affecting changes in the Arctic surface temperature from 1980 to 2018. The CAM5-EAST simulated surface concentrations of sulfate and BC in the Arctic had a decrease of 43% and 23%, respectively, in 2014–2018 relative to 1980–1984 mainly due to the reduction of emissions from Europe, Russia and local Arctic sources. Increases in emissions from South and East Asia led to positive trends in Arctic sulfate and BC in the upper troposphere. All aerosol radiative impacts are considered including aerosol–radiation and aerosol–cloud interactions, as well as black carbon deposition on snow- and ice-covered surfaces. Within the Arctic, sulfate reductions caused a top-of-atmosphere (TOA) warming of 0.11 and 0.25 W m^-2 through aerosol–radiation and aerosol–cloud interactions, respectively. While the changes in Arctic atmospheric BC has little impact on local radiative forcing, the decrease in BC in snow and ice led to a net cooling of 0.05 W m^-2. By applying climate sensitivity factors for different latitudinal bands, global changes in sulfate and BC during 2014–2018 (with respect to 1980–1984) exerted a +0.088 and 0.057 K Arctic surface warming, respectively, through aerosol–radiation interactions. Through aerosol–cloud interactions, the sulfate reduction caused an Arctic warming of +0.193 K between the two time periods. The weakened BC effect on snow–ice albedo led to an Arctic surface cooling of -0.041 K. The changes in atmospheric sulfate and BC outside the Arctic produced a total Arctic warming of +0.25 K, the majority of which is due to the midlatitude changes in radiative forcing. Our results suggest that changes in aerosols over the midlatitudes of the Northern Hemisphere have a larger impact on Arctic temperature than other regions through enhanced poleward heat transport. The combined total effects of sulfate and BC produced an Arctic surface warming of +0.297 K, explaining approximately 20% of the observed Arctic warming since the early 1980s.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE; National Natural Science Foundation of China (NSFC); National Key Research and Development Program of China
• Grant/Contract Number: AC05-76RL01830; 41975159; 2019YFA0606800
• OSTI ID: 1668262
• Report Number(s): PNNL-SA-151932
• Journal Information: Atmospheric Chemistry and Physics (Online), Vol. 20, Issue 14; ISSN 1680-7324
• Publisher: European Geosciences Union
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY