Dissertation
Improving the representation of biomass burning in Earth system models
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2022
DOI: 10.17077/etd.006399
Abstract
Biomass burning (BB) is one of the major drivers of climate change. Yearly, fires release thousands of teragrams of gases and aerosols to the atmosphere. BB emissions include diverse aerosol and gaseous species, including greenhouse gases and ozone precursors. Aerosol particles can interact with solar radiation and alter the microphysics and albedo of clouds. Thus, altering the energy budget of the Earth. In addition, large fire events can create poor air-quality conditions that can create health emergencies and interference with human activities when populations are exposed. However, there are still many unknowns related to BB. Because of this, several field experiments have been conducted in recent years in different regions of the world to better understand the nature of fires, quantify their emissions and study the smoke interactions with the other components of the Earth system.
Earth system models (ESMs) are widely use to study and predict the weather and climate, including air-quality. Computational resources have become more accessible in recent years and this trend will continue in the future. Thus, Earth system models (ESMs) can solve detailed chemistry and aerosol mechanisms at very high resolutions. Nonetheless, existent BB emission inventories often provide information on a limited number of species that can alter the results of models. Furthermore, these inventories often provide emissions at resolutions no higher than ~10 km that can result in a misplacement of fires in a fine resolution model grid, which can lead to a misrepresentation of the smoke transport. Aiming to solve this issue, a new BB emission inventory called Visible Infrared Imaging Radiometer Suite (VIIRS)-based Fire Emission Inventory (VFEI) is presented and evaluated. VFEI provides daily emission fluxes for 46 species of aerosols and gases at ~500 m resolution since early 2012 to date. Results show that average global emissions of VFEI are comparable to other major BB emission inventories. Two atmospheric model simulations were conducted using the Weather Research and Forecasting model with Chemistry (WRF-Chem) for Southern Africa and North America. Results showed correlations (r) on simulated aerosol optical depth (AOD) higher than 0.7 in both regions when compared against AOD observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) Multi-Angle Implementation of Atmospheric Correction (MAIAC).
The vertical distribution of smoke in the layers of ESMs are also discussed. Several ESMs include a plume rise model (PRM) that considers the meteorological conditions of the host ESM to estimate the injection height. The first version of PRM used fixed values of heat flux to develop the smoke plume of a fire, but newer versions consider a more individual treatment of fires by using the fire radiative power from remote sensing observations. However, PRM is known to underestimate the injection heights of smoke plumes from large fires. In this thesis we present and discuss different approaches that can be made in PRM to better distribute the BB emissions in the vertical layers. Improvements are suggested to be made into the lateral entrainment parameterization of PRM. Finally, other considerations are discussed, such as the diurnal cycle of fires that need to be better addressed in models for a correct timing on the release of emissions.
Details
- Title: Subtitle
- Improving the representation of biomass burning in Earth system models
- Creators
- Gonzalo Ferrada
- Contributors
- Gregory R. Carmichael (Advisor)Jun Wang (Committee Member)Charles O. Stanier (Committee Member)Scott Spak (Committee Member)Saulo R Freitas (Committee Member) - Instituto Nacional de Pesquisas EspaciaisRavan Ahmadov (Committee Member) - National Oceanic and Atmospheric Administration
- 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.006399
- Publisher
- University of Iowa
- Number of pages
- xvi, 93 pages
- Copyright
- Copyright 2022 Gonzalo Ferrada
- Grants
- NNX15AF95G, National Aeronautics and Space Administration (United States, Washington) - NASANA16OAR4310114, National Oceanic and Atmospheric Administration (United States, Washington) - NOAA
- Grant note
- The author acknowledge the Level-1 and Atmosphere Archive & Distribution System (LAADS) Distributed Active Archive Center (DAAC), located in the Goddard Space Flight Center in Greenbelt, Maryland (https://ladsweb.nascom.nasa.gov/; last access 01 February 2022) from where the VIIRS active fire data was retrieved. I would also like to acknowledge high-performance computing support from Cheyenne (doi:10.5065/D6RX99HX) provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation, where the model simulations from this study were performed.
- Language
- English
- Description illustrations
- illustrations (chiefly color), tables, maps, graphs
- Description bibliographic
- Includes bibliographical references (pages 80-90).
- Public Abstract (ETD)
- Fires are one of the major sources of carbon emissions that promote climate change. Smoke is composed by many gases and particles that can produce poor air-quality conditions and interact with the atmosphere. For example, smoke can interact with solar radiation and formation of clouds. Fire emissions and further smoke processes need to be better represented in Earth system models to better predict weather and climate. During the last decade, the National Aeronautics and Space Administration (NASA) has conducted field experiments in different parts of the world to better understand smoke from fires and its interactions. In this document, we introduce a new fire emission inventory that provides information for 46 different compounds at very high global resolution (around 500 m). This inventory is ideal for fine resolution model grids and sophisticated chemistry schemes. In addition, different formulations to better estimate the altitude that the smoke reaches in the atmosphere are proposed. This last is particularly important, because at higher altitudes winds are stronger and, thus, can transport the smoke far away from its source, enhancing its impacts on the Earth System. With these developments, models can better forecast not only emissions, but also the smoke transport. For example, the long-range transport of smoke from fires in Siberia, the Amazon forest or the Western United States and predict poor air-quality episodes in other populated areas.
- Academic Unit
- Chemical and Biochemical Engineering
- Record Identifier
- 9984270953202771
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