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University College London (UCL) 2021

Climate Change and Air Pollution Relationships. Lessons from a Subtropical Desert Region (Atacama)

Oyarzun Valenzuela, Damian Esteban

Titre : Climate Change and Air Pollution Relationships. Lessons from a Subtropical Desert Region (Atacama)

Auteur : Oyarzun Valenzuela, Damian Esteban

Université de soutenance : University College London (UCL)

Grade : Doctor of Philosophy (PhD) 2021

The Atacama Desert is the dryest desert on Earth. Atmospheric, ocean, and topographic forcings preserve an exceptional hyper-arid environment. As a product of anthropogenic and natural emissions, PM10 and PM2.5 atmospheric concentrations have been observed to exceed international standards in urban areas where about 1.5 million people live. This research starts by describing the climate dynamics in northern Chile along with the primary anthropogenic emission sources of PM10, PM2.5, and gaseous precursor pollutants. Then, air quality levels across urban areas are evidenced. As a major source of natural PM, the unexplored mineral dust cycle of the Atacama desert is studied from satellite retrievals of aerosols properties. Two areas in the Antofagasta region are identified as predominant sources of dust, where links with reanalysed wind patterns are reported. This study is followed by the analysis of the relationship between PM10-PM2.5 levels and atmospheric ventilation from observational and modelled datasets. Because of the significant link found between both, especially in coastal areas, a wheater-driven model for PM events, with atmospheric ventilation as the most significant input variable, is pro- posed for the coastal city of Antofagasta. Finally, the future of the Atacama Desert, comprising atmospheric and oceanic regional forcings and future PM10-PM2.5 levels, is explored from the UKESM1 model. The South Pacific Anticyclone is already extending and intensifying during the austral summertime. The above leads to increasing upwelling-favourable winds and coastal upwelling intensity of the Humboldt system at the surface ocean, enhancing atmospheric stability. However, a decline is simulated at deeper ocean layers. PM10-PM2.5 are both projected to increase under the SSP370 and SSP585 climate change experiments during the 21st Century. This increasing trend is more abrupt under the SSP370 than the SSP585 experiment due to increased SO2 and dust emissions and the absence of mitigation measurements. Policy implications are dis- cussed, and future academic research is proposed, including implications beyond academia.


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