Preprints
https://doi.org/10.5194/acp-2021-921
https://doi.org/10.5194/acp-2021-921

  15 Nov 2021

15 Nov 2021

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

Aerosol indirect effects in complex orography areas: a numerical study over the Great Alpine Region

Anna Napoli1,2, Fabien Desbiolles3,4, Antonio Parodi1, and Claudia Pasquero3,5 Anna Napoli et al.
  • 1CIMA Research Foundation, Savona (Italy)
  • 2Università degli studi di Genova, Genova (Italy)
  • 3Università degli studi di Milano-Bicocca, Milano (Italy)
  • 4Osservatorio Geofisico Sperimentale, Trieste (Italy)
  • 5ISAC-CNR, Torino (Italy)

Abstract. Aerosols play a crucial role in climate through different feedback mechanisms, affecting radiation, clouds and air column stability. This study focuses on the altitude-dependence of the cloud mediated indirect effects of aerosols in the Great Alpine Region (GAR), an area characterised by high pollution levels from anthropic activities in the Po Valley and a complex orography with the highest mountains in Europe. Using a regional atmospheric model, 5-years long convective-permitting sensitivity experiments have been run with different surface aerosol fluxes. The results show that seasonal mean cloud cover, temperature, and precipitations are affected by the aerosol concentrations in the air column, and that the response to pollution is both elevation and season dependent. The overall cloud cover increase with aerosol levels leads to either surface cooling or warming depending on the surface albedo (snow covered or not). Furthermore, different types of clouds have a different sensitivity to aerosols: while the lifetime of low pressure system clouds and orographic clouds is generally increased at high levels of aerosols, convective clouds (typical of the summer season) can actually decrease at high levels of pollution, due to the reduction of strong updrafts.

Anna Napoli et al.

Status: open (until 27 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Anna Napoli et al.

Anna Napoli et al.

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Short summary
Aerosols are liquid or solid particles suspended in the air that can interact with radiation and clouds, modifying the meteoclimatic conditions. Using an atmospheric model, we study the climatological impact of aerosols through their effects on clouds in the Alps, a region characterised by high pollution levels in the densely populated surrounding flatlands. Results show that cloud cover, temperature, and precipitation are affected by aerosols and the response varies with elevation and season.
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