Preprints
https://doi.org/10.5194/acp-2020-1249
https://doi.org/10.5194/acp-2020-1249

  21 Jan 2021

21 Jan 2021

Review status: this preprint is currently under review for the journal ACP.

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

Rémy Lapere1, Laurent Menut1, Sylvain Mailler1,2, and Nicolás Huneeus3 Rémy Lapere et al.
  • 1Laboratoire de Météorologie Dynamique, IPSL, École Polytechnique, Institut Polytechnique de Paris, ENS, Université PSL, Sorbonne Université, CNRS, Palaiseau, France
  • 2École des Ponts, Université Paris-Est, 77455 Champs-sur-Marne, France
  • 3Department of Geophysics, Universidad de Chile, Santiago, Chile

Abstract. 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.

Rémy Lapere et al.

Status: open (until 18 Mar 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1249', Anonymous Referee #3, 16 Feb 2021 reply
  • RC2: 'Referee comment on acp-2020-1249', Anonymous Referee #1, 17 Feb 2021 reply

Rémy Lapere et al.

Rémy Lapere et al.

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Short summary
Based on modeling, the transport dynamics of ozone and fine particles in central Chile are investigated. Santiago emissions are found to influence air quality along a 1000 km plume as far as Argentina and northern Chile. In turn, emissions outside the metropolis contribute significantly to its recorded particles concentration. Emissions of precursors from Santiago are found to lead to the formation of a persistent ozone bubble in altitude, phenomenon which is described for the first time.
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