Reconstructing 1-km-resolution high-quality PM2.5 data records from 2000 to 2018 in China: spatiotemporal variations and policy implications

Remote Sensing of Environment, Journal Year: 2020, Volume and Issue: 252, P. 112136 - 112136

Published: Oct. 30, 2020

Language: Английский

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Aerosol and boundary-layer interactions and impact on air quality

National Science Review, Journal Year: 2017, Volume and Issue: 4(6), P. 810 - 833

Published: Sept. 16, 2017

Abstract Air quality is concerned with pollutants in both the gas phase and solid or liquid phases. The latter are referred to as aerosols, which multifaceted agents affecting air quality, weather climate through many mechanisms. Unlike pollutants, aerosols interact strongly meteorological variables strongest interactions taking place planetary boundary layer (PBL). PBL hosting bulk of lower atmosphere affected by aerosol radiative effects. Both scattering absorption reduce amount solar radiation reaching ground thus sensible heat fluxes that drive diurnal evolution PBL. Moreover, can increase atmospheric stability inducing a temperature inversion result radiation, suppresses dispersion leads further increases concentration Such positive feedback especially strong during severe pollution events. Knowledge crucial for understanding between meteorology. A key question how interacts vertical directions, affects quality. We review major advances measurements, processes their each other complex mechanisms, highlight priorities future studies.

Language: Английский

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A two-pollutant strategy for improving ozone and particulate air quality in China

Nature Geoscience, Journal Year: 2019, Volume and Issue: 12(11), P. 906 - 910

Published: Oct. 14, 2019

Language: Английский

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Assessing the relationship between surface levels of PM2.5 and PM10 particulate matter impact on COVID-19 in Milan, Italy

The Science of The Total Environment, Journal Year: 2020, Volume and Issue: 738, P. 139825 - 139825

Published: June 2, 2020

The novel coronavirus disease (COVID-19) is a highly pathogenic, transmittable and invasive pneumococcal caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which emerged in December 2019 January 2020 Wuhan city, Hubei province, China fast spread later on the middle of February Northern part Italy Europe. This study investigates correlation between degree accelerated diffusion lethality COVID-19 surface air pollution Milan metropolitan area, Lombardy region, Italy. Daily average concentrations inhalable particulate matter (PM) two size fractions PM2.5, PM10 maxima ground level atmospheric pollutants together quality climate variables (daily temperature, relative humidity, wind speed, pressure field Planetary Boundary Layer-PBL height) collected during 1 January–30 April were analyzed. In spite being considered primarily transmitted indoor bioaerosols droplets infected surfaces, or direct human-to-human personal contacts, it seems that high levels urban pollution, weather specific conditions have significant impact increased rates confirmed Total number, New Deaths cases, possible attributed not only to but also outdoor airborne distribution. Our analysis demonstrates strong influence daily averaged concentrations, positively associated with temperature inversely related humidity cases outbreak Milan. Being pandemic (SARS-CoV-2) version, might be ongoing summer higher temperatures low levels. Presently clear if this protein "spike" new involved through attachment mechanisms aerosols infectious agent transmission from reservoir susceptible host some agglomerated areas like is.

Language: Английский

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Contrasting trends of PM2.5 and surface-ozone concentrations in China from 2013 to 2017

National Science Review, Journal Year: 2020, Volume and Issue: 7(8), P. 1331 - 1339

Published: Feb. 27, 2020

Although much attention has been paid to investigating and controlling air pollution in China, the trends of air-pollutant concentrations on a national scale have remained unclear. Here, we quantitatively investigated variation pollutants China using long-term comprehensive data sets from 2013 2017, during which Chinese government made major efforts reduce anthropogenic emission polluted regions. Our results show significant decreasing trend PM2.5 concentration heavily regions eastern with an annual decrease ∼7% compared measurements 2013. The measured decreased SO2, NO2 CO (a proxy for volatile organic compounds) could explain large fraction different As consequence, days significantly corresponding Concentrations aerosol, nitrate, sulfate, ammonium chloride urban Beijing revealed remarkable reduction connecting decreases aerosol precursors chemical components closely. However, surface-ozone showed increasing most stations indicates stronger photochemical pollution. boundary-layer height capital cities no over Beijing-Tianjin-Hebei, Yangtze River Delta Pearl confirmed emissions. demonstrated that was successful particulate matter areas although ozone increased significantly, suggesting more complex mechanism improving quality future.

Language: Английский

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Estimating Ground‐Level PM_2.5 by Fusing Satellite and Station Observations: A Geo‐Intelligent Deep Learning Approach

Geophysical Research Letters, Journal Year: 2017, Volume and Issue: 44(23)

Published: Nov. 22, 2017

Fusing satellite observations and station measurements to estimate ground-level PM2.5 is promising for monitoring pollution. A geo-intelligent approach, which incorporates geographical correlation into an intelligent deep learning architecture, developed PM2.5. Specifically, it considers distance spatiotemporally correlated in a belief network (denoted as Geoi-DBN). Geoi-DBN can capture the essential features associated with from latent factors. It was trained tested data China 2015. The results show that performs significantly better than traditional neural network. cross-validation R increases 0.63 0.94, RMSE decreases 29.56 13.68${\mu}$g/m3. On basis of derived distribution, predicted over 80% Chinese population live areas annual mean greater 35${\mu}$g/m3. This study provides new perspective air pollution large geographic regions.

Language: Английский

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Relationships between the planetary boundary layer height and surface pollutants derived from lidar observations over China: regional pattern and influencing factors

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(21), P. 15921 - 15935

Published: Nov. 7, 2018

Abstract. The frequent occurrence of severe air pollution episodes in China has been a great concern and thus the focus intensive studies. Planetary boundary layer height (PBLH) is key factor vertical mixing dilution near-surface pollutants. However, relationship between PBLH surface pollutants, especially particulate matter (PM) concentration across China, not yet well understood. We investigate this issue at ∼1600 stations using derived from space-borne ground-based lidar, discuss influence topography meteorological variables on PBLH–PM relationship. Albeit correlations are roughly negative for most cases, their magnitude, significance, even sign vary considerably with location, season, conditions. Weak or uncorrelated relationships found over clean regions (e.g., Pearl River Delta), whereas nonlinearly responses PM to evolution polluted North Plain). Relatively strong interactions when shallow high, which typically corresponds wintertime cases. Correlations much weaker highlands than plains regions, may be associated lighter loading higher elevations contributions mountain breezes. horizontal transport considered as well, manifested correlation wind speed whole nation. Strong upwind plays dominant role removing leads obscure relationships. A ventilation rate used jointly consider dispersion, largest impact pollutant accumulation Plain. As such, study contributes improved understanding aerosol–planetary (PBL) our ability forecast pollution.

Language: Английский

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Air pollution characteristics in China during 2015–2016: Spatiotemporal variations and key meteorological factors

The Science of The Total Environment, Journal Year: 2018, Volume and Issue: 648, P. 902 - 915

Published: Aug. 16, 2018

Language: Английский

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Classification of summertime synoptic patterns in Beijing and their associations with boundary layer structure affecting aerosol pollution

Atmospheric chemistry and physics, Journal Year: 2017, Volume and Issue: 17(4), P. 3097 - 3110

Published: Feb. 28, 2017

Abstract. Meteorological conditions within the planetary boundary layer (PBL) are closely governed by large-scale synoptic patterns and play important roles in air quality directly indirectly affecting emission, transport, formation, deposition of pollutants. Partly due to lack long-term fine-resolution observations PBL, relationships between patterns, PBL structure, aerosol pollution Beijing have not been well understood. This study applied obliquely rotated principal component analysis T-mode classify summertime over using National Centers for Environmental Prediction reanalysis from 2011 2014, investigated their with structure combining numerical simulations, measurements surface meteorological variables, soundings, concentration particles diameters less than or equal 2.5 µm, total cloud cover (CLD), data. Among seven identified three types accounted 67 % number cases studied were associated heavy events. These particular characterized high-pressure systems located east southeast at 925 hPa level, which blocked flow seaward, southerly winds that brought polluted southern industrial zone. The horizontal transport pollutants induced forcings may be most factor summer. In vertical dimension, these featured a relatively low height (BLH) afternoon, accompanied high CLD cold advection seas PBL. reduced solar radiation reaching surface, suppressed thermal turbulence, leading lower BLH. Besides, sensitive experiments show forcing cooled an increase near-surface stability decrease BLH afternoon. Moreover, when warm appeared simultaneously above top level inversion capping strengthened, resulting further suppression thus deterioration levels. has implications understanding crucial factors (at both local scales) modulating forecasting its surrounding area.

Language: Английский

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Impact of diurnal variability and meteorological factors on the PM2.5 - AOD relationship: Implications for PM2.5 remote sensing

Environmental Pollution, Journal Year: 2016, Volume and Issue: 221, P. 94 - 104

Published: Nov. 23, 2016

PM2.5 retrieval from space is still challenging due to the elusive relationship between and aerosol optical depth (AOD), which further complicated by meteorological factors. In this work, we investigated diurnal cycle of in China, using ground-based PM measurements obtained at 226 sites China Atmosphere Watch Network during period January 2013 December 2015. Results showed that nearly half witnessed a maximum morning, contrast least frequent occurrence (5%) afternoon when strong solar radiation received surface results rapid vertical diffusion aerosols thus lower mass concentration. tends peak equally morning evening North Plain (NCP) with an amplitude twice or three times Pearl River Delta (PRD), whereas dominates Yangtze (YRD) magnitude lying those NCP PRD. The gridded correlation maps reveal varying correlations around each site, depending on locations seasons. Concerning impact variation correlation, averaging schemes 3-h, 5-h, 24-h time windows tend have larger R biases, compared scheme 1-h window, indicating plays significant role establishment explicit AOD. addition, high cloud fraction relative humidity weaken regardless geographical location. Therefore, meteorology could be one most plausible alternatives explaining values observed, its non-negligible effect MODIS AOD retrievals. Our findings implications for remote sensing, as long cycle, along meteorology, are explicitly considered future.

Language: Английский

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