Relative Humidity Modulates the Physicochemical Processing of Secondary Brown Carbon Formation from Nighttime Oxidation of Furan and Pyrrole

ACS ES&T Air, Journal Year: 2024, Volume and Issue: 1(5), P. 426 - 437

Published: April 9, 2024

Light-absorbing secondary organic aerosols (SOAs), also known as brown carbon (BrC), are major components of wildfire smoke that can have a significant impact on the climate system; however, how environmental factors such relative humidity (RH) influence their formation is not fully understood, especially for heterocyclic precursors. We conducted chamber experiments to investigate BrC from nighttime oxidation furan and pyrrole, two primary precursors in wildfires, presence pre-existing particles at RH < 20% ∼ 50%. Our findings revealed increasing significantly affected size distribution dynamics both SOAs, with pyrrole SOA showing stronger potential generate ultrafine via intensive nucleation processes. Higher led increased mass fractions oxygenated compounds suggesting enhanced gas-phase and/or multiphase under humid conditions. Moreover, higher reduced absorption coefficients BrC, contrasting those homocyclic precursors, due non-absorbing high-molecular-weight decreasing molecular chromophores. Overall, our demonstrate unique dependence which may critically modulate radiative effects change.

Language: Английский

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Intense formation of secondary ultrafine particles from Amazonian vegetation fires and their invigoration of deep clouds and precipitation

One Earth, Journal Year: 2024, Volume and Issue: 7(6), P. 1029 - 1043

Published: June 1, 2024

New particle formation (NPF) in fire smoke is thought to be unlikely due large condensation and coagulation sinks that scavenge molecular clusters. We analyze aircraft measurements over the Amazon find fires significantly enhance NPF ultrafine (UFP < 50 nm diameter) numbers compared background conditions, contrary previous understanding. identify nucleation of dimethylamine with sulfuric acid, which aided by extremely low volatility organics biomass-burning smoke, can overcome explain observations. show freshly formed clusters rapidly grow UFP sizes through secondary organic aerosol formation, leading a 10-fold increase number concentrations. contrasting effect UFPs on deep convective clouds larger particles from primary emissions for case investigated here. intensify precipitation increased condensational heating, while delay reduce precipitation.

Language: Английский

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Atmospheric Brown Carbon: Sources, Optical Properties, and Chromophore Composition

Aerosol and Air Quality Research, Journal Year: 2024, Volume and Issue: 24(9), P. 240035 - 240035

Published: Jan. 1, 2024

Brown carbon (BrC) constitutes a significant portion of organic (OC) and exerts substantial influence on air quality, atmospheric chemical processes, the impact climate dynamics. The intricate chemistry BrC arises from multiple mechanisms source types, yielding wide spectrum spectral properties. Consequently, identifying representative chromophore species to develop reference material is crucial capture full diversity found in atmosphere ensure its precise monitoring. This also emphasizes need for more comprehensive measurement method link BrC's optical traits with composition. One objectives this review evaluate existing level understanding concerning molecular compositions compounds by analyzing recent field laboratory data. paper revises expands part prior database containing critical assessments primary secondary sources, photochemistry multi-phase reactions involving BrC, potential candidate chromophores, studies properties cryosphere, draw lessons advances that lead improved representation atmosphere.

Language: Английский

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Modeling actinic flux and photolysis frequencies in dense biomass burning plumes

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(3), P. 1989 - 2015

Published: Feb. 14, 2025

Abstract. Biomass burning (BB) affects air quality and climate by releasing large quantities of gaseous particulate pollutants into the atmosphere. Photochemical processing during daylight transforms these emissions, influencing their overall environmental impact. Accurately quantifying photochemical drivers, namely actinic flux photolysis frequencies, is crucial to constraining this chemistry. However, complex radiative transfer within BB plumes presents a significant challenge for both direct observations numerical models. This study introduces an expanded version 1D VLIDORT-QS (RT) model, named VLIDORT photochemistry (VPC). VPC designed remote sensing applications, particularly in other scenarios. To validate investigate conditions plumes, model was used simulate spatial distributions fluxes frequencies Shady wildfire (Idaho, US, 2019) based on plume composition data from NOAA/NASA FIREX-AQ (Fire Influence Regional Global Environments Air Quality) campaign. Comparison between modeling results CAFS (charged-coupled device spectroradiometer) yields accuracy 10 %–20 %. Systematic biases are 2 %, indicating that uncertainties most likely due variability input caused inhomogeneity as well 3D RT effects not captured model. Random largest ultraviolet (UV) spectral range, where they dominated particle size distribution brown carbon (BrC) absorptive properties. The modeled show decrease top bottom with strong dependence BrC absorption, which darkens towards shorter wavelengths. In visible (Vis) above enhanced up 60 contrast, UV, affected or even reduced Strong reductions exceeding order magnitude below occur ranges but more pronounced UV.

Language: Английский

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Changes in Light Absorption and Chemical Properties for Biomass Burning Organic Aerosol over Long Time Scales

ACS ES&T Air, Journal Year: 2025, Volume and Issue: unknown

Published: April 7, 2025

Language: Английский

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Radiative cooling in New York/New Jersey metropolitan areas by wildfire particulate matter emitted from the Canadian wildfires of 2023

Communications Earth & Environment, Journal Year: 2025, Volume and Issue: 6(1)

Published: April 21, 2025

Wildfire particulate matter from Canadian forest fires significantly impacted the air quality in northeastern United States during summer of 2023. Here, we used real-time and time-integrated instrumentation to characterize physicochemical properties radiative effects wildfire reaching metropolitan areas New Jersey/ York this extreme incident. The forcing -352.4 W/m2 derived here based on measured optical explains, some extent, ground level temperature reduction about 3 °C observed City Such negative densely populated megacities may limit natural ventilation, increase residence time background pollutants, exacerbating public health risks. This study highlights importance their potential implications for climate, health.

Language: Английский

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Anthropogenic Extremely Low Volatility Organics (ELVOCs) Govern the Growth of Molecular Clusters Over the Southern Great Plains During the Springtime

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(21)

Published: Oct. 29, 2024

Abstract New particle formation (NPF) often drives cloud condensation nuclei concentrations and the processes governing nucleation of molecular clusters vary substantially in different regions. The growth these from ∼2 to >10 nm diameters is driven by availability extremely low volatility organic vapors (ELVOCs). Although pathways ELVOC oxidation biogenic terpenes are better understood, mechanistic for anthropogenic organics less well understood. We integrate measurements detailed regional model simulations understand NPF secondary aerosol at Southern Great Plain (SGP) observatory Oklahoma compare with a site within Bankhead National Forest (BNF) Alabama, southeast USA. During our two simulated event days, rates predicted be least an order magnitude higher SGP compared BNF largely due lower sulfuric acid (H 2 SO 4 ) BNF. Among mechanisms WRF‐Chem, we find that dimethylamine (DMA) + H mechanism dominates SGP. ELVOCs critical explaining particles observed Treating as semisolid, strong diffusion limitations vapor uptake phase, brings predictions into closer agreement observations. also simulate non‐NPF days show low‐level clouds reduce photochemical activity corresponding reductions concentrations, thereby lack NPF.

Language: Английский

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Brownness of organics in anthropogenic biomass burning aerosols over South Asia

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(23), P. 13285 - 13297

Published: Dec. 2, 2024

Abstract. In South Asia, biomass is burned for energy and waste disposal, producing brown carbon (BrC) aerosols whose climatic impacts are highly uncertain. To assess these impacts, a real-world understanding of BrC's physio-optical properties essential. For this region, the order-of-magnitude variability in spectral refractive index as function particle volatility distribution poorly understood. This leads to oversimplified model parameterization subsequent uncertainty regional radiative forcing. Here we used field-collected aerosol samples from major anthropogenic activities examine methanol-soluble BrC optical properties. We show strong relation between absorption strength, wavelength dependence, thermo-optical fractions carbonaceous aerosols. Our observations strongly absorbing near Himalayan foothills that may accelerate glacier melt, further highlighting limitations climate models where variable not considered. These findings provide crucial inputs refining developing effective strategies mitigate emissions.

Language: Английский

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Tutorial: A photoacoustic spectrometer to measure aerosol light absorption

Journal of Aerosol Science, Journal Year: 2024, Volume and Issue: unknown, P. 106518 - 106518

Published: Dec. 1, 2024

Language: Английский

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