Worldwide validation of CAMS and MERRA-2 reanalysis aerosol optical depth products using 15 years of AERONET observations

Gueymard, Christian A.; Yang, Di

doi:10.1016/j.atmosenv.2019.117216

Cited by 152 publications

(80 citation statements)

References 127 publications

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“…where " is the known AOD at wavelength (in nm), " ! is the AOD at 1000 nm, and α stands for AE (Gueymard and Yang, 2020).…”

Section: Merra-2 (Modern-era Retrospective Analysis For Research and mentioning

confidence: 99%

“…Despite the dramatic health and socioeconomic consequences of COVID-19 lockdowns, their environmental impact might be beneficial. Bans on mass gatherings, mandatory school closures, and home confinement (He et al, 2020; Le Quéré et al, 2020) during lockdowns have all resulted in lower traffic-related pollutant emissions and improved air quality in Asia, Europe and America (Adams, 2020;Bauwens et al, 2020;Berman and Ebisu, 2020;Conticini et al, 2020;Dantas et al, 2020;Dutheil et al, 2020;He et al, 2020;Kerimray et al, 2020;Lian et al, 2020;Otmani et al, 2020;Sicard et al, 2020;Zheng et al, 2020). The restrictions also present an opportunity to evaluate the cascading responses from the interaction of humans, ecosystems, and climate with the global economy (Diffenbaugh et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Changes in black carbon emissions over Europe due to COVID-19 lockdowns

Evangeliou¹,

Platt²,

Eckhardt³

et al. 2020

Preprint

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Abstract. Following the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for COVID-19 in December 2019 in Wuhan (China) and its spread to the rest of the world, the World Health Organization declared a global pandemic in March 2020. Without effective treatment in the initial pandemic phase, social distancing and mandatory quarantines were introduced as the only available preventative measure. Despite the socioeconomic impacts, air quality improved due to lower pollutant emissions. Here we investigate the effects of the COVID-19 lockdowns on ambient black carbon (BC), which affects climate and damages health, using in-situ observations from 17 European stations in a Bayesian inversion framework. BC emissions declined by 11 % in Europe (20 % in Italy, 32 % in Germany, 20 % in Spain) during lockdown compared to the same period in the previous five years. BC temporal variation in the countries enduring the most drastic restrictions showed the most distinct lockdown impacts. Increased particle light absorption in at the beginning of the lockdown, confirmed by assimilated satellite and remote sensing data, suggests residential combustion was the dominant BC source. Accordingly, in Central and Eastern Europe, which experienced lower than average temperatures, BC was elevated compared to the previous five years. Except for the comparison of BC emissions in the lockdown with the previous five years, an immediate decrease was also seen, as compared with the period before the lockdown, which averaged about 10 % over Europe. Such a decrease was not seen in the previous years, which also confirms an impact on BC emissions from COVID-19.

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“…where " is the known AOD at wavelength (in nm), " ! is the AOD at 1000 nm, and α stands for AE (Gueymard and Yang, 2020).…”

Section: Merra-2 (Modern-era Retrospective Analysis For Research and mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Changes in black carbon emissions over Europe due to COVID-19 lockdowns

Evangeliou¹,

Platt²,

Eckhardt³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…although it may be relevant for aircraft guidance around volcanic ash layers, in cases of visibility reduction during Saharan dust events, for the cloud formation potential or the dispersion of severe 685 pollution events. Our focus on the vertical aerosol distribution complements evaluations based on AOD columns (Rémy et al, 2019;Gueymard and Yang, 2020) and surface in-situ measurements Compared to our first study by CH18, covering the period 09/2015-08/2016, we use the 4 years period 2016-2019 with an overlap of 8 months, use data from 21 instead of 12 ceilometer stations and all evaluable altitudes. As no clear dependence of performance on the distance to model grid points was found in CH18, and the spatial resolution was increased from T255/L60 (≈1…”

Section: Discussionmentioning

confidence: 99%

Evaluation of ECMWF IFS-AER (CAMS) operational forecasts during cycle 41r1 - 46r1 with calibrated ceilometer profiles over Germany

Flentje¹,

Mattis²,

Kipling³

et al. 2020

Preprint

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Abstract. Aerosol forecasts by the European Center for Medium Range Weather Forecasts (ECMWF) Integrated Forecasting System IFS-AER for years 2016–2019 (cycle 41r1 - 46r1) are compared to vertical profiles of particle backscatter from the Deutscher Wetterdienst (DWD) ceilometer network. The system has been developed in the Copernicus Atmosphere Monitoring Service (CAMS) and its precursors. The focus of this article is to evaluate the realism of the vertical aerosol distribution from 0.3 to 8 km above ground, coded in the shape, bias and temporal variation of the profiles. The common physical quantity, the attenuated backscatter β*(z), is directly measured and calculated from the model mass mixing ratios of the different aerosol types using the model's inherent aerosol microphysical properties. Pearson correlation coefficients of daily average simulated and observed vertical profiles between r = 0.6–0.8 in summer and 0.7–0.95 in winter indicate that most of the vertical structure is captured. It is governed by larger β*(z) in the mixing-layer and comparably well captured with the successive model versions. The aerosol load tends to be high-biased near the surface, be underestimated in the mixing layer and realistic at small background values in the undisturbed free troposphere. A seasonal cycle of the bias below 1 km height indicates that aerosol sources and/or lifetimes are overestimated in summer and pollution episodes not fully resolved in winter. Long-range transport of Saharan dust or fire smoke is captured and timely, only the dispersion to smaller scales is not resolved in detail. Over Germany β*(z) from Saharan dust and sea salt are considerably overestimated. Differences between model and ceilometer profiles are investigated using observed in-situ mass concentrations of organic, black carbon, SO4, NO3, NH4 and proxys for mineral dust and sea-salt near the surface. Accordingly, SO4 and OM sources as well as gas-to-particle partitioning of the NO3-NH4-system are too strong. The top of the mixing layer on average appears too smooth and few 100 m too low in the model. Finally, a discussion is included of the considerable uncertainties in the observations, the conversion from modeled to observed physical quantities, and from necessary adaptions of varying resolutions and definitions.

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“…Up to three aerosol layer-top heights (MLHs), calculated by a wavelet algorithm (Teschke and Pönitz, 2010), are reported by the instruments (see next section). Often the uppermost may be identified with the MLH; however, ambiguities in the MLH definition and the different algorithms for its determination remain large (Haeffelin et al, 2012).…”

Section: Ceilometer Networkmentioning

confidence: 99%

“…178) are now in place and used. As a byproduct, the height of the mixing layer (ML) can be inferred from the profiles (Münkel et al, 2007;Haeffelin et al, 2012), which is used by aerosol and chemistry transport models to constrain the vertical exchange and to scale the dispersion of reactive gases and aerosols (Monks et al, 2009) as well as greenhouse gas concentration budgets (Gerbig et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of ECMWF IFS-AER (CAMS) operational forecasts during cycle 41r1–46r1 with calibrated ceilometer profiles over Germany

et al. 2021

View full text Add to dashboard Cite

Abstract. Aerosol forecasts by the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System aerosol module (IFS-AER) for the years 2016–2019 (cycles 41r1–46r1) are compared to vertical profiles of particle backscatter from the Deutscher Wetterdienst (DWD) ceilometer network. The system has been developed in the Copernicus Atmosphere Monitoring Service (CAMS) and its precursors. The focus of this article is to evaluate the realism of the vertical aerosol distribution from 0.4 to 8 km above ground, coded in the shape, bias and temporal variation of the profiles. The common physical quantity, the attenuated backscatter β∗(z), is directly measured and calculated from the model mass mixing ratios of the different particle types using the model's inherent aerosol microphysical properties. Pearson correlation coefficients of daily average simulated and observed vertical profiles between r=0.6–0.8 in summer and 0.7–0.95 in winter indicate that most of the vertical structure is captured. It is governed by larger β∗(z) in the mixing layer and comparably well captured with the successive model versions. The aerosol load tends to be biased high near the surface, underestimated in the mixing layer and realistic at small background values in the undisturbed free troposphere. A seasonal cycle of the bias below 1 km height indicates that aerosol sources and/or lifetimes are overestimated in summer and pollution episodes are not fully resolved in winter. Long-range transport of Saharan dust or fire smoke is captured and timely, only the dispersion to smaller scales is not resolved in detail. Over Germany, β∗(z) values from Saharan dust and sea salt are considerably overestimated. Differences between model and ceilometer profiles are investigated using observed in situ mass concentrations of organic matter (OM), black carbon, SO4, NO3, NH4 and proxies for mineral dust and sea salt near the surface. Accordingly, SO4 and OM sources as well as gas-to-particle partitioning of the NO3–NH4 system are too strong. The top of the mixing layer on average appears too smooth and several hundred meters too low in the model. Finally, a discussion is included of the considerable uncertainties in the observations as well as the conversion from modeled to observed physical quantities and from necessary adaptions of varying resolutions and definitions.

show abstract

Worldwide validation of CAMS and MERRA-2 reanalysis aerosol optical depth products using 15 years of AERONET observations

Cited by 152 publications

References 127 publications

Changes in black carbon emissions over Europe due to COVID-19 lockdowns

Changes in black carbon emissions over Europe due to COVID-19 lockdowns

Evaluation of ECMWF IFS-AER (CAMS) operational forecasts during cycle 41r1 - 46r1 with calibrated ceilometer profiles over Germany

Evaluation of ECMWF IFS-AER (CAMS) operational forecasts during cycle 41r1–46r1 with calibrated ceilometer profiles over Germany

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