Pathways for wintertime deposition of anthropogenic light-absorbing particles on the Central Andes cryosphere

Lapere, Rémy; Mailler, Sylvain; Menut, Laurent; Huneeus, Nicolás

doi:10.1016/j.envpol.2020.115901

Cited by 12 publications

(18 citation statements)

References 27 publications

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“…We find that for the village 34% (1 µg m −3 ) of PM 2.5 , on average, is transported from the metropolitan area. This is consistent with the mountain-valley circulation patterns aforementioned, leading to the intrusion of urban air masses deep into the canyon (Lapere et al, 2021). We acknowledge that the estimate of 34% is probably larger than reality since the HTAP inventory does not capture properly local emissions in the village of San Gabriel, which likely dominate the signal, especially with wood burning for residential heating being largely used in such villages in wintertime.…”

Section: Resultssupporting

confidence: 79%

“…As a result, the PM 2.5 emitted in large amounts mostly remain trapped within this shallow mixing layer. Injection of polluted air masses into the lower FT can also occur, through mountain venting, as described in Lapere et al (2021), explaining why residual concentrations of 1 to 5 µg m −3 are observed higher up in the baseline and contribution scenarios at the latitude of Santiago (Fig. 9b and 9c).…”

Section: Advection Processesmentioning

confidence: 86%

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Referee comment on acp-2020-1249

2021

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Central Chile faces atmospheric pollution issues all year long, in relation with elevated concentrations of fine particulate matter during the cold months and tropospheric ozone during the warm season. In addition to public health issues, environmental problems regarding vegetation growth and water supply, as well as meteorological feedback are at stake. Sharp spatial gradients in regional emissions along with a complex geographical situation make for variable and heterogeneous dynamics in the localization and long-range transport of pollutants, with seasonal differences. Based on chemistry-transport modeling with WRF-CHIMERE, this work studies for one winter period and one summer period: (i) the contribution of emissions from the Santiago Metropolitan Area to air pollution in central Chile, (ii) the reciprocal contribution of regional pollutants transported into the Santiago basin. The underlying 3-dimensional advection patterns are investigated. We find that on average for the winter period 5 µg m −3 to 10 µg m −3 of fine particulate matter in Santiago come from regional transport, corresponding to 13% to 15% of average concentrations. In turn, emissions from the Metropolitan Area contribute to 5% to 10% of fine particulate matter pollution as far as 4 • north and 4 • south. Wintertime transport occurs mostly close to the surface.In summertime, exported precursors from Santiago, in combination with mountain-valley circulation dynamics, are found to account for most of ozone formation in the adjacent Andes cordillera and to create a persistent plume of ozone of more than 50 ppb, extending along 80 km horizontally and 1.5 km vertically, and located several hundred meters above ground, slightly north of Santiago. This work constitutes the first description of such an ozone bubble formation mechanism. Emissions of precursors from the capital city also affect daily maxima of surface ozone hundreds of kilometers away. In parallel, cutting emissions of precursors in the Santiago basin results in an increase of surface ozone mixing ratios in its western area. IntroductionMost urban areas in central Chile, including the capital city Santiago, deal with harmful atmospheric concentrations of fine particulate matter (PM 2.5 ) in wintertime (

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Section: Resultssupporting

confidence: 79%

Section: Advection Processesmentioning

confidence: 86%

Referee comment on acp-2020-1249

2021

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“…Again, mountain-valley circulation accounts for this observation; afternoon westerlies blow O 3 precursors, present in large amounts in urban air masses, towards the Andes. The NO x lifetime is a few hours at most, depending on the reactivity of VOCs and NO 2 density (e.g., Laughner and Cohen, 2019), while most VOCs have an atmospheric lifetime of several days (e.g., Monod et al, 2001) so that, on the way, NO x are consumed more than VOCs. Consequently, while urban air is mostly a NO x -rich environment, precursors ratios become more balanced, along with the export, to create more favorable conditions for O 3 formation on reaching less urbanized areas.…”

Section: Summertime Omentioning

confidence: 99%

“…3.2.2). But NO x have a lifetime that is much shorter than most VOCs (e.g., Monod et al, 2001;Laughner and Cohen, 2019), and when the polluted air parcels are lifted up, the ratio becomes more balanced as NO x is consumed closer to the ground. Due to these asymmetric lifetimes and, hence, export, at some point on the vertical profile the ratio becomes favorable (Fig.…”

Section: Advection Processesmentioning

confidence: 99%

Seasonal variation in atmospheric pollutants transport in central Chile: dynamics and consequences

Lapere¹,

Menut²,

Mailler³

et al. 2021

Atmos. Chem. Phys.

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Abstract. Central Chile faces atmospheric pollution issues all year long as a result of elevated concentrations of fine particulate matter during the cold months and tropospheric ozone during the warm season. In addition to public health issues, environmental problems regarding vegetation growth and water supply, as well as meteorological feedback, are at stake. Sharp spatial gradients in regional emissions, along with a complex geographical situation, make for variable and heterogeneous dynamics in the localization and long-range transport of pollutants, with seasonal differences. Based on chemistry–transport modeling with Weather Research Forecasting (WRF)–CHIMERE, this work studies the following for one winter period and one summer period: (i) the contribution of emissions from the city of Santiago to air pollution in central Chile, and (ii) the reciprocal contribution of regional pollutants transported into the Santiago basin. The underlying 3-dimensional advection patterns are investigated. We find that, on average for the winter period, 5 to 10 µg m−3 of fine particulate matter in Santiago come from regional transport, corresponding to between 13 % and 15 % of average concentrations. In turn, emissions from Santiago contribute between 5 % and 10 % of fine particulate matter pollution as far as 500 km to the north and 500 km to the south. Wintertime transport occurs mostly close to the surface. In summertime, exported precursors from Santiago, in combination with mountain–valley circulation dynamics, are found to account for most of the ozone formation in the adjacent Andes cordillera and to create a persistent plume of ozone of more than 50 ppb (parts per billion), extending along 80 km horizontally and 1.5 km vertically, and located slightly north of Santiago, several hundred meters above the ground. This work constitutes the first description of the mechanism underlying the latter phenomenon. Emissions of precursors from the capital city also affect daily maxima of surface ozone hundreds of kilometers away. In parallel, cutting emissions of precursors in the Santiago basin results in an increase in surface ozone mixing ratios in its western area.

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“…It simulates the physical–chemical processes of the different atmospheric pollutants based on emissions from the main anthropogenic sectors: residential, transportation, industry, and energy. This modeling system has been successfully applied to simulate the dispersion of atmospheric pollutants in central and southern Chile as well as the exposure to particulate matter of public transport users [ 27 , 28 , 29 ].…”

Section: Methodsmentioning

confidence: 99%

Long-Term Exposure to Fine and Coarse Particulate Matter and COVID-19 Incidence and Mortality Rate in Chile during 2020

Valdés

Smith

Opazo

et al. 2021

IJERPH

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Background: Several countries have documented the relationship between long-term exposure to air pollutants and epidemiological indicators of the COVID-19 pandemic, such as incidence and mortality. This study aims to explore the association between air pollutants, such as PM2.5 and PM10, and the incidence and mortality rates of COVID-19 during 2020. Methods: The incidence and mortality rates were estimated using the COVID-19 cases and deaths from the Chilean Ministry of Science, and the population size was obtained from the Chilean Institute of Statistics. A chemistry transport model was used to estimate the annual mean surface concentration of PM2.5 and PM10 in a period before the current pandemic. Negative binomial regressions were used to associate the epidemiological information with pollutant concentrations while considering demographic and social confounders. Results: For each microgram per cubic meter, the incidence rate increased by 1.3% regarding PM2.5 and 0.9% regarding PM10. There was no statistically significant relationship between the COVID-19 mortality rate and PM2.5 or PM10. Conclusions: The adjusted regression models showed that the COVID-19 incidence rate was significantly associated with chronic exposure to PM2.5 and PM10, even after adjusting for other variables.

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Pathways for wintertime deposition of anthropogenic light-absorbing particles on the Central Andes cryosphere

Cited by 12 publications

References 27 publications

Referee comment on acp-2020-1249

Referee comment on acp-2020-1249

Seasonal variation in atmospheric pollutants transport in central Chile: dynamics and consequences

Long-Term Exposure to Fine and Coarse Particulate Matter and COVID-19 Incidence and Mortality Rate in Chile during 2020

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