Trends in Chemical Composition of Global and Regional Population-Weighted Fine Particulate Matter Estimated for 25 Years

Li, Chi; Martin, Randall V.; Donkelaar, Aaron van; Boys, Brian L.; Hammer, Melanie S.; Xu, Junwei; Marais, Eloïse A.; Reff, Adam; Strum, Madeleine; Ridley, D. A.; Crippa, Monica; Bräuer, Michael; Zhang, Qiang

doi:10.1021/acs.est.7b02530

Cited by 96 publications

(78 citation statements)

References 112 publications

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“…The largest relative change in cloud albedo of 16 % between 2000 and 2017, occurs for the assumption of least soluble particles and the smallest updraft velocity. The high sensitivity for these conditions are expected, since both low updraft and less soluble particles will generate few cloud droplets and thus high sensitivity to even moderate changes in cloud droplet number concentration, all in 30 agreement with Twomey, (1991) and Platnick and Twomey (1994). If we assume that the most realistic composition is somewhere between the 50:50 and 90:10 chemical makeup, this would yield a cloud albedo change in the range of 10-12 %.…”

Section: Trends In Potential Ccn Concentration 25supporting

confidence: 78%

“…Abovementioned air quality policies mainly targeted sulfur emissions which have led to a general decrease in the anthropogenic emissions of SO 2 since the 1970's (Smith et al, 2011;Klimont et al, 2013). With perhaps the exception of the Indian sub-continent, this decrease appears to continue also through the last decade (Li et al, 2017); US EPA, 2018). Zhao et al (2017), showed that the decrease in SO 2 and other important anthropogenic emissions, such as nitrogen oxides 20 and carbonaceous material, is consistent with the decrease in the trends in dimming observed from space borne instruments.…”

Section: Introductionmentioning

confidence: 99%

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On the seasonal variation of observed size distributions in Northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years data from Aspvreten, Sweden

Tunved¹,

Ström²

2019

Preprint

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Abstract. Size resolved aerosol trends were investigate based on a 17-year data set (2000&#8211;2017) from the rural background site Aspvreten located in southern Sweden (58.8&#176;&#8201;N, 17.4&#176;&#8201;E). Cluster analysis of the size distributions was performed to aid in the interpretation of the data. The results confirm previous findings of decreasing aerosol mass during last decades as a result of reduced anthropogenic emissions in Europe. We show that both particle modal number concentration and size substantially has been reduced during last decades. Negative trends in particle number concentration of about 10&#8201;cm&#8722;3&#8201;y&#8722;1 is present for nuclei, Aitken and accumulation modes. In total, integral particle number concentration has decreased by 30&#8201;%, from 1860&#8201;cm&#8722;3 to ca 1300&#8201;cm&#8722;3. This decrease is similar to observations found at other stations in Northern Europe. The reduction in modal number concentration is accompanied by a decrease in modal size, and this decrease is largest for the accumulation mode (2&#8201;nm&#8201;y&#8722;1 or about 17&#8201;% for the whole period). These reductions have resulted in a decrease in submicron particle mass (<&#8201;390&#8201;nm) by more than 50&#8201;% over the period 2000&#8211;2017. Although all size classes show a downward trend as annual averages, we also show that observed trends are not evenly distributed over the year, and that a rather complex picture emerges where both sign and magnitude of trends vary with season and size. The strongest negative trends are present during spring (accumulation mode) and autumn (Aitken mode). The strongest positive trends are present during summer months (Aitken mode). The data analyses do not present evidence for an increase in new particle formation formed locally, although some evidence of increased new particle formation some distance away from the receptor is present. Observed aerosol size distribution data, together with an adiabatic cloud parcel model, was further used to estimate the change in cloud droplet concentration for various assumptions of updraft velocities and aerosol chemical composition. The results indicate a substantial increase in the atmospheric brightening effect due to a reduction in cloud reflectivity corresponding to 10&#8211;12&#8201;% reduction in cloud albedo over the period 2000&#8211;2017.

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Section: Trends In Potential Ccn Concentration 25supporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

On the seasonal variation of observed size distributions in Northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years data from Aspvreten, Sweden

Tunved¹,

Ström²

2019

Preprint

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“…We, thus, present a (non-exhaustive) comparison of the trend results from this study with some other relevant aerosol trend studies in the literature. The Supplement of Li et al (2017) includes a summary of trends reported in the literature for aerosol optical depth (AOD), PM 2.5 and several aerosol constituents (e.g., sulfate, BC).…”

Section: Comparison With Other Trends and Causalitymentioning

confidence: 99%

Multidecadal trend analysis of in situ aerosol radiative properties around the world

et al. 2020

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Abstract. In order to assess the evolution of aerosol parameters affecting climate change, a long-term trend analysis of aerosol optical properties was performed on time series from 52 stations situated across five continents. The time series of measured scattering, backscattering and absorption coefficients as well as the derived single scattering albedo, backscattering fraction, scattering and absorption Ångström exponents covered at least 10 years and up to 40 years for some stations. The non-parametric seasonal Mann–Kendall (MK) statistical test associated with several pre-whitening methods and with Sen's slope was used as the main trend analysis method. Comparisons with general least mean square associated with autoregressive bootstrap (GLS/ARB) and with standard least mean square analysis (LMS) enabled confirmation of the detected MK statistically significant trends and the assessment of advantages and limitations of each method. Currently, scattering and backscattering coefficient trends are mostly decreasing in Europe and North America and are not statistically significant in Asia, while polar stations exhibit a mix of increasing and decreasing trends. A few increasing trends are also found at some stations in North America and Australia. Absorption coefficient time series also exhibit primarily decreasing trends. For single scattering albedo, 52 % of the sites exhibit statistically significant positive trends, mostly in Asia, eastern/northern Europe and the Arctic, 22 % of sites exhibit statistically significant negative trends, mostly in central Europe and central North America, while the remaining 26 % of sites have trends which are not statistically significant. In addition to evaluating trends for the overall time series, the evolution of the trends in sequential 10-year segments was also analyzed. For scattering and backscattering, statistically significant increasing 10-year trends are primarily found for earlier periods (10-year trends ending in 2010–2015) for polar stations and Mauna Loa. For most of the stations, the present-day statistically significant decreasing 10-year trends of the single scattering albedo were preceded by not statistically significant and statistically significant increasing 10-year trends. The effect of air pollution abatement policies in continental North America is very obvious in the 10-year trends of the scattering coefficient – there is a shift to statistically significant negative trends in 2009–2012 for all stations in the eastern and central USA. This long-term trend analysis of aerosol radiative properties with a broad spatial coverage provides insight into potential aerosol effects on climate changes.

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“…However, information regarding the health effects of PM 2.5 components is limited, mainly hindered by the sparse or non-existent coverage of ground PM 2.5 speciation monitors. Meanwhile, the changes in PM 2.5 mass concentrations are driven by the variations of its chemical composition that are related directly to precursor emissions [7,8], thus, understanding the spatiotemporal changes of PM 2.5 speciation also helps designing more effective air pollution mitigation measures.…”

Section: Introductionmentioning

confidence: 99%

Random forest models for PM_2.5 speciation concentrations using MISR fractional AODs

Geng

Meng

et al. 2020

Environ. Res. Lett.

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It is increasingly recognized that various chemical components of PM 2.5 might have differential toxicities to human health, although such studies are hindered by the sparse or non-existent coverage of ground PM 2.5 speciation monitors. The Multi-angle Imaging SpectroRadiometer (MISR) onboard the Terra satellite has an innovative design to provide information about aerosol shape, size and extinction that are more related to PM 2.5 speciation concentrations. In this study, we developed random forest models that incorporated ground measurements of PM 2.5 species, MISR fractional AODs, simulated PM 2.5 speciation concentrations from a chemical transport model (CTM), land use variables and meteorological fields, to predict ground-level daily PM 2.5 sulfate, nitrate, organic carbon (OC) and elemental carbon (EC) concentrations in California between 2005 and 2014. Our models had out-of-bag R 2 of 0.72, 0.70, 0.68 and 0.70 for sulfate, nitrate, OC and EC, respectively. We also conducted sensitivity tests to explore the influence of variable selection on model performance. Results show that if there are sufficient ground measurements and predictor data to support the most sophisticated model structure, fractional AODs and total AOD have similar predicting power in estimating PM 2.5 species. Otherwise, models using fractional AODs outperform those with total AOD. PM 2.5 speciation concentrations are more sensitive to land use variables than other supporting data (e.g., CTM simulations and meteorological information).

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Trends in Chemical Composition of Global and Regional Population-Weighted Fine Particulate Matter Estimated for 25 Years

Cited by 96 publications

References 112 publications

On the seasonal variation of observed size distributions in Northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years data from Aspvreten, Sweden

On the seasonal variation of observed size distributions in Northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years data from Aspvreten, Sweden

Multidecadal trend analysis of in situ aerosol radiative properties around the world

Random forest models for PM_2.5 speciation concentrations using MISR fractional AODs

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Trends in Chemical Composition of Global and Regional Population-Weighted Fine Particulate Matter Estimated for 25 Years

Cited by 96 publications

References 112 publications

On the seasonal variation of observed size distributions in Northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years data from Aspvreten, Sweden

On the seasonal variation of observed size distributions in Northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years data from Aspvreten, Sweden

Multidecadal trend analysis of in situ aerosol radiative properties around the world

Random forest models for PM2.5 speciation concentrations using MISR fractional AODs

Contact Info

Product

Resources

About

Random forest models for PM_2.5 speciation concentrations using MISR fractional AODs