| 1. |
- Ren, Hong, et al.
(författare)
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Measurement report: Vertical distribution of biogenic and anthropogenic secondary organic aerosols in the urban boundary layer over Beijing during late summer
- 2021
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Ingår i: ATMOSPHERIC CHEMISTRY AND PHYSICS. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:17, s. 12949-12963
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Tidskriftsartikel (refereegranskat)abstract
- Secondary organic aerosol (SOA) plays a significant role in atmospheric chemistry. However, little is known about the vertical profiles of SOA in the urban boundary layer (UBL). This knowledge gap constrains the SOA simulation in chemical transport models. Here, the aerosol samples were synchronously collected at 8, 120, and 260m based on a 325m meteorological tower in Beijing from 15 August to 10 September 2015. Strict emission controls were implemented during this period for the 2015 China Victory Day parade. Here, we observed that the total concentration of biogenic SOA tracers increased with height. The fraction of SOA from isoprene oxidation increased with height, whereas the fractions of SOA from monoterpenes and sesquiterpenes decreased, and 2,3-dihydroxy-4-oxopentanoic acid (DHOPA), a tracer of anthropogenic SOA from toluene oxidation, also increased with height. The complicated vertical profiles of SOA tracers highlighted the need to characterize SOA within the UBL. The mass concentration of estimated secondary organic carbon (SOC) ranged from 341 to 673 ngC m(-3). The increase in the estimated SOC fractions from isoprene and toluene with height was found to be more related to regional transport, whereas the decrease in the estimated SOC from monoterpenes and sesquiterpene with height was more subject to local emissions. Emission controls during the parade reduced SOC by 4 %-35 %, with toluene SOC decreasing more than the other SOC. This study demonstrates that vertical distributions of SOA within the UBL are complex, and the vertical profiles of SOA concentrations and sources should be considered in field and modeling studies in the future.
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| 2. |
- Yue, Siyao, et al.
(författare)
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Brown carbon from biomass burning imposes strong circum-Arctic warming
- 2022
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Ingår i: ONE EARTH. - : Elsevier BV. - 2590-3330 .- 2590-3322. ; 5:3, s. 293-304
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Tidskriftsartikel (refereegranskat)abstract
- Rapid warming in the Arctic has a huge impact on the global environment. Atmospheric brown carbon (BrC) is one of the least understood and uncertain warming agents due to a scarcity of observations. Here, we performed direct observations of atmospheric BrC and quantified its light-absorbing properties during a 2 month circum-Arctic cruise in summer of 2017. Through observation-constrained modeling, we show that BrC, mainly originated from biomass burning in the mid-to high latitudes of the Northern Hemisphere (similar to 60%), can be a strong warming agent in the Arctic region, especially in the summer, with an average radiative forcing of-90 mW m(-2) (similar to 30% relative to black carbon). As climate change is projected to increase the frequency, intensity, and spread of wildfires, we expect BrC to play an increasing role in Arctic warming in the future.
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| 3. |
- Yue, Siyao, et al.
(författare)
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Sources and Radiative Absorption of Water-Soluble Brown Carbon in the High Arctic Atmosphere
- 2019
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 46:24, s. 14881-14891
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Tidskriftsartikel (refereegranskat)abstract
- Brown carbon (BrC) is a source of light-absorbing aerosols. The Arctic is more sensitive to emissions of light-absorbing aerosols than lower latitudes. Knowledge of BrC in a historical period is beneficial to understand its role in a changing climate. Here, we present measurement of water-soluble BrC (WS-BrC) for the Arctic aerosols during late winter-late spring in 1991. Mass absorption coefficient (0.07 +/- 0.04 M/m) and efficiency (0.41 +/- 0.21 m(2)/g) at 365 nm of WS-BrC were lower than those in polluted urban and rural regions. WS-BrC was mainly from biomass burning/combustion (dark winter to mid-March) and marine sources connected with photochemical gas to particle conversion (after polar sunrise to June). Solar radiative absorption of WS-BrC relative to elemental carbon was 5% on average in February to April and surged to 34% after mid-May. This study helps in understanding the role of BrC in the Arctic climate.
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