The chemical composition and mixing state of  BC-containing particles and the implications  on light absorption enhancement

Sun, Jiaxing; Sun, Yele; Xie, Conghui; Xu, Weiqi; Chen, Chun; Wang, Zhe; Li, Lei; Du, Xubing; Huang, Feifei; Li, Zhijie; Pan, Xiaole; Ma, Nan; Xu, Wanyun; Fu, Pingqing; Wang, Zifa

doi:10.5194/acp-22-7619-2022

Cited by 18 publications

(8 citation statements)

References 68 publications

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“…In the accumulation mode, the new model first enlarges the BC size and limits the BC-containing particle number fraction, which results in a thinner coating. The small BC size, thick coating and 100% proportion of BC-containing particles in the conventional model are not consistent with the observations (Figure 4a) (L. Chen et al, 2020;Sun et al, 2022). First, our new scheme introduces a more realistic and larger BC core size distribution, which results in a lower BC particle number than the total aerosol number in the mode.…”

Section: Bc Microphysical Model In the Abc Modulementioning

confidence: 60%

An Aerosol Optical Module With Observation‐Constrained Black Carbon Properties for Global Climate Models

Chen,

Wang,

Wang

et al. 2023

J Adv Model Earth Syst

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Atmospheric black carbon (BC) aerosols have been long‐lasting uncertain components in environmental and climate studies. Global climate models (GCMs) potentially overestimate BC absorption efficiency due to a lack of consideration of complex BC microphysical and mixing properties. We extract multiple BC properties from observations and develop an aerosol optical module known as Advanced Black Carbon (ABC) in the framework of the Modal Aerosol Model version 4 (MAM4). The ABC module is implemented in the Community Atmosphere Model version 6 (CAM6) and evaluated by in situ and remote sensing observations. CAM6‐ABC addresses the shortcomings of CAM6‐MAM4 in terms of BC microphysical and mixing properties, particularly their size, mixing state and optical simulations. Sensitivity simulations show that the global BC absorption aerosol optical depth at 550 nm simulated by CAM6‐ABC is reduced by ∼29% compared with that in CAM6‐MAM4. The BC absorption enhancement simulated by CAM6‐ABC is reduced from ∼2.6 of the default MAM4 to ∼1.4, which is closer to the observed values (mostly less than 1.5). With improved BC absorption estimation, the biases of aerosol single‐scattering coalbedo simulations are reduced by 18%–69% compared with global Aerosol Robotic Network observations. Moreover, the globally averaged BC direct radiative effect is reduced from 0.37 to 0.28 W/m2 at the top of the atmosphere. Our new scheme alleviates the overestimation of BC absorption in GCMs by constraining BC microphysical and mixing properties when assessing aerosol radiative and climate effects, and it can be easily implemented in most modal‐based aerosol modules of climate models.

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Section: Bc Microphysical Model In the Abc Modulementioning

confidence: 60%

An Aerosol Optical Module With Observation‐Constrained Black Carbon Properties for Global Climate Models

Chen,

Wang,

Wang

et al. 2023

J Adv Model Earth Syst

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“…According to the mass spectral characteristics, temporal trends and size distributions (Dall'osto and Harrison, 2006;Phares et al, 2001), more than 99 % of the total particles were grouped into seven major classes including Total-EC, Total-ECOC, Total-OC, Total-IA, Biomass-K, HOM and Metals, and several subclasses (Table 1). The classification of particles is based on three principles: (1) particles (Sun et al, 2022a;Sun et al, 2022b). The detailed names of particle types and characteristics are given in Table S2, and the average mass spectra of each type of particle are depicted in Figs.…”

Section: Spamsmentioning

confidence: 99%

Mixing state and effective density of aerosol particles during the Beijing 2022 Olympic Winter Games

Sun

Liu

et al. 2023

Preprint

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Abstract. Mixing state and density are two key parameters of aerosol particles affecting their impacts on radiative forcing and human health. Here a single particle aerosol mass spectrometer in tandem with a differential mobility analyzer and an aerodynamic aerosol classifier was deployed during the Beijing 2022 Olympic Winter Games (OWG) to investigate the impacts of emission controls on particle mixing state and density. Nearly 760,000 particles were detected, which were classified into seven major classes. Our results showed the dominance of carbonaceous particles comprising mainly Total-EC (13.4 %), Total-OC (10.5 %) and Total-ECOC (47.1 %). Particularly, the particles containing organic carbon and sulfate were enhanced significantly during OWG although those from primary emissions decreased. The composition of carbonaceous particles also changed significantly which was characterized by the decreases in EC-NS, KEC-N, and amine-containing particles, and increase in ECOC-NS. This result indicates that emission controls during OWG reduced the mixing of elemental carbon (EC) with inorganic aerosol species and amines, yet increased the mixing of EC with organic aerosol. The average effective density (ρeff) of aerosol particles (150–300 nm) was 1.20 g cm−3 with higher values during OWG (1.26 g cm−3) due to the increase in secondary particle contribution. The two types of fresh particles, i.e., Total-EC and high molecular weight organic matter presented the lowest ρeff (0.97 g cm−3 and 0.87 g cm−3, respectively). In addition, the ρeff of most particles increased as the increases in pollution levels and relative humidity, yet varied differently for different types of particles, highlighting the impacts of aging and formation processes on the changes of particle density and mixing state.

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“…Fresh BC particles (BC-fresh) are those freshly emitted without undergoing significant atmospheric processing (Ding et al, 2021). Five types of BC-fresh particles were identified according to the characteristics ion markers: (i) BC-pure is dominated by carbon clusters (C ± n ) with minor ion signals of secondary inorganic species, such as 46[NO2] − and 97[HSO4] − from nitrate and sulfate, respectively (Xie et al, 2020) n , n = 1~4) ion peaks (Yang et al, 2017); (v) BCc particles that are internally mixed with more than one type (BB, CC, and VE) are categorized as Mix type (Sun et al, 2022). S1 and Figure S1 in the Supplement.…”

Section: Bcc Particlesmentioning

confidence: 99%

“…However, this PM2.5 concentration remains significantly higher than the new World Health Organization (WHO) guideline value of 5 μg m -3 (WHO Global Air Quality Guidelines, 2021). Black carbon (BC) is a ubiquitous component of PM2.5 that can mix with various species, and the number fraction of BC-containing particles (BCc) can be higher than 50% of PM2.5 in China (Sun et al, 2022;Xie et al, 2020;. Additionally, the atmospheric aging of BCc involves complex chemical and physical processes, influencing their mixing state, morphology, hygroscopic and optical properties, etc., https://doi.org/10.5194/egusphere-2023-2454 Preprint.…”

Section: Introductionmentioning

confidence: 99%

Measurement report: Characteristics of airborne black carbon-containing particles during the 2021 summer COVID-19 lockdown in Yangzhou, China

Dai,

Wang,

Wang

et al. 2023

Preprint

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Abstract. Black carbon-containing (BCc) particles are pervasive in ambient atmosphere. The unexpected outbreak of the COVID-19 pandemic in 2021 summer prompted a localized and prolonged lockdown in Yangzhou City, situated in the YRD, China, which provides a unique opportunity to gain insights into the relationship between emission sources and BCc. Satellite and ground-level measurements both demonstrated that strict emission controls effectively reduced local gaseous pollutants. Meanwhile, single particle aerosol mass spectrometer (SPA-MS) analysis showed that the number fraction of freshly emitted BCc particles decreased to 28 % during the lockdown (LD), with that from vehicle emissions experiencing the most substantial reduction. However, the uncontrolled reductions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) likely contributed to increased ozone (O3) concentrations, increased the oxidizing capacity, which may in turn enhanced secondary PM2.5 formation and compensated the primary PM2.5 reduction. As a result, we did observe a slight increase of PM2.5 concentration (21.2 μg m-3) during the LD period compared to the period before the lockdown (BLD), and the increase of more aged BCc particles. Reactive trace gases (e.g., NOx, SO2, and VOCs) could form thick coatings on pre-existing particles likely via enhanced heterogeneous hydrolysis under high RH as well, resulting in significant BCc particle growth (~600 nm) during LD period. Furthermore, BCc source apportionment reveals that BCc particles were primarily of local origin (78 %) in Yangzhou during normal summertime. However, coal combustion (23 %) and vehicle emissions (21 %) were prominent non-local pollution sources, with the air mass originating from the southeast, along with biomass burning emissions (19 %) from the northeast, contributing significantly. Our research highlights that short-term, strict local emission controls may not effectively reduce PM pollution, due to the non-linear responses of PM2.5 to its precursors , further effective PM2.5 reduction requires a comprehensive and extensive approach with a regionally coordinated and balanced control strategy through joint regulation.

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The chemical composition and mixing state of BC-containing particles and the implications on light absorption enhancement

Cited by 18 publications

References 68 publications

An Aerosol Optical Module With Observation‐Constrained Black Carbon Properties for Global Climate Models

An Aerosol Optical Module With Observation‐Constrained Black Carbon Properties for Global Climate Models

Mixing state and effective density of aerosol particles during the Beijing 2022 Olympic Winter Games

Measurement report: Characteristics of airborne black carbon-containing particles during the 2021 summer COVID-19 lockdown in Yangzhou, China

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