Dissertation
Improving understanding of India’s air pollution from regional and global modeling perspectives
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2022
DOI: 10.17077/etd.006421
Abstract
Air pollution in India leads to more than one million deaths every year. While PM2.5 is the main driver of air pollution and its premature mortality over India, there is a growing awareness of the need to consider both PM2.5 and ozone in the management strategies. The goal of this thesis is to provide a detailed information regarding the state of air quality in India that on one hand helps improving forecasting systems and on the other hand helps decision makers to apply efficient emission control scenarios. In particular, this dissertation includes three air quality modeling studies over India using two different type of numerical models.
First, one extreme air pollution episode in northern India during November 2017 is studied using the Weather Research and Forecasting model with Chemistry (WRF-Chem) regional air quality model. It was found that agricultural waste fires on North West of India were the primary sources of this episode, leading to daily PM2.5 concentrations of more than 800 µg/m3. However, both the magnitudes of emissions and the dynamics of the model led to underestimation of PM2.5 concentrations over Delhi. In particular, it was found that fire emissions could be low by up to a factor of seven for some days. In addition, the effect of changing emissions on planetary boundary layer heights representation and following PM2.5 concentrations downwind was also shown.
Second, India implemented stay-at-home order (i.e. lockdown) on 24 March 2020 to decrease the spread of novel COVID-19, which reduced air pollutant emissions in different sectors. The WRF-Chem model was used to better understand the processes controlling the changes in PM2.5 and ozone in northern India during the COVID-19 lockdown period. It was found that the effect of meteorology and meteorology dependent emissions (e.g. dust and biogenic emissions) were as significant as lockdown anthropogenic emissions on the observed changes in both PM2.5 concentrations. This study also investigated the ozone formation in Delhi and found that ozone concentrations did not drop during the lockdown period as its ozone chemistry is within the VOC-limited regime. Furthermore, the rate of the reactions involved in the ozone formation and destruction pathways over different characteristic regions were extracted to estimate the FNR transition limits, which could be used to infer the ozone formation regime based on satellite formaldehyde and NO2 retrievals.
Finally, the first application of MUlti-Scale Infrastructure for Chemistry and Aerosols – version 0 (MUSICA-v0) earth system model with the capability of refinement to about 14 km horizontal resolution over India for air quality modeling in this region was investigated. The finding was that a refined region (RR) model configuration leads to more dust emissions around India compared with a constant coarse resolution, which improves the PM2.5 concentration results. Furthermore, it was found that less artifact NOx emission dilutions occur in RR configurations due to higher resolution, which leads to more local ozone features over India.
Details
- Title: Subtitle
- Improving understanding of India’s air pollution from regional and global modeling perspectives
- Creators
- Behrooz Roozitalab
- Contributors
- Gregory R. Carmichael (Advisor)Sarath K. Guttikunda (Committee Member)Charles O. Stanier (Committee Member)Simone Tilmes (Committee Member)Jun Wang (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Chemical and Biochemical Engineering
- Date degree season
- Spring 2022
- DOI
- 10.17077/etd.006421
- Publisher
- University of Iowa
- Number of pages
- xv, 198 pages
- Copyright
- Copyright 2022 Behrooz Roozitalab
- Language
- English
- Description illustrations
- Charts, graphs, tables
- Description bibliographic
- Includes bibliographical references (pages 119-135).
- Public Abstract (ETD)
Breathing polluted air is one of the leading causes of deaths globally; most of deaths occur in low-income and middle-income countries. India is one of the most polluted countries of the world, where spatial air quality analysis indicates that 99.9 percent of the Indian population live in air-polluted areas. On the other hand, air quality future projections for India estimate doubling the mortality rate in India, reaching about 2.5 million people in 2050. As a result, government has recently initiated a management plan called National Clean Air Program (NCAP) in order to define the action points to reduce the air pollution in a systematic way. NCAP asks for more studies being done with the objectives ranging from improving public awareness to evolving ambient air quality monitoring and modeling, to implementing mitigation measures. In this dissertation, we studied the regional air quality over India within three studies following the NCAP needs. First, we identified the regional sources of intensive air pollution events during post-monsoon season and the potential reasons for the lack of predictability of the models in capturing their impacts. Second, the chemistry of ozone formation over India and its response to stringent emission control scenarios was investigated. Third, this dissertation introduced the first application of multi-scale earth system models for studying regional air quality over India. The findings of this dissertation provides information that could be used to reduce the air pollution over India.
- Academic Unit
- Chemical and Biochemical Engineering
- Record Identifier
- 9984271054402771
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