Shortwave absorption by wildfire smoke dominated by dark brown carbon

Nature Geoscience, Journal Year: 2023, Volume and Issue: 16(8), P. 683 - 688

Published: Aug. 1, 2023

Wildfires emit large amounts of black carbon and light-absorbing organic carbon, known as brown into the atmosphere. These particles perturb Earth's radiation budget through absorption incoming shortwave radiation. It is generally thought that loses its absorptivity after emission in atmosphere due to sunlight-driven photochemical bleaching. Consequently, atmospheric warming effect exerted by remains highly variable poorly represented climate models compared with relatively nonreactive carbon. Given wildfires are predicted increase globally coming decades, it increasingly important quantify these radiative impacts. Here we present measurements ensemble-scale particle-scale smoke plumes from western United States. We find a type dark contributes three-quarters short visible light half long absorption. This strongly absorbing aerosol species water insoluble, resists daytime photobleaching increases night-time processing. Our findings suggest parameterizations need be revised improve estimation forcing associated warming.

Language: Английский

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Rate of atmospheric brown carbon whitening governed by environmental conditions

Proceedings of the National Academy of Sciences, Journal Year: 2022, Volume and Issue: 119(38)

Published: Sept. 12, 2022

Biomass burning organic aerosol (BBOA) in the atmosphere contains many compounds that absorb solar radiation, called brown carbon (BrC). While BBOA is atmosphere, BrC can undergo reactions with oxidants such as ozone which decrease absorbance, or whiten. The effect of temperature and relative humidity (RH) on whitening has not been well constrained, leading to uncertainties when predicting direct radiative climate. Using an flow-tube reactor, we show by oxidation strongly dependent RH temperature. a poke-flow technique, viscosity also depends these conditions. measured rate described data, assuming due occurring bulk BBOA, within thin shell beneath surface. our combined datasets, developed kinetic model this process, lifetime 1 d less below ∼1 km altitude but often much longer than above altitude. Including dependence chemical transport causes large change predicted warming Overall, results illustrate need be considered understand role atmosphere.

Language: Английский

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Modeled and observed properties related to the direct aerosol radiative effect of biomass burning aerosol over the southeastern Atlantic

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(1), P. 1 - 46

Published: Jan. 3, 2022

Abstract. Biomass burning smoke is advected over the southeastern Atlantic Ocean between July and October of each year. This plume overlies mixes into a region persistent low marine clouds. Model calculations climate forcing by this vary significantly in both magnitude sign. NASA EVS-2 (Earth Venture Suborbital-2) ORACLES (ObseRvations Aerosols above CLouds their intEractionS) had deployments for field campaigns off west coast Africa 3 consecutive years (September 2016, August 2017, 2018) with goal better characterizing as function monthly evolution measuring parameters necessary to calculate direct aerosol radiative effect. Here, dataset satellite retrievals cloud properties are used test representation underlying layer two regional models (WRF-CAM5 CNRM-ALADIN) global (GEOS UM-UKCA). The focus on comparisons those that primary determinants effect vertical distribution its properties. representativeness observations averages tested campaign, sampled mean light extinction generally found be within 20 % at altitudes. When compared observations, all models, simulated too vertically diffuse has smaller gradients, UM-UKCA), core displaced lower than observations. Plume carbon monoxide, black carbon, organic masses indicate underestimates modeled concentrations, leading, general, mid-visible optical depth. Biases single scatter albedo positive negative across models. Observed gradients not captured but do capture coarse temporal evolution, correctly simulating higher values (2018) (2017) September (2016). Uncertainties measured absorption Ångstrom exponent were large propagate negligible (<4 %) uncertainty integrated solar and, therefore, biases fraction, scene below plume, four thickness clouds is, average, well WRF-CAM5 ALADIN stratocumulus underestimated GEOS model; UM-UKCA simulates high. Overall, study demonstrates utility repeated, semi-random sampling multiple can give insights model how these affect forcing. combined impact (DARE) estimated using first-order approximation subset five comparison grid boxes. A significant finding observed box average yield (warming) boxes, whereas DARE grid-box-averaged ranges from much larger small, values. It shown quantitatively offset other, so improvements reduce only one property (e.g., fraction) would lead even greater DARE. Across fraction depth contribute largest DARE, also making contribution.

Language: Английский

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Satellite-borne identification and quantification of wildfire smoke emissions in North America via a novel UV-based index

Atmospheric Environment, Journal Year: 2025, Volume and Issue: unknown, P. 121069 - 121069

Published: Jan. 1, 2025

Language: Английский

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Dark brown carbon from biomass burning contributes to significant global-scale positive forcing

One Earth, Journal Year: 2025, Volume and Issue: unknown, P. 101205 - 101205

Published: Feb. 1, 2025

Language: Английский

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Constraining emissions of volatile organic compounds from western US wildfires with WE-CAN and FIREX-AQ airborne observations

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(10), P. 5969 - 5991

Published: May 31, 2023

Abstract. The impact of biomass burning (BB) on the atmospheric burden volatile organic compounds (VOCs) is highly uncertain. Here we apply GEOS-Chem chemical transport model (CTM) to constrain BB emissions in western USA at ∼ 25 km resolution. Across three emission inventories widely used CTMs, inventory–inventory comparison suggests that totals 14 modeled VOC agree with each other within 30 %–40 %. However, for individual VOCs can differ by a factor 1–5, driven regionally averaged ratios (ERs, reflecting both assigned ERs specific biome and vegetation classifications) across inventories. We further evaluate simulations aircraft observations made during WE-CAN (Western Wildfire Experiment Cloud Chemistry, Aerosol Absorption Nitrogen) FIREX-AQ (Fire Influence Regional Global Environments Air Quality) field campaigns. Despite being different global or applying various injection height assumptions, model–observation underpredict observed vertical profiles 3–7. shows small no bias most species low-/no-smoke conditions. thus attribute negative biases mostly underestimated these Tripling reproduces primary compounds, i.e., CO, propane, benzene, toluene. it less significant improvements oxygenated VOCs, particularly formaldehyde, formic acid, acetic lumped ≥ C3 aldehydes, suggesting missing secondary sources BB-impacted environments. underestimation likely attributable underpredicted amounts effective dry matter burned, rather than errors fire detection, height, ERs, as constrained ground measurements. cannot rule out potential sub-grid uncertainties (i.e., not able fully resolve plumes) nested which could explain partially, though back-of-the-envelope calculation evaluation using longer-term measurements help support argument burned underestimation. total implemented only account half 161 measured (∼ 75 versus 150 ppb ppm−1). This reveals amount reactive carbon Considering (× 3) unmodeled 2), infer contributed 10 % 2019 45 2018 (240 2040 Gg C) flux two seasons, compared 1 %–10 standard GEOS-Chem.

Language: Английский

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Phase Behavior and Viscosity in Biomass Burning Organic Aerosol and Climatic Impacts

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(39), P. 14548 - 14557

Published: Sept. 20, 2023

Smoke particles generated by burning biomass consist mainly of organic aerosol termed (BBOA). BBOA influences the climate scattering and absorbing solar radiation or acting as nuclei for cloud formation. The viscosity phase behavior (i.e., number type phases present in a particle) are properties that expected to impact several climate-relevant processes but remain highly uncertain. We studied using fluorescence microscopy showed comprise two (a hydrophobic hydrophilic phase) across wide range atmospheric relative humidity (RH). determined at room temperature photobleaching method possess different RH-dependent viscosities. is largely independent RH from 0 95%. use Vogel–Fulcher–Tamman equation extrapolate our results colder warmer temperatures, based on extrapolation, predicted be glassy (viscosity >1012 Pa s) temperatures less than 230 K RHs below 95%, with possible implications heterogeneous reaction kinetics formation atmosphere. Using kinetic multilayer model (KM-GAP), we investigated effect lifetime brown carbon within BBOA, which climate-warming agent. presence can increase planetary boundary layer polar regions compared previous modeling studies. Hence, lead an warming climate.

Language: Английский

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Identifying the Fraction of Core–Shell Black Carbon Particles in a Complex Mixture to Constrain the Absorption Enhancement by Coatings

Environmental Science & Technology Letters, Journal Year: 2022, Volume and Issue: 9(4), P. 272 - 279

Published: March 18, 2022

The coatings mixing with the refractory black carbon (rBC) may enhance its light absorption (Eabs). Uncertainty largely arises from to what extent can envelope rBC, in addition particle-resolved diversities for rBC size, coatings, and their combinations. Here, by using situ characterization of particle morphology all ambient BC, we propose a single metric well discriminate BC populations without Eabs, which is dynamic shape factor (χ) describe effect nonsphericity enhancing drag force an electrical field compared volume-equivalent sphere (higher χ means more nonspherical). ≤ 1.75 be considered capsulated showing while > not. Given initial increasing causes approach sphericity likely encapsulates thus exerting Eabs. By applying this scenario, are able identify fraction (F) mass Eabs present (likely core–shell) complex mixture (linearly correlated logarithmic coating/rBC volume ratio (VR), parametrized as F = 0.27 × log(VR) + 0.36), predicted bulk improved 36% core–shell only model, capturing transition state when coatings.

Language: Английский

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Brown carbon absorption in the Mediterranean basin from local and long-range transported biomass burning air masses

Atmospheric Environment, Journal Year: 2023, Volume and Issue: 306, P. 119822 - 119822

Published: May 6, 2023

Language: Английский

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Impact of the El Niño on Fire Dynamics on the African Continent

Earth Systems and Environment, Journal Year: 2024, Volume and Issue: 8(1), P. 45 - 61

Published: Jan. 1, 2024

Abstract Several studies investigated the occurrence of fires in Africa with numerical modeling or applied statistics; however, only a few focused on influence El Niño fire risk using coupled model. The study aimed to assess wildfire dynamics SPEEDY-HYCOM events Eastern Tropical Pacific were classified via sea surface temperature (SST) anomaly based predefined climatology between 1961 and 2020 for entire time series SST, obtaining linear anomalies. SST anomalies was created region 5° N S 110° W 170° W. defined three consecutive 3-month periods as weak, moderate, strong conditions. Meteorological Fire Danger Index (MFDI) detect hazards. MFDI simulated by model categories across different lagged months revealed relevant distinctions among categories. In case ‘Weak’, maximum variability observed at lags (0, -3, -6, -9 months) primarily Congo, Gabon, Madagascar. ‘Moderate’ pattern had similar characteristics ‘Weak’ except lag-6 its equatorial zone Africa. ‘Strong’ showed remarkable impact East Africa, resulting high risk, regardless lags. Precipitation evaporation simulations (SPEEDY-HYCOM) indicated that need particular attention central, southern, southeastern regions emphasizing significance lag-0 (evaporation) well lag-0, lag-6, lag-9 (precipitation). conjunction efficient assessing climate variabilities during events. This allows analysis prediction risks events, providing crucial information management prevention. Its uncover significant variations months, contributing understanding mitigation this environmental challenge.

Language: Английский

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