Full-coverage mapping and spatiotemporal variations of ground-level ozone (O3) pollution from 2013 to 2020 across China

Remote Sensing of Environment, Год журнала: 2021, Номер 270, С. 112775 - 112775

Опубликована: Ноя. 11, 2021

Язык: Английский

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The global impacts of COVID-19 lockdowns on urban air pollution

Elementa Science of the Anthropocene, Год журнала: 2021, Номер 9(1)

Опубликована: Янв. 1, 2021

The coronavirus-19 (COVID-19) pandemic led to government interventions limit the spread of disease which are unprecedented in recent history; for example, stay at home orders sudden decreases atmospheric emissions from transportation sector. In this review article, current understanding influence emission reductions on pollutant concentrations and air quality is summarized nitrogen dioxide (NO2), particulate matter (PM2.5), ozone (O3), ammonia, sulfur dioxide, black carbon, volatile organic compounds, carbon monoxide (CO). first 7 months following onset pandemic, more than 200 papers were accepted by peer-reviewed journals utilizing observations ground-based satellite instruments. Only about one-third literature incorporates a specific method meteorological correction or normalization comparing data lockdown period with prior reference despite importance doing so interpretation results. We use stringency index (SI) as an indicator severity measures show how key pollutants change SI increases. observed decrease NO2 increasing general agreement inventories that account lockdown. Other compounds such O3, PM2.5, CO also broadly covered. Due chemistry O3 PM2.5 concentrations, their responses may not be linear respect primary pollutants. At most sites, we found increased, whereas decreased slightly, SI. Changes other understudied. highlight future research needs emerging sets preview state atmosphere world targeted permanent emissions. Finally, emphasize need effects meteorology, trends, when determining concentrations.

Язык: Английский

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Ground-Level NO₂Surveillance from Space Across China for High Resolution Using Interpretable Spatiotemporally Weighted Artificial Intelligence

Environmental Science & Technology, Год журнала: 2022, Номер 56(14), С. 9988 - 9998

Опубликована: Июнь 29, 2022

Nitrogen dioxide (NO2) at the ground level poses a serious threat to environmental quality and public health. This study developed novel, artificial intelligence approach by integrating spatiotemporally weighted information into missing extra-trees deep forest models first fill satellite data gaps increase availability 49% then derive daily 1 km surface NO2 concentrations over mainland China with full spatial coverage (100%) for period 2019–2020 combining measurements, tropospheric columns derived from TROPOMI OMI, atmospheric reanalysis, model simulations. Our estimates have an average out-of-sample (out-of-city) cross-validation coefficient of determination 0.93 (0.71) root-mean-square error 4.89 (9.95) μg/m3. The seamless high-resolution high-quality dataset "ChinaHighNO2" allows us examine patterns fine scales such as urban–rural contrast. We observed systematic large differences between urban rural areas (28% on average) in NO2, especially provincial capitals. Strong holiday effects were found, declines 22 14% during Spring Festival National Day China, respectively. Unlike North America Europe, there is little difference weekdays weekends (within ±1 μg/m3). During COVID-19 pandemic, decreased considerably gradually returned normal levels around 72nd day after Lunar New Year which about 3 weeks longer than column, implying that former can better represent changes NOx emissions.

Язык: Английский

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Investigation of near-global daytime boundary layer height using high-resolution radiosondes: first results and comparison with ERA5, MERRA-2, JRA-55, and NCEP-2 reanalyses

Atmospheric chemistry and physics, Год журнала: 2021, Номер 21(22), С. 17079 - 17097

Опубликована: Ноя. 24, 2021

Abstract. The planetary boundary layer (PBL) governs the vertical transport of mass, momentum, and moisture between surface free atmosphere, thus determination PBL height (BLH) is recognized as crucial for air quality, weather, climate analysis. Although reanalysis products can provide important insight into global view BLH in a seamless way, observed situ on scale remains poorly understood due to lack high-resolution (1 or 2 s) radiosonde measurements. present study attempts establish near-global climatology at synoptic times (00:00 12:00 UTC) daytime using measurements over 300 sites worldwide period 2012 2019, which then compared against BLHs obtained from four datasets, including ERA5, MERRA-2, JRA-55, NCEP-2. variations exhibit large spatial temporal dependence, result maxima are generally discerned regions such western United States China, balloon launch mostly correspond afternoon. diurnal revealed with peak 17:00 local solar time (LST). most promising product underestimates by around 130 m radiosondes released during daytime. In addition, MERRA-2 well-established has an underestimation 160 m. JRA-55 NCEP-2 might produce considerable additional uncertainties, much larger up 400 largest bias data appears it be attributed maximal afternoon when risen. Statistical analyses further indicate that biases positively associated orographic complexity, well occurrence static instability. To our best knowledge, this presents first radiosonde-derived provides quantitative assessment frequently used products.

Язык: Английский

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Ground-level gaseous pollutants (NO₂, SO₂, and CO) in China: daily seamless mapping and spatiotemporal variations

Atmospheric chemistry and physics, Год журнала: 2023, Номер 23(2), С. 1511 - 1532

Опубликована: Янв. 26, 2023

Abstract. Gaseous pollutants at the ground level seriously threaten urban air quality environment and public health. There are few estimates of gaseous that spatially temporally resolved continuous across China. This study takes advantage big data artificial-intelligence technologies to generate seamless daily maps three major ambient pollutant gases, i.e., NO2, SO2, CO, China from 2013 2020 a uniform spatial resolution 10 km. Cross-validation between our observations illustrated high on basis for surface CO concentrations, with mean coefficients determination (root-mean-square errors) 0.84 (7.99 µg m−3), (10.7 0.80 (0.29 mg respectively. We found COVID-19 lockdown had sustained impacts pollutants, where recovered its normal in around 34th day after Lunar New Year, while SO2 NO2 rebounded more than 2 times slower due emissions residents' increased indoor cooking atmospheric oxidation capacity. Surface reached their peak annual concentrations 21.3 ± 8.8 m−3, 23.1 13.3 1.01 0.29 m−3 2013, then continuously declined over time by 12 %, 55 17 respectively, until 2020. The declining rates were prominent 2017 sharper reductions anthropogenic but have slowed down recent years. Nevertheless, people still suffer high-frequency risk exposure eastern China, almost World Health Organization (WHO) recommended short-term guidelines (AQG) since 2018, benefiting implemented stricter “ultra-low” emission standards. reconstructed dataset will benefit future (especially short-term) pollution environmental health-related studies.

Язык: Английский

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Opportunistic experiments to constrain aerosol effective radiative forcing

Atmospheric chemistry and physics, Год журнала: 2022, Номер 22(1), С. 641 - 674

Опубликована: Янв. 17, 2022

Aerosol-cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due human activities. The nonlinearity cloud-state changes aerosol perturbations make it challenging attribute causality in observed relationships forcing. Using correlations infer can when meteorological variability also drives both and cloud independently. Natural anthropogenic from well-defined sources provide "opportunistic experiments" (also known as natural experiments) investigate ACI cases where may more confidently inferred. These cover a wide range locations spatiotemporal scales, including point such volcanic eruptions or industrial sources, plumes biomass burning forest fires, tracks individual ships shipping corridors. We review different experimental conditions conduct synthesis available satellite datasets field campaigns place these opportunistic experiments on common footing, facilitating new insights clearer understanding key uncertainties Cloud albedo strongly sensitive background conditions. Strong liquid water path increases largely ruled out by averaging across experiments. Opportunistic have significantly improved process-level ACI, but remains unclear how reliably found scaled global level, thus demonstrating need for deeper investigation order improve assessments climate change.

Язык: Английский

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Separating Daily 1 km PM_2.5 Inorganic Chemical Composition in China since 2000 via Deep Learning Integrating Ground, Satellite, and Model Data

Environmental Science & Technology, Год журнала: 2023, Номер 57(46), С. 18282 - 18295

Опубликована: Апрель 28, 2023

Fine particulate matter (PM2.5) chemical composition has strong and diverse impacts on the planetary environment, climate, health. These effects are still not well understood due to limited surface observations uncertainties in model simulations. We developed a four-dimensional spatiotemporal deep forest (4D-STDF) estimate daily PM2.5 at spatial resolution of 1 km China since 2000 by integrating measurements species from high-density observation network, satellite retrievals, atmospheric reanalyses, Cross-validation results illustrate reliability sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), chloride (Cl-) estimates, with high coefficients determination (CV-R2) ground-based 0.74, 0.75, 0.71, 0.66, average root-mean-square errors (RMSE) 6.0, 6.6, 4.3, 2.3 μg/m3, respectively. The three components secondary inorganic aerosols (SIAs) account for 21% 20% 14% (NH4+) total mass eastern China; we observed significant reductions 40-43% between 2013 2020, slowing down 2018. Comparatively, ratio SIA increased 7% across except Beijing nearby areas, accelerating recent years. SO42- been dominant component China, although it was surpassed NO3- some e.g., Beijing-Tianjin-Hebei region 2016. SIA, accounting nearly half (∼46%) mass, drove explosive formation winter haze episodes North Plain. A sharp decline concentrations an increase SIA-to-PM2.5 ratios during COVID-19 lockdown were also revealed, reflecting enhanced oxidation capacity particles.

Язык: Английский

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Abnormally Shallow Boundary Layer Associated With Severe Air Pollution During the COVID‐19 Lockdown in China

Geophysical Research Letters, Год журнала: 2020, Номер 47(20)

Опубликована: Окт. 1, 2020

After the 2020 Lunar New Year, Chinese government implemented a strict nationwide lockdown to inhibit spread of Coronavirus Disease 2019 (COVID-19). Despite abrupt decreases in gaseous emissions caused by record-low anthropogenic activities, severe haze pollution occurred northern China during COVID lockdown. This paradox has attracted attention both public and scientific community. By analyzing comprehensive measurements air pollutants, planetary boundary layer (PBL) height, surface meteorology, we show that episode over coincided with abnormally low PBL which had reduced 45%, triggering strong aerosol-PBL interactions. dynamical processes initiated temperature inversion, Beijing metropolitan area experienced period continuously shallow PBLs unprecedented event provided an experiment showcasing role particular interactions affecting quality.

Язык: Английский

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Technical note: First comparison of wind observations from ESA's satellite mission Aeolus and ground-based radar wind profiler network of China

Atmospheric chemistry and physics, Год журнала: 2021, Номер 21(4), С. 2945 - 2958

Опубликована: Фев. 26, 2021

Abstract. Aeolus is the first satellite mission to directly observe wind profile information on a global scale. After implementing set of bias corrections, data products went public 12 May 2020. However, over China have thus far not been evaluated extensively by ground-based remote sensing measurements. In this study, Mie-cloudy and Rayleigh-clear from measurements are validated against observations radar profiler (RWP) network in China. Based position each RWP site relative closest ground tracks, three matchup categories proposed, comparisons between performed for category separately. The performance does change much categories. On other hand, products, 1 2 found smaller differences compared with 3. This could be due being sufficiently approximate track 2. vertical, similar observations, except winds height range 0–1 km. mean absolute normalized (Rayleigh-clear) components 3.06 (5.45), 2.79 (4.81), 3.32 (5.72) m/s at all orbit times ascending descending times, respectively. indicates that orbits slightly superior those orbits, observation time has minor effect comparison. From perspective spatial differences, consistent most east China, coastal areas where more reliable. Overall, correlation coefficient R component 0.94 (0.81), suggesting good agreement findings give us sufficient confidence assimilating newly released operational weather forecasting

Язык: Английский

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From COVID-19 to future electrification: Assessing traffic impacts on air quality by a machine-learning model

Proceedings of the National Academy of Sciences, Год журнала: 2021, Номер 118(26)

Опубликована: Июнь 21, 2021

Significance We capitalize on large variations of urban air quality during the COVID-19 pandemic and real-time observations traffic, meteorology, pollution in Los Angeles to develop a machine-learning prediction model. Such model can adequately account for nonlinear relationships between emissions, atmospheric chemistry, meteorological factors. Moreover, this enables us identify key drivers air-quality assess effect future traffic-emission controls quality. unambiguously demonstrate that full benefit from fleet electrification cannot be attained if focused only mitigation local vehicle emissions. To continue improve Angeles, off-road emissions those volatile chemical products need more strictly regulated.

Язык: Английский

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