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Formation, radiative forcing, and climatic effects of severe regional haze

Lin, Yun and Wang, Yuan and Pan, Bowen and Hu, Jiaxi and Guo, Song and Levy Zamora, Misti and Tian, Pengfei and Su, Qiong and Ji, Yuemeng and Zhao, Jiayun and Gomez-Hernandez, Mario and Hu, Min and Zhang, Renyi (2022) Formation, radiative forcing, and climatic effects of severe regional haze. Atmospheric Chemistry and Physics, 22 (7). pp. 4951-4967. ISSN 1680-7324. doi:10.5194/acp-22-4951-2022.

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Severe regional haze events, which are characterized by exceedingly high levels of fine particulate matter (PM), occur frequently in many developing countries (such as China and India), with profound implications for human health, weather, and climate. The occurrence of the haze extremes involves a complex interplay between primary emissions, secondary formation, and conducive meteorological conditions, and the relative contributions of the various processes remain unclear. Here we investigated severe regional haze episodes in 2013 over the Northern China Plain (NCP), by evaluating the PM production and the interactions between elevated PM and the planetary boundary layer (PBL). Analysis of the ground-based measurements and satellite observations of PM properties shows nearly synchronized temporal PM variations among the three megacities (Beijing, Baoding, and Shijiazhuang) in this region and a coincidence of the aerosol optical depth (AOD) hotspots with the three megacities during the polluted period. During the clean-to-hazy transition, the measured oxygenated organic aerosol concentration ([OOA]) well correlates with the odd-oxygen concentration ([Oₓ] = [O₃] + [NO₂]), and the mean [OOA]/[Oₓ] ratio in Beijing is much larger than those in other megacities (such as Mexico City and Houston), indicating highly efficient photochemical activity. Simulations using the Weather Research and Forecasting (WRF) model coupled with an explicit aerosol radiative module reveal that strong aerosol–PBL interaction during the polluted period results in a suppressed and stabilized PBL and elevated humidity, triggering a positive feedback to amplify the haze severity at the ground level. Model sensitivity study illustrates the importance of black carbon (BC) in the haze–PBL interaction and the aerosol regional climatic effect, contributing to more than 30 % of the PBL collapse and about half of the positive radiative forcing on the top of the atmosphere. Overall, severe regional haze exhibits strong negative radiative forcing (cooling) of −63 to −88 W m⁻² at the surface and strong positive radiative forcing (warming) of 57 to 82 W m⁻² in the atmosphere, with a slightly negative net radiative forcing of about −6 W m−2 on the top of the atmosphere. Our work establishes a synthetic view for the dominant regional features during severe haze events, unraveling rapid in situ PM production and inefficient transport, both of which are amplified by atmospheric stagnation. On the other hand, regional transport sufficiently disperses gaseous aerosol precursors (e.g., sulfur dioxide, nitrogen oxides, volatile organic compounds, and ammonia) during the clean period, which subsequently result in rapid in situ PM production via photochemistry during the transition period and via multiphase chemistry during the polluted period. Our findings highlight the co-benefits for reduction in BC emissions, which not only improve local and regional air quality by minimizing air stagnation but also mitigate the global warming by alleviating the positive direct radiative forcing.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Lin, Yun0000-0001-8222-0346
Wang, Yuan0000-0001-6657-8401
Pan, Bowen0000-0002-4617-5936
Hu, Jiaxi0000-0002-7795-334X
Guo, Song0000-0002-9661-2313
Levy Zamora, Misti0000-0002-4832-7753
Tian, Pengfei0000-0002-9934-895X
Su, Qiong0000-0003-2420-5898
Ji, Yuemeng0000-0002-8641-4276
Zhao, Jiayun0000-0001-9474-7938
Hu, Min0000-0003-4816-9123
Zhang, Renyi0000-0001-8708-3862
Additional Information:© Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License. Received: 22 Sep 2021 – Discussion started: 29 Oct 2021 – Revised: 16 Feb 2022 – Accepted: 17 Mar 2022 – Published: 14 Apr 2022. The modeling portion of this research was conducted at the TAMU High Performance Research Computing. We thank Hong-Bin Chen and Philippe Goloub for the data at the Beijing AERONET site. This research has been supported by a collaborative program between Texas A&M University (TAMU) and the Natural Science Foundation of China (NSFC). Author contributions. RZ created the original research framework and provided research direction. YL and YW developed the model theory, co-wrote the software, established a database, and created the figures. All authors analyzed the data and co-wrote the manuscript. BP, JH, SG, HM, MZ, and MGH analyzed the PM data; PT provided and processed observed meteorology data; QS, YJ, and JZ provided feedback and contributed to the draft of the manuscript. Code and data availability. The source code of WRF was similar to that described previously by Li et al. (2008) and Fan et al. (2008). All data employed in the present study were described in Sect. 2.1 and are also available from the author (Yun Lin) upon request. The supplement related to this article is available online at: The contact author has declared that neither they nor their co-authors have any competing interests. Review statement. This paper was edited by Zhanqing Li and reviewed by three anonymous referees.
Funding AgencyGrant Number
Texas A&M UniversityUNSPECIFIED
National Natural Science Foundation of ChinaUNSPECIFIED
Issue or Number:7
Record Number:CaltechAUTHORS:20220520-231869000
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Official Citation:Lin, Y., Wang, Y., Pan, B., Hu, J., Guo, S., Levy Zamora, M., Tian, P., Su, Q., Ji, Y., Zhao, J., Gomez-Hernandez, M., Hu, M., and Zhang, R.: Formation, radiative forcing, and climatic effects of severe regional haze, Atmos. Chem. Phys., 22, 4951–4967,, 2022.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114871
Deposited By: George Porter
Deposited On:24 May 2022 14:42
Last Modified:24 May 2022 14:42

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