Evolving air quality and impact of changing climate

Sanyal, Swarnali

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Description

Title

Evolving air quality and impact of changing climate

Author(s)

Sanyal, Swarnali

Issue Date

2019-04-17

Director of Research (if dissertation) or Advisor (if thesis)

Wuebbles, Donald J.

Doctoral Committee Chair(s)

Wuebbles, Donald J.

Committee Member(s)

• Riemer, Nicole
• Sriver, Ryan
• Liang, Xin-Zhong

Department of Study

Atmospheric Sciences

Discipline

Atmospheric Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

air quality, exceedance events, long-range transport

Abstract

This dissertation focuses on understanding the complex interaction of air quality and climate change using a suit of global climate chemistry model simulation using Community Earth System Model (CESM). The first phase of the research uses the global model simulation to investigate long-range transport of pollutants from North America to Pico Mountaintop Observatory (PMO) in the North Atlantic. HYSPLIT backward trajectories were used to analyze origin of air mass at PMO. The trajectory analyses showed that more than 50% of the air mass reaching PMO originated from North America. The model simulation was compared with the observation data at the site and high pollution events at Pico were correlated with boreal forest fire events in North America. The results of this study indicate that the global model can simulate the observed levels of pollutants and can capture long-range transport events from North America to mid-Atlantic. The result also confirmed that North American outflow is largely responsible for the high pollutant concentration events that have been measured at PMO. The second phase of the research investigated the impact of changing climate on air quality. This study examined exceedances for upper limits of exposure set by environmental policy. The fully coupled model of the Earth’s climate system with interactive atmospheric chemistry was used to examine exceedances for surface ozone and particulate matter < 2.5m (PM2.5) concentrations for high (RCP8.5) and mid-low (RCP4.5) climate projections. Both surface ozone and PM2.5 have severe health risk affecting the human cardio-pulmonary system causing lung and heart diseases. The exceedance events give a measure of the impact of air quality on human health. The study focused on the United States, India and China and megacities within. Overall, the analyses showed that projected air quality improves over the United States under both climate scenarios and that both ozone and particulate matter exceedance events decrease in the future scenarios when compared to present. In the case of China, the exceedance events for both ozone and particulate matter decreases for the mid-low scenario but increases under the high scenario. Both ozone and particulate matter exceedance days increase in the two climate scenarios for India, especially over the northern Gangetic plains. We also find that in the case of ozone, the high ozone concentration days and therefore exceedance events in the future is not only restricted to the warm summer months, but are spreading to spring and winter, with a significantly increasing trend as a result of changes in both climate and projected emissions. In the case of particulate matter exceedance events, we find that even when we don’t consider the crustal matters (dust and sea salt) in total PM2.5 (referred to as anthropogenic PM2.5), the concentrations still exceed the set standards. The last part of the study investigated a special clean energy scenario for the mid-century. In the clean energy scenario, emissions from fossil fuel is reduced to zero in the model simulation at mid-century. This study showed the surface ozone concentration reduced by 30-50% over different regions in summer. Total PM2.5 reduced by 10-20% and anthropogenic PM2.5 reduced by 40-75% especially over South Asia. The results showed that switching to a non-fossil fuel based clean energy system at mid-century improves air quality significantly globally.

Graduation Semester

2019-05

Type of Resource

text

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Copyright 2019 Swarnali Sanyal

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