Investigation of Aerosol Optical and Chemical Properties Using Humidity Controlled Cavity Ring-Down Spectroscopy
Investigation of Aerosol Optical and Chemical Properties Using Humidity Controlled Cavity Ring-Down Spectroscopy

Author:

Publisher:

Published: 2017

Total Pages: 113

ISBN-13:

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Scientists have been observing a change in the climate since the beginning of the 20th century that cannot be attributed to any of the natural influences of the past. Natural and anthropogenic substances and processes perturb the Earth's energy budget, contributing to climate change. In particular, aerosols (particles suspended in air) have long been recognized to be important in processes throughout the atmosphere that affect climate. They directly influence the radiative balance of the Earth's atmosphere, affect cloud formation and properties, and are also key air pollutants that contribute to a variety of respiratory and cardiovascular diseases. Despite their importance, aerosol particles are less well-characterized than greenhouse gases with respect to their sources, temporal and spatial concentration distribution, and physical and chemical properties. This uncertainty is mainly caused by the variable and insufficiently understood sources, formation and transformation processes, and complex composition of atmospheric particles. Instruments that can precisely and accurately measure and characterize the aerosol physical and chemical properties are in great demand. Atmospheric relative humidity (RH) has a crucial impact on the particles' optical properties; the RH dependence of the particle extinction coefficient is an important parameter for radiative forcing and thus climate change modeling. In this work a Humidity-Controlled Cavity Ring-Down (HC-CRD) aerosol optical instrument is described and its ability to measure RH dependent extinction coefficients and related hygroscopicity parameters is characterized.

Environmental Chamber Study of Atmospheric Chemistry and Secondary Organic Aerosol Formation Using Cavity Enhanced Absorption Spectroscopy
Environmental Chamber Study of Atmospheric Chemistry and Secondary Organic Aerosol Formation Using Cavity Enhanced Absorption Spectroscopy

Author: Yingdi Liu

Publisher:

Published: 2011

Total Pages: 76

ISBN-13: 9781124940335

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This thesis is only a part of my research work. For more information about my other work, including cavity ring down spectroscopy studies for peroxy radical, aerosol optical extinction, transparent thin and time of flight mass spectrometry studies for the initial steps of ozone and alkenes reaactions, please refer to my PhD thesis in Chemistry department, UC-Riverside.

Morphology Dependent Optical Properties of Mixed Organic/Inorganic Aerosol Particles
Morphology Dependent Optical Properties of Mixed Organic/Inorganic Aerosol Particles

Author: Kristin Di Monte

Publisher:

Published: 2022

Total Pages: 0

ISBN-13:

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Light extinction by atmospheric aerosol particles and their interactions with water are heavily dependent on their chemical composition, morphology, and mixing state. Both properties are crucial for determining the impact aerosol particles have on our climate. Since light extinction directly impacts visibility as well as climate, measurements of the extinction at varying relative humidities (RH) are needed in order to improve climate models. In this work we have measured the relative humidity dependence of aerosol light extinction and water uptake at 643 nm for particles of varying ammonium sulfate/organic compositions. Internal as well as external mixtures of levoglucosan, sucrose, and adipic acid with ammonium sulfate are investigated using cavity ring-down spectroscopy (CRDS). Optical growth factor (fRH) and hygroscopicity parameters ([kappa]) are reported for each aerosol system.

Light-Induced Processes in Optically-Tweezed Aerosol Droplets
Light-Induced Processes in Optically-Tweezed Aerosol Droplets

Author: Kerry J. Knox

Publisher: Springer Science & Business Media

Published: 2011-03-27

Total Pages: 209

ISBN-13: 3642163483

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Aerosols play a critical role in a broad range of scientific disciplines, such as atmospheric chemistry and physics, combustion science, drug delivery and human health. This thesis explores the fundamentals of a new technique for capturing single or multiple particles using light, and for characterising these particles by Raman or fluorescence spectroscopy. The outcome of this research represents a significant development in optical manipulation techniques, specifically in optical tweezing. These findings can be applied to studies of the mass accommodation of gas-phase water molecules adsorbing onto a water surface. Not only is this a fundamental process of interest to physical chemists, but it is important for understanding the role of aerosol particles in the atmosphere, including their ability to become cloud droplets. This new strategy for investigating aerosol dynamics is fundamental in helping us understand the indirect effect of aerosols on the climate.

Formation Mechanism and Control Strategies of Haze in China
Formation Mechanism and Control Strategies of Haze in China

Author: Hong He

Publisher: Springer Nature

Published: 2023-01-01

Total Pages: 263

ISBN-13: 9811969566

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This book summarizes the new major research findings about formation mechanism and control strategies of haze in China, including basic theories, key technologies, equipment and platforms and the applications and implementations of control technologies, in implementing the Strategic Priority Research Program (Class B) of Chinese Academy of Sciences. Different types of air pollution processes experienced by the developed countries in different stages are out-breaking simultaneously in China in the recent years and resulting a new type of “haze chemistry smog” pollution, which is different from the “London smog” and the “Los Angeles photochemical smog”. This book provides a useful reference for related researchers, engineers and policy-makers engaged in atmospheric pollution research, prevention and control in China and other countries.

Nucleation and Atmospheric Aerosols
Nucleation and Atmospheric Aerosols

Author: Colin D. O'Dowd

Publisher: Springer Science & Business Media

Published: 2007-11-15

Total Pages: 1275

ISBN-13: 1402064756

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Atmospheric particles are ubiquitous in the atmosphere: they form the seeds for cloud droplets and they form haze layers, blocking out incoming radiation and contributing to a partial cooling of our climate. They also contribute to poor air quality and health impacts. A large fraction of aerosols are formed from nucleation processes – that is a phase transition from vapour to liquid or solid particles. Examples are the formation of stable clusters about 1 nm in size from molecular collisions and these in turn can grow into larger (100 nm or more) haze particles via condensation to the formation of ice crystals in mixed phase or cold clouds. This book brings together the leading experts from the nucleation and atmospheric aerosols research communities to present the current state-of-the-art knowledge in these related fields. Topics covered are: Nucleation Experiment & Theory, Binary, Homogeneous and Heterogeneous Nucleation, Ion & Cluster Properties During Nucleation, Aerosol Characterisation & Properties, Aerosol Formation, Dynamics and Growth, Marine Aerosol Production, Aerosol-Cloud Interactions, Chemical Composition & Cloud Drop Activation, Remote Sensing of aerosol & clouds and Air Quality-Climate Interactions

Comparison of Near Surface and Column-Integrated Atmospheric Aerosol Optical Properties
Comparison of Near Surface and Column-Integrated Atmospheric Aerosol Optical Properties

Author: Rudra P Aryal

Publisher:

Published: 2012

Total Pages:

ISBN-13:

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Optical and chemical properties of size-resolved aerosols in near-surface air at Tudor Hill, Bermuda were measured between July 2006 and June 2009. Vertical distributions of aerosol backscattering and column-averaged aerosol optical properties were characterized with a Micro-pulse lidar (MPL) and a CIMEL automated sun-sky radiometer. The chemical species in size-segregated aerosols in marine air were compared with the surface level aerosol optical properties. The aerosol concentration, along with chemical components, was compared with the surface level wind speed and showed a significant correlation with the sea salt components. The non-sea salt components such as non-sea salt sulfate and ammonium did not show a correlation with the surface level wind speed. A comparison between scattering data at surface level with the extinction coefficient at the lowest altitude bin (75m) from the lidar inversion shows a consistent correlation but is quantitatively different. This quantitative discrepancy was explained based on the hygroscopic growth due to differences in relative humidity in measurement conditions. Aerosol optical properties measured near the surface were often significantly correlated with those averaged over the column. These include scattering by near-surface bulk aerosol at 530 nm versus column aerosol optical depth (AOD), near-surface sub-[mu]m scattering fraction versus column averaged sub-[mu]m scattering fraction, and the average angstrom exponent over column and lidar ratio derived using column integrated size distribution and complex refractive index. We also found that the single scattering albedo ([omega]o) measured at the surface by combining daily averages of the aerosol absorption and aerosol light scattering were in the same range as the instantaneous [omega]o retrieved for the column. The relative contribution of submicron aerosol light scattering to total aerosol light scattering is slightly higher in the column relative to the surface. Surface level wind speed was found to have a more important affect on bulk aerosol light scattering at the surface than in column.