Date of Award

2025-08-01

Degree Name

Doctor of Philosophy

Department

Environmental Science and Engineering

Advisor(s)

Thomas E. Gill

Abstract

This dissertation explores the interaction between mineral dust and solar radiation in the Chihuahuan Desert, one of the dustiest areas in North America. I focused on two main aspects: (1) the characterization of atmospheric aerosol optical properties during dust events, and (2) the effects of dust deposition (soiling) on the performance of photovoltaic (PV) modules. I characterized the intrinsic optical properties of aerosols in El Paso, Texas during the peak of the 2021 dust season. Ground-level, high-resolution optical and meteorological data were collected at the Black and Brown Carbon (BC^2) study site, whereas particulate matter and additional meteorological parameters were acquired from a collocated air quality monitoring station. PM10, wind speed, and scattering Ångström exponent (SAE) were used as criteria for identification of 27 dust events, predominantly originating from the west-southwest. Their optical characteristics were characterized in terms of SAE, absorption Ångström exponent (AAE) and single scattering albedo (SSA). My findings indicate that the optical properties (SAE, AAE and SSA) of dust at El Paso differ from published values for "pure" dust at other locations, since aerosols during dust events at El Paso were consistently mixed with urban pollution. Moreover, it was found that dust is a constant key component of the aerosols in El Paso even in non-dust-event conditions. The effects of dust deposition on PV systems were assessed using an indoor soiling chamber and a field study at Alamogordo, New Mexico, near the White Sands (WS) dune field. The indoor experiments simulated soiling under various outdoor conditions using five representative types of sand and dust from southwestern North America. Dry (R.H. <30%) and wet (R.H. >90%) deposition methods were employed to evaluate current (IN) losses. Under dry deposition, quartz-dominated dust caused IN losses of 58 - 63%, whereas gypsum dust (WS) produced lower losses (~15.5%). During wet deposition, IN losses of ~81% for Arizona dust were observed. These findings highlight the importance of dust mineralogy and particle size in soiling. During the field study, despite experiencing 22 dust events, soiling losses were low (3% in fall and 2% in spring) compared to other regions. The small soiling losses were attributed to the prevailing south-southwest winds, hitting the front surface of the module, acting as a cleaning mechanism. Rainfall also reduced soiling; as little as 2.2mm of rain was sufficient to restore PV performance. Seasonal variations in dust mineralogy were observed; quartz dominated over the fall and calcite along with WS gypsum being major constituents of the dust during the spring. Mean size of particles collected from the surface of the modules was between 8 and 21 µm, with over 90% dust (<50 µm). Overall, this study helped elucidate the complex interaction between solar radiation and mineral dust in the Chihuahuan Desert by characterizing aerosol optical properties during dust events and assessing dust's subsequent impact after deposition on PV modules. Through field and laboratory experiments, this study identified key factors influencing the interaction between light and dust, including mineral composition, particle size distribution, and meteorological conditions

Language

en

Provenance

Received from ProQuest

File Size

194 p.

File Format

application/pdf

Rights Holder

German Rodriguez Ortiz

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