Author: Rudra Prasad Pokhrel
Publisher:
ISBN: 9781321874884
Category : Atmospheric aerosols
Languages : en
Pages : 78
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Book Description
Optical properties of biomass burning aerosol at three different wavelengths (405, 532, and 660 nm) have been measured during the Fourth Fire Lab at Missoula Experiment (FLAME-4), which took place at the Fire Science Laboratory in Missoula, Montana, in October and November, 2012. During the experiment, absorption and extinction coefficients of aerosol emissions from biomass burning were measured. A photo-acoustic absorption spectrometer (PAS) measured the absorption coefficient of dry and denuded aerosol while a cavity ring-down spectrometer (CRDS) measured the extinction coefficient of dry and denuded aerosol. During the experiment, a wide range of fuels that represent significant sources of biomass emissions from different parts of world were burned. Fuels included trees, grasses, shrubs and peat. Fuels were burned in two different ways namely stack burns which allowed for measurements during different phases of the burn (flaming vs. smoldering) and room burns which allowed for detailed measurements of well mixed smoke from all phases of the fire. Single scattering albedo (SSA) and absorption angstrom exponent (AAE) values for the biomass burning aerosols have been calculated are now represented. Eight fuels were combusted during 20 individual stack burns and 12 fuels were analyzed during 21 room burns. Parameterizations of SSA and AAE as functions of modified combustion efficiency (MCE) and a proxy for the ratio of black carbon to organic carbon mass (BC:OA proxy) have been developed. The BC:OA proxy is found to shown better correlation to both SSA and AAE than does MCE. Combined of the stack and room burn results (41 individual burns and 12 different fuels) show that the BC:OA proxy can explain 94% of the variability in SSA and 70 % of the variability in AAE while MCE can only explain 40 % and 54 % of the variability in SSA and AAE, respectively.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Rudra Prasad Pokhrel
Publisher:
ISBN: 9780355446234
Category : Absorption
Languages : en
Pages : 131
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Book Description
This dissertation examines the optical properties of fresh and aged biomass burning aerosols, parameterization of these properties, and development of new instrumentation and calibration techniques to measure aerosol optical properties. Data sets were collected from the fourth Fire Lab at Missoula Experiment (FLAME-4) that took place from October 15 to November 16, 2012. Biomass collected from the various parts of the world were burned under controlled laboratory conditions and fresh emissions from different stages of burning were measured and analyzed. Optical properties of aged aerosol under different conditions was also explored. A photoacoustic absorption spectrometer (PAS) was built and integrated with a newly designed thermal denuder to improve upon observations made during Flame-4. A novel calibration technique for the PAS was developed. Single scattering albedo (SSA) and absorption Angstrom exponent (AAE) from 12 different fuels with 41 individual burns were estimated and parameterized with modified combustion efficiency (MCE) and the ratio of elemental carbon (EC) to organic carbon (OC) mass. The EC / OC ratio has better capability to parameterize SSA and AAE than MCE. The simple linear regression model proposed in this study accurately predicts SSA during the first few hours of plume aging with the ambient data from a biomass burning event. In addition, absorption due to brown carbon (BrC) can significantly lower the SSA at 405 nm resulting in a wavelength dependence of SSA. Furthermore, smoldering dominated burns have larger AAE values while flaming dominated burns have smaller AAE values indicating a large fraction of BrC is emitted during the smoldering stage of the burn. Enhancement in BC absorption (E[superscript]A[superscript]b[superscript]s) due to coating by absorbing and non-absorbing substances is estimated at 405 nm and 660 nm. Relatively smaller values of E[superscript]A[superscript]b[superscript]s at 660 nm compared to 405 nm suggests lensing is a less important contributor to biomass burning aerosol absorption at lower wavelengths. Multiple burns of the same fuel produced significantly different E[superscript]A[superscript]b[superscript]s values at 405 nm, but show good correlation with the EC/OC ratio indicating less dependency on fuel type and more dependency on burn conditions. In addition, absorption due to BrC can contribute up to 92 % of the total biomass burning aerosol absorption at 405 nm and up to 58 % of the total absorption at 532 nm. Indicating BrC absorption in biomass burning emissions is equally or more important than the absorption due to BC at short wavelengths. Furthermore, fractional absorption due to BrC shows reasonably good correlation with EC/OC ratio and AAE.Primary organic aerosol is found to be more volatile than secondary organic aerosol and it is found that the thermal denuder deployed in this study removes less organic aerosol if secondary organic aerosol is present. SSA at 532 nm remains constant during different conditions of aging while SSA at 405 nm increases under certain conditions suggesting the degradation of BrC. Decreases in AAE under the same experiment further support the proposed BrC degradation. The novel thermal denuder designed completely removes non-refractory material and can be used under higher flow rates (maximum of 5 LPM) than the most commercially available thermal denuders. The new calibration techniques proposed for the photoacousitc absorption spectrometer will reduce uncertainty during calibration compared to the conventional calibration methods.
Author: Sherri W. Hunt
Publisher: ACS Symposium
ISBN: 9780841233638
Category : Science
Languages : en
Pages : 0
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Book Description
This book highlights new cross-disciplinary advances in aerosol chemistry that involve more than one phase, for example, unique chemical processes occurring on gas-solid and liquid-solid interfaces.
Author: Samuel Arthur Whidden
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 0
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Book Description
Author: Joel S. Levine
Publisher: MIT Press
ISBN: 9780262121590
Category : Nature
Languages : en
Pages : 612
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Book Description
This comprehensive volume is the first to consider biomass burning as a global phenomenon and to assess its impact on the atmosphere, on climate, and on the biosphere itself.
Author: Brian Indrek Magi
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 360
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Book Description
Author: Laura E. Mack
Publisher:
ISBN:
Category : Atmospheric aerosols
Languages : en
Pages : 294
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Book Description
Author: Krishna Prasad Vadrevu
Publisher: CRC Press
ISBN: 042966835X
Category : Nature
Languages : en
Pages : 660
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Book Description
The increasing intensity and frequency of natural disasters all around the world has caused severe socioeconomic impacts, especially in South and Southeast Asia. This region is particularly susceptible to vegetation fires, leading to biomass burning pollution with impacts on other countries through trans-boundary air pollution. Despite the growing body of information on biomass pollutants worldwide, only a modest amount of data from these regions are available. With fires and biomass burning identified as a vital issue in South/Southeast Asia, this two-volume set was created to meet community research and application needs. To better serve the atmospheric, environmental, and remote sensing communities, and to address air quality, climate, and the human health impacts of greenhouse gases and aerosols from biomass burning, this set brings together the collective achievements of experts in these regions and the state-of-the-art technologies and spatial analyses to model and monitor biomass burning events and their impacts. This first volume covers various topics on fire, biomass burning, mapping and monitoring while the second volume highlights the impact of biomass burning on the biosphere and reflects extensive research by interdisciplinary teams of experts. This set will serve as a valuable resource for remote sensing scientist, geographers, ecologists, atmospheric scientists, environmental scientists, and all who wish to advance their knowledge on fires, biomass burning, and biomass burning pollution in South/Southeast Asia Specific Features: Unique in its discussion of the sources and the causes of biomass burning and atmospheric research in South and Southeast Asia. Explains how remote sensing and geospatial technologies help the mapping and monitoring of biomass burning events and their impacts. Focuses on large spatial scales integrating top-down and bottom-up methodologies. Addresses the pressing issues of environmental pollution that are rampant in South and Southeast Asia. Includes contributions from global experts currently working on biomass burning projects in the US, Japan, South/Southeast Asia, and Europe.
Author: Joel S. Levine
Publisher: MIT Press
ISBN: 9780262122023
Category : Nature
Languages : en
Pages : 438
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Book Description
Global Biomass Burning provides a convenient and current reference on such topics as the remote sensing of biomass burning from space, the geographical distribution of burning; the combustion products of burning in tropical, temperate, and boreal ecosystems; burning as a global source of atmospheric gases and particulates; the impact of biomass burning gases and particulates on global climate; and the role of biomass burning on biodiversity and past global extinctions."--Pub. desc.
