Date of Award

Spring 1-1-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Peter Pilewskie

Second Advisor

Steven G. Brown

Third Advisor

Katja Friedrich

Abstract

Aerosol particles and their precursor gases have a range of impacts to radiative transfer, the hydrologic cycle, and human health. Understanding aerosol properties and their associated impacts is requisite to knowing what role they play in public health and regional climate. This dissertation examines the impacts of aerosol particles and precursor gases on visibility in the cities of Beijing, China, and New Delhi, India, as well as the performance of particulate matter sensors in the Cuyama Valley of California and Sacramento, California.

Two studies quantify the surface level impact of aerosols on the transfer of visible radiation using publicly available observations of particulate matter, visibility and meteorology in the cities of Beijing and New Delhi. A methodology is presented to empirically estimate the hygroscopic growth rate of particles. The relative impact of dry particulate matter and aerosol bound water on visibility deterioration on seasonal and inter-annual timescales is presented. Long term visibility records are used to reconstruct particulate matter levels, and estimate the long term trends of particulate pollution. Characterizing these aspects of the environment is relevant to policy makers who are interested in improving visibility.

Two studies characterize the performance of sensors that measure particulate matter concentrations using an optical technique in the Cuyama Valley of California and Sacramento, California. The sensors demonstrate a high degree of collocated precision and moderate correlation against reference methods in these environments. The impact of properties including the aerosol size distribution and the ambient relative humidity on sensor accuracy is presented. In the case of Sacramento, the deployment of a network of sensors and the high precision of these sensors provided the opportunity to examine the spatial variability of particulate matter, and estimate the relative exposure of different communities to particulates. We conclude that sensors have the potential to provide valuable information about the spatial-temporal variability of air pollutants.

These results provide insight into the unique environments of study domains, and the methodologies presented can be employed in further cases. They provide new techniques to examine aerosol properties, and their associated impacts, as well as evaluate new measurement technologies.

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