scholarly journals AN ASSESSMENT OF SEVERITY OF ENVIRONMENTAL AEROSOL PARTICLES DURING PRECIPITATION

2015 ◽  
Vol 4 (3) ◽  
pp. 81-95
Author(s):  
T. S. Verma ◽  
K. S. Madhava Rao ◽  
Shibu K. John
Keyword(s):  
Mathematical Model ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Atmospheric Aerosol ◽  
Aerosol Particles ◽  
Carbon Dioxide Concentration ◽  
Objective Criterion ◽  
Different Seasons ◽  
Index Of Severity ◽  
The Impact

Africa is one of the sources of biomass burning emissions. It is estimated that about 6 million tons of fuel per day is consumed in the southern hemisphere. Biomass burning has an important contribution on aerosol particle concentrations in the atmosphere. Efforts have been made to conduct research in Gaborone to monitor the concentration of atmospheric aerosols in atmosphere. These studies were mainly confined to measurement of concentration of aerosols and establishing a relation with determinants such as carbon dioxide concentration, biomass burning, and precipitation among others. However, very little seems to have been done in relating the empirical data to a mathematical model or to study quantitatively the impact of precipitation on the concentration of aerosols larger than 0.3?m in the atmosphere. In this paper we provide an objective criterion for classifying measurements on concentration of atmospheric aerosol particles and build a mathematical model that helps us to understand variations in weekly aerosol concentrations in terms of their severity. We also construct an index of severity which when applied to different seasons under the study period indicates that precipitation significantly scavenges atmospheric aerosols.International Journal of Environment Volume-4, Issue-3, June-August 2015Page: 81-95

scholarly journals Regional influence of wildfires on aerosol chemistry in the western US and insights into atmospheric aging of biomass burning organic aerosol

2017 ◽  
Vol 17 (3) ◽  
pp. 2477-2493 ◽  
Author(s):  
Shan Zhou ◽  
Sonya Collier ◽  
Daniel A. Jaffe ◽  
Nicole L. Briggs ◽  
Jonathan Hee ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Chemical Transformation ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Global Climate ◽  
Organic Aerosol ◽  
The United States ◽  
Aerosol Composition ◽  
Western Us ◽  
The Impact

Abstract. Biomass burning (BB) is one of the most important contributors to atmospheric aerosols on a global scale, and wildfires are a large source of emissions that impact regional air quality and global climate. As part of the Biomass Burning Observation Project (BBOP) field campaign in summer 2013, we deployed a high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) coupled with a thermodenuder at the Mt. Bachelor Observatory (MBO, ∼  2.8 km above sea level) to characterize the impact of wildfire emissions on aerosol loading and properties in the Pacific Northwest region of the United States. MBO represents a remote background site in the western US, and it is frequently influenced by transported wildfire plumes during summer. Very clean conditions were observed at this site during periods without BB influence where the 5 min average (±1σ) concentration of non-refractory submicron aerosols (NR-PM1) was 3.7 ± 4.2 µg m−3. Aerosol concentration increased substantially (reaching up to 210 µg m−3 of NR-PM1) for periods impacted by transported BB plumes, and aerosol composition was overwhelmingly organic. Based on positive matrix factorization (PMF) of the HR-AMS data, three types of BB organic aerosol (BBOA) were identified, including a fresh, semivolatile BBOA-1 (O ∕ C  =  0.35; 20 % of OA mass) that correlated well with ammonium nitrate; an intermediately oxidized BBOA-2 (O ∕ C  =  0.60; 17 % of OA mass); and a highly oxidized BBOA-3 (O ∕ C  =  1.06; 31 % of OA mass) that showed very low volatility with only  ∼  40 % mass loss at 200 °C. The remaining 32 % of the OA mass was attributed to a boundary layer (BL) oxygenated OA (BL-OOA; O ∕ C  =  0.69) representing OA influenced by BL dynamics and a low-volatility oxygenated OA (LV-OOA; O ∕ C  =  1.09) representing regional aerosols in the free troposphere. The mass spectrum of BBOA-3 resembled that of LV-OOA and had negligible contributions from the HR-AMS BB tracer ions – C2H4O2+ (m∕z = 60.021) and C3H5O2+ (m∕z = 73.029); nevertheless, it was unambiguously related to wildfire emissions. This finding highlights the possibility that the influence of BB emission could be underestimated in regional air masses where highly oxidized BBOA (e.g., BBOA-3) might be a significant aerosol component but where primary BBOA tracers, such as levoglucosan, are depleted. We also examined OA chemical evolution for persistent BB plume events originating from a single fire source and found that longer solar radiation led to higher mass fraction of the chemically aged BBOA-2 and BBOA-3 and more oxidized aerosol. However, an analysis of the enhancement ratios of OA relative to CO (ΔOA ∕ΔCO) showed little difference between BB plumes transported primarily at night versus during the day, despite evidence of substantial chemical transformation in OA induced by photooxidation. These results indicate negligible net OA production in photochemically aged wildfire plumes observed in this study, for which a possible reason is that SOA formation was almost entirely balanced by BBOA volatilization. Nevertheless, the formation and chemical transformation of BBOA during atmospheric transport can significantly influence downwind sites with important implications for health and climate.

scholarly journals Review and uncertainty assessment of size-resolved scavenging coefficient formulations for snow scavenging of atmospheric aerosols

2013 ◽  
Vol 13 (6) ◽  
pp. 14823-14869 ◽  
Author(s):  
L. Zhang ◽  
X. Wang ◽  
M. D. Moran ◽  
J. Feng
Keyword(s):  
Atmospheric Aerosols ◽  
Atmospheric Aerosol ◽  
Collection Efficiency ◽  
Aerosol Particles ◽  
Field Measurements ◽  
Cross Sectional ◽  
Atmospheric Aerosol Particles ◽  
Order Of Magnitude ◽  
Snow Particle ◽  
Scavenging Coefficient

Abstract. Theoretical parameterizations for the size-resolved scavenging coefficient for atmospheric aerosol particles scavenged by snow (Λsnow) need assumptions regarding (i) snow particle–aerosol particle collection efficiency E, (ii) snow particle size distribution N(Dp), (iii) snow particle terminal velocity VD, and (iv) snow particle cross-sectional area A. Existing formulas for these parameters are reviewed in the present study and uncertainties in Λsnow caused by various combinations of these parameters are assessed. Different formulations of E can cause uncertainties in Λsnow of more than one order of magnitude for all aerosol sizes for typical snowfall intensities. E is the largest source of uncertainty among all the input parameters, similar to rain scavenging of atmospheric aerosols (Λrain) as was found in a previous study by Wang et al. (2010). However, other parameters can also cause significant uncertainties in Λsnow, and the uncertainties from these parameters are much larger than for Λrain. Specifically, different N(Dp) formulations can cause one-order-of-magnitude uncertainties in Λsnow for all aerosol sizes, as is also the case for a combination of uncertainties from both VD and A. In comparison, uncertainties in Λrain from N(Dp) are smaller than a factor of 5 and those from VD are smaller than a factor of 2. Λsnow estimated from one empirical formula generated from field measurements falls in the upper range of, or is slightly higher than, theoretically estimated values. The predicted aerosol concentrations obtained using different Λsnow formulas can differ by a factor of two for just a one-centimeter snowfall (liquid water equivalent of approximately 1 mm). It is likely that, for typical rain and snow event the removal of atmospheric aerosol particles by snow is more effective than removal by rain for equivalent precipitation amounts, although a firm conclusion requires much more evidence.

scholarly journals Optical properties of atmospheric aerosol over Cape Town, Western Cape of South Africa: Role of biomass burning

Atmósfera ◽  
2020 ◽  
Author(s):  
Abdulaziz Tunde Yakubu ◽  
Naven Chetty
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Atmospheric Aerosol ◽  
Cape Town ◽  
Optical Characteristics ◽  
Western Cape ◽  
Climate Trend ◽  
General Terms ◽  
Coarse Mode ◽  
The Impact

The optical characteristics of atmospheric aerosol are vital in the determination of the regional climate trend. Biomass burning is typically known to influence aerosol optical characteristics. Following the incessant biomass burning and the recent drop in precipitation over Western Cape, the aerosol optical properties with a focus on the impact of biomass burning are studied over Cape Town using data from AERONET (Aerosol Robotic Network) and MODIS (Moderate Resolution Imaging Spectroradiometer). In general terms, measurements from both platforms significantly agree on the estimates of aerosol optical depth (AOD) and water vapor content (WVC). The mean AOD 0.075 (± 0.022) and Ångström exponent (AE) 0.63 (± 0.19) derived from AERONET demonstrate the dominance of coarse mode aerosol typical of maritime aerosol. Similarly, aerosol particle size distributions display the predominance of coarse mode particles. However, the derived refractive index is more representative of urban-industrial aerosol. Also, estimated back-trajectories show that more than 70% of the aerosol particles over the region originate over the ocean. Atmospheric vapor increases from winter to summer and mainly influenced by air temperature, supersaturation level, and absorbing aerosol. Furthermore, two significant sources accounted for biomass burning related to high AOD values: local biomass burning and regionally transported aged smoke majorly from elsewhere in Sothern Africa.

scholarly journals Molecular markers of biomass burning and primary biological aerosols in urban Beijing: Size distribution and seasonal variation

2019 ◽  
Author(s):  
Shaofeng Xu ◽  
Lujie Ren ◽  
Yunchao Lang ◽  
Shengjie Hou ◽  
Hong Ren ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Climate Models ◽  
Aerosol Particles ◽  
Fine Fraction ◽  
Gas Chromatography Mass Spectrometry ◽  
Chemical Compositions ◽  
Urban Aerosols ◽  
Biological Aerosols ◽  
Haze Pollution

Abstract. Biomass burning and primary biological aerosol particles account for an important part of urban aerosols. Floods of studies have been conducted on the chemical compositions of fine aerosols (PM2.5) in megacities where the haze pollution is one of the severe environmental issues in China. However, little is known about their size distributions in atmospheric aerosols in the urban boundary layer. Here, size-segregated aerosol samples were collected in Beijing during haze and clear days from April 2017 to January 2018. Three anhydrosugars, six primary saccharides and four sugar alcohols in these samples were identified and quantified by gas chromatography/mass spectrometry (GC/MS). Higher concentrations of a biomass burning tracer, levoglucosan, were detected in autumn and winter than other seasons. Sucrose, glucose, fructose, mannitol and arabitol were more abundant in the bloom and glowing seasons. Particularly high level of trehalose was found in spring, which was largely associated with the Asian dust outflows. Anhydrosugars, xylose, maltose, inositol and erythritol are mainly existed in the fine mode ( 2.1 μm) between the haze and non-haze samples, while a size shift towards large particles and large GMDs in the fine fraction ( 5.8 μm. Our observations demonstrate that the sources, abundance, and chemical composition of urban aerosol particles are strongly size dependant in Beijing, which are important to better understand their environmental and health effects of urban aerosols and should be considered in air quality and climate models.

scholarly journals Regional Influence of Wildfires on Aerosol Chemistry in the Western US and Insights into Atmospheric Aging of Biomass Burning Organic Aerosol

2016 ◽  
Author(s):  
Shan Zhou ◽  
Sonya Collier ◽  
Daniel A. Jaffe ◽  
Nicole L. Briggs ◽  
Jonathan Hee ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Global Climate ◽  
Organic Aerosol ◽  
The United States ◽  
Global Scale ◽  
Aerosol Composition ◽  
Photo Oxidation ◽  
The Impact

Abstract. Biomass burning (BB) is one of the most important contributors to atmospheric aerosols on a global scale and wildfires are a large source of emissions that impact regional air quality and global climate. As part of the Biomass Burning Observation Project (BBOP) field campaign in summer 2013, we deployed a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS) coupled with a thermodenuder at the Mt. Bachelor Observatory (MBO, ~ 2.8 km above sea level) to characterize the impact of wildfire emissions on aerosol loading and properties in the Pacific Northwest region of the United States. MBO represents a remote background site in the western U.S. and it is frequently influenced by transported wildfire plumes during summer. Very clean conditions were observed at this site during periods without BB influence where the 5-min average (±1σ) concentration of non-refractory submicron aerosols (NR-PM1) was 3.7 ± 4.2 μg m−3. Aerosol concentration increased substantially (reaching up to 210 µg m−3 of NR-PM1) for periods impacted by transported BB plumes and aerosol composition was overwhelmingly organic. Based on Positive Matrix Factorization (PMF) of the HR-AMS data, three types of BB organic aerosol (BBOA) were identified, including a fresh, semivolatile BBOA-1 (O/C = 0.35; 20 % of OA mass) that correlated well with ammonium nitrate, an intermediately oxidized BBOA-2 (O/C = 0.60; 17 % of OA mass), and a highly oxidized BBOA-3 (O/C = 1.06; 31 % of OA mass) that showed very low volatility with only ~ 40 % mass loss at 200 °C. The remaining 32 % of the organic aerosol (OA) mass was attributed to a boundary layer (BL) OOA (BL-OOA; O/C = 0.69) representing OA influenced by BL dynamics and a low-volatility oxygenated OA (LV-OOA; O/C = 1.09) representing regional free troposphere aerosol. The mass spectrum of BBOA-3 resembled that of LV-OOA and had negligible contributions from the HR-AMS BB tracer ions – C2H4O2+ (m/z = 60.021) and C3H5O2+ (m/z = 73.029). This finding highlights the possibility that the influence of BB emission could be underestimated in regional air masses where highly oxidized BBOA (e.g. BBOA-3) might be a significant aerosol component. We also examined OA chemical evolution for persistent BB plume events originating from a single fire source and found that longer solar radiation led to higher mass fraction of the chemically aged BBOA-2 and BBOA-3 and more oxidized aerosol. However, an analysis of the enhancement ratios of OA relative to CO (ΔOA/ΔCO) showed little difference between BB plumes transported primarily at night versus during the day, despite evidence of substantial chemical transformation in OA induced by photo-oxidation. These results indicate negligible net OA production with photo-oxidation for wildfire plumes observed in this study, for which a possible reason is that SOA formation was almost entirely balanced by BBOA volatilization.

scholarly journals Review and uncertainty assessment of size-resolved scavenging coefficient formulations for below-cloud snow scavenging of atmospheric aerosols

2013 ◽  
Vol 13 (19) ◽  
pp. 10005-10025 ◽  
Author(s):  
L. Zhang ◽  
X. Wang ◽  
M. D. Moran ◽  
J. Feng
Keyword(s):  
Atmospheric Aerosols ◽  
Atmospheric Aerosol ◽  
Collection Efficiency ◽  
Aerosol Particles ◽  
Empirical Formulas ◽  
Cross Sectional ◽  
Atmospheric Aerosol Particles ◽  
Order Of Magnitude ◽  
Snow Particle ◽  
Scavenging Coefficient

Abstract. Theoretical parameterizations for the size-resolved scavenging coefficient for atmospheric aerosol particles scavenged by snow (Λsnow) need assumptions regarding (i) snow particle–aerosol particle collection efficiency E, (ii) snow-particle size distribution N(Dp), (iii) snow-particle terminal velocity VD, and (iv) snow-particle cross-sectional area A. Existing formulas for these parameters are reviewed in the present study, and uncertainties in Λsnow caused by various combinations of these parameters are assessed. Different formulations of E can cause uncertainties in Λsnow of more than one order of magnitude for all aerosol sizes for typical snowfall intensities. E is the largest source of uncertainty among all the input parameters, similar to rain scavenging of atmospheric aerosols (Λrain) as was found in a previous study by Wang et al. (2010). However, other parameters can also cause significant uncertainties in Λsnow, and the uncertainties from these parameters are much larger than for Λrain. Specifically, different N(Dp) formulations can cause one-order-of-magnitude uncertainties in Λsnow for all aerosol sizes, as is also the case for a combination of uncertainties from both VD and A. Assumptions about dominant snow-particle shape (and thus different VD and A) will cause an uncertainty of up to one order of magnitude in the calculated scavenging coefficient. In comparison, uncertainties in Λrain from N(Dp) are smaller than a factor of 5, and those from VD are smaller than a factor of 2. As expected, Λsnow estimated from empirical formulas generated from field measurements falls in the upper range of, or is higher than, the theoretically estimated values, which can be explained by additional processes/mechanisms that influence field-derived Λsnow but that are not considered in the theoretical Λsnow formulas. Predicted aerosol concentrations obtained by using upper range vs. lower range of Λsnow values (a difference of around two orders of magnitude in Λsnow) can differ by a factor of 2 for just a one-centimetre snowfall (liquid water equivalent of approximately 1 mm). Based on the median and upper range of theoretically generated Λsnow and Λsnow values, it is likely that, for typical rain and snow events, the removal of atmospheric aerosol particles by snow is more effective than removal by rain for equivalent precipitation amounts, although a firm conclusion requires much more evidence.

scholarly journals Sensitivity studies on the photolysis rates calculation in Amazonian atmospheric chemistry – Part I: The impact of the direct radiative effect of biomass burning aerosol particles

2005 ◽  
Vol 5 (5) ◽  
pp. 9325-9353 ◽  
Author(s):  
L. M. M. Albuquerque ◽  
K. M. Longo ◽  
S. R. Freitas ◽  
T. Tarasova ◽  
A. Plana Fattori ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Aerosol Particles ◽  
Atmospheric Modeling ◽  
Transfer Model ◽  
Radiative Effect ◽  
Tracer Transport ◽  
Visible Radiation ◽  
Photolysis Rates ◽  
The Impact

Abstract. The impact of the direct radiative effect of the aerosol particles on the calculation of the photolysis rates and consequently on the atmospheric chemistry in regional smoke clouds due to biomass burning over the Amazon basin is addressed in this work. It explores a case study for 19 September 2002 at LBA-RACCI-SMOCC (The Large-Scale Biosphere-Atmosphere experiment in Amazonia – Radiation, Cloud, and Climate Interactions – Smoke, Aerosols, Clouds, Rainfall and Climate) pasture site in SW Amazonia. The Tropospheric Ultraviolet Visible radiation model (TUV) version 4.2, (Madronich et al., 1987) is used for the photolysis rates calculation considering the layer aerosol optical depth from the Coupled Aerosol Tracer Transport model to the Brazilian Regional Atmospheric Modeling System (CATT-BRAMS) (Freitas et al., 2005). A dynamical aerosol model (Procópio et al., 2003) is included in the radiative transfer model to take into account the high temporal variability of the aerosol optical thickness. This methodology is tested by comparing modeled and measured clear sky solar irradiances. The results show a good agreement with measured PAR radiation values. The actinic flux attenuation, for AOT (500 nm) values around 1.94, decreases the photolysis rates by about 70% in the presence of near-ground smoke aerosol and above the smoke layer the photolysis process tends to increase by about 40%. A simulation of the ozone production is carried out using a one-dimensional photochemical box model and comparisons with observation are shown.

Sign in / Sign up

Export Citation Format

Share Document