Improved 1 km resolution PM_2.5 estimates across China using enhanced space–time extremely randomized trees

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(6), P. 3273 - 3289

Published: March 19, 2020

Abstract. Fine particulate matter with aerodynamic diameters ≤2.5 µm (PM2.5) has adverse effects on human health and the atmospheric environment. The estimation of surface PM2.5 concentrations made intensive use satellite-derived aerosol products. However, it been a great challenge to obtain high-quality high-resolution data from both ground satellite observations, which is essential monitor air pollution over small-scale areas such as metropolitan regions. Here, space–time extremely randomized trees (STET) model was enhanced by integrating updated spatiotemporal information additional auxiliary improve spatial resolution overall accuracy estimates across China. To this end, newly released Moderate Resolution Imaging Spectroradiometer Multi-Angle Implementation Atmospheric Correction AOD product, along meteorological, topographical land-use emissions, input STET model, daily 1 km maps for 2018 covering mainland China were produced. performed well, high out-of-sample (out-of-station) cross-validation coefficient determination (R2) 0.89 (0.88), low root-mean-square error 10.33 (10.93) µg m−3, small mean absolute 6.69 (7.15) m−3 relative 21.28 % (23.69 %). In particular, captured well at regional individual site scales. North Plain, Sichuan Basin Xinjiang Province always featured levels, especially in winter. outperformed most models presented previous related studies, strong predictive power (e.g., monthly R2=0.80), can be used estimate historical records. More importantly, study provides new approach obtaining dataset (i.e., ChinaHighPM2.5), important studies focused urban areas.

Language: Английский

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A Review on Laboratory Studies and Field Measurements of Atmospheric Organic Aerosol Hygroscopicity and Its Parameterization Based on Oxidation Levels

Current Pollution Reports, Journal Year: 2020, Volume and Issue: 6(4), P. 410 - 424

Published: Oct. 6, 2020

Language: Английский

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Estimating daily high-resolution PM2.5 concentrations over Texas: Machine Learning approach

Atmospheric Environment, Journal Year: 2021, Volume and Issue: 247, P. 118209 - 118209

Published: Jan. 14, 2021

Language: Английский

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Significant formation of sulfate aerosols contributed by the heterogeneous drivers of dust surface

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(20), P. 13467 - 13493

Published: Oct. 19, 2022

Abstract. The importance of dust heterogeneous oxidation in the removal atmospheric SO2 and formation sulfate aerosols is not adequately understood. In this study, Fe-, Ti-, Al-bearing components, Na+, Cl−, K+, Ca2+ surface, were discovered to be closely associated with sulfate. Regression models then developed make a reliable prediction reactivity based on particle chemical compositions. Further, recognized gas-phase, aqueous-phase, routes quantitatively assessed kinetically compared by combining laboratory work modelling study. presence 55 µg m−3 airborne dust, accounts for approximately 28.6 % secondary during nighttime, while proportion decreases 13.1 solar irradiation. On drivers (e.g. transition metal constituents, water-soluble ions) are more efficient than surface-adsorbed oxidants H2O2, NO2, O3) conversion SO2, particularly nighttime. Dust offers an opportunity explain missing source severe haze pollution events, its contribution complex environments could even higher current calculation results. Overall, surface responsible significant have profound impacts sulfur cycling.

Language: Английский

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The shifting of secondary inorganic aerosol formation mechanisms during haze aggravation: the decisive role of aerosol liquid water

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(4), P. 2365 - 2378

Published: Feb. 21, 2023

Abstract. Although many considerable efforts have been done to reveal the driving factors on haze aggravation, however, roles of aerosol liquid water (ALW) in secondary inorganic (SIA) formation were mainly focused condition content (ALWC) < 100 µg m−3. Based situ high-resolution field observations, this work studied decisive and shifting mechanisms during revealing different ALWC a broader scale (∼500 m−3) nitrate sulfate induced by aqueous chemistry ammonia-rich atmosphere. The results showed that chemical domains perturbation gas limiting generation particulate matter presented obvious shifts from HNO3-sensitive HNO3- NH3-co-sensitive regime with indicating powerful effects ammonia When 75 m−3, was preferentially triggered high utilization then accelerated nitrogen oxide oxidation clean moderate pollution stages, characterized ratio (NOR) 0.3, sulfur (SOR) 0.4, transition (NTR) 0.7 moral NO3-/SO42-=2:1. > aqueous-phase reaction SO2 NH3 ALW became prerequisite for SIA driven Henry's law atmosphere heavy serious SOR (0.5–0.9), NOR (0.3–0.5) NTR (>0.7), as well NO3-/SO42-=1:1. A positive feedback production also observed due shift partitioning variation aggravation. It implies target controlling should not simply focus NO2, but more attention be paid gaseous precursors (e.g., SO2, NH3) constitution stages.

Language: Английский

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The Influence of Heterogeneous Processes on the Physicochemical Properties of Atmospheric Aerosols

Advances in Atmospheric Sciences, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 22, 2025

Language: Английский

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Current Challenges in Visibility Improvement in Southern China

Environmental Science & Technology Letters, Journal Year: 2020, Volume and Issue: 7(6), P. 395 - 401

Published: April 22, 2020

Stringent emission controls effectively brought down particulate mass concentrations by >30% in the North China Plain (NCP) and Pearl River Delta (PRD) regions. However, low-visibility (<10 km) frequency PRD region barely changed (∼5% decrease Guangzhou), while a of ∼25% was observed NCP. A higher aerosol hygroscopicity scattering efficiency, induced differences chemical composition size distribution, were found compared to NCP, explaining why visibility much worse even under same relative humidity conditions. The unsatisfactory improvement Guangzhou explained substantial increase (47%) optical since 2013. To further improve southern China, aside from secondary inorganic reduction, current challenge mainly lies identifying reducing precursors organic components, whose are highly susceptible changes patterns, for which we urgently need more in-depth studies formation mechanism oxygenated aerosol.

Language: Английский

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Contrasting effects of secondary organic aerosol formations on organic aerosol hygroscopicity

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(13), P. 10375 - 10391

Published: July 9, 2021

Abstract. Water uptake abilities of organic aerosol under sub-saturated conditions play critical roles in direct radiative effects and atmospheric chemistry; however, field characterizations the hygroscopicity parameter κOA remain limited. In this study, a campaign was conducted to characterize at relative humidity 80 % with hourly time resolution for first Pearl River Delta region China. Observation results show that, during campaign, secondary (SOA) dominated total mass (mass fraction > 70 on average), which provides unique opportunity investigate influences SOA formation κOA. Results demonstrate that commonly used oxidation level O/C weakly correlated failed describe variations However, were well reproduced by fractions factor resolved based spectrometer measurements. The more oxygenated (MOOA) factor, exhibiting highest average (∼ 1) among all factors, most important driving increase associated regional air masses. less (LOOA; 0.72) revealed strong daytime production, exerting negative Surprisingly, aged biomass burning (aBBOA) also formed quickly shared similar diurnal pattern LOOA but had much lower (0.39) positive correlation coefficient between aBBOA MOOA reached above 0.8. contrasting volatile compound (VOC) precursors from diverse sources different processes may result chemical composition, functional properties microphysical structure, consequently distinct rendering single parameters (such as O/C) unable capture those differences. Aside observed episodes, suggesting might differ emission conditions. Overall, these highlight it is imperative conduct research characterization meteorological source examine its relationship VOC precursor profiles pathways formulate better develop appropriate parameterization approaches climate models.

Language: Английский

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ISORROPIA-Lite: A Comprehensive Atmospheric Aerosol Thermodynamics Module for Earth System Models

Tellus B, Journal Year: 2022, Volume and Issue: 74(1), P. 1 - 1

Published: March 25, 2022

Aerosol simulations especially for Earth System Models require a thermodynamics module with good compromise between rigor and computational efficiency. We present evaluate ISORROPIA-lite, an accelerated simplified version of the widely used ISORROPIA-II v.2.3 aerosol model, expanded to include effects water uptake from organics updated interface communicating simulation diagnostics information. ISORROPIA-lite assumes is in metastable equilibrium (i.e., salts do not precipitate supersaturated solutions) treats Na⁺–NH₄⁺–SO₄^2––NO₃^––Cl^––Ca²⁺–K⁺–Mg²⁺–Organics–H₂O using binary activity coefficients precalculated look-up tables. Off-line comparison (without organic effects) more than 330,000 atmospherically-relevant states demonstrated that i) provides virtually identical results mode ii) differences stable are less 25% concentrations various semivolatile components similar modes ISORROPIA-II. Using reduced cost by 35% compared online calculation coefficients. Application PMCAMx chemical transport model 3D about 10% changes major 10%. Simulations considering did slow down but increased inorganic at nighttime. Organic could highly contribute total PM₁ mass increase fine nitrate ammonium as much 1 μg m^–3 places where RH levels high.

Language: Английский

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Particle phase state and aerosol liquid water greatly impact secondary aerosol formation: insights into phase transition and its role in haze events

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(4), P. 2399 - 2414

Published: Feb. 26, 2024

Abstract. The particle phase state is crucial for reactive gas uptake, heterogeneous, and multiphase chemical reactions, thereby impacting secondary aerosol formation. This study provides valuable insights into the significance of particle-phase transition liquid water (ALW) in mass growth during winter. Our findings reveal that particles predominantly exist a semi-solid or solid clean winter days with ambient relative humidity (RH) below 30 %. However, non-liquid to occurs when ALW fraction exceeds 15 % (dry mass) at RH thresholds 40 %–60 During haze episodes, transformation rates sulfate nitrate aerosols rapidly increase through increased by 48 11 %, respectively, resulting noticeable increases inorganic (SIA). presence abundant ALW, favored elevated higher proportion SIA, facilitates partitioning water-soluble compounds from phase, as well heterogeneous aqueous processes particles. leads substantial formation organic oxidation. Consequently, overall hygroscopicity parameters exhibit enhancement, mean value 23 These results highlight key factor initiating positive feedback loops between episodes over North China Plain. Accurate predictions necessitate explicit consideration transport models.

Language: Английский

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