Download or read book Quantitative Detection of Trace Gas Species in the Atmosphere Using LED Broadband Cavity Enhanced Absorption Spectroscopy written by Anna Marie Hollingsworth and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A broadband version of cavity enhanced absorption spectroscopy (BBCEAS) has been applied to measure the ambient concentrations of reactive trace gases, particularly nitrogen dioxide (NO2) in the polluted urban environment and molecular iodine (I2) in the marine boundary layer. The spectrometer's light source, a light emitting diode (LED), enables absorption spectra of gas samples to be acquired over 50 nm bandwidths at visible and nearultraviolet wavelengths. Differential optical absorption spectroscopy (DOAS) is then applied to unambiguously identify and quantify the various absorbers present in the samples. Especially difficult operating conditions were encountered during the instrument's first field deployment onboard the research vessel RRS Discovery. As a result, the instrument did not achieve the I2 detection limits it had demonstrated in laboratory testing and was unable to detect any I2 signal in the mid-Atlantic Ocean during the Reactive Halogens in the Marine Boundary Layer Experiment. However, iodine was detected around many night-time low tides during the BIOFLUX II campaign at the Mace Head Atmospheric Research Station in County Galway, Ireland. The maximum I2 concentration of 608 pptv (parts per trillion by volume) correlated with the campaign's lowest tide, and is three times greater than any previous report of atmospheric I2 concentrations. The BIOFLUX observations support current understanding that coastal I2 derives from seaweed (particularly kelp species) exposed to air around low tide. LED-BBCEAS measurements of NO2 made on the University campus during the Leicester Air Quality Measurement Project are compared with data from two chemiluminescence instruments. The need to closely co-locate instruments during comparisons of the various techniques is discussed, and evidence of a possible interference in the chemiluminescence measurements has been found.
Download or read book Trace Detection of Atmospheric Gases Using Cavity Enhanced Spectroscopy written by and published by . This book was released on 2004 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Spectroscopic Monitoring of the Atmosphere written by Weidong Chen and published by Elsevier. This book was released on 2021-06-09 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Spectroscopic Monitoring of the Atmosphere provides a comprehensive overview of cutting-edge technologies and monitoring applications. Concepts are illustrated by numerous examples with information on spectroscopic techniques and applications widely distributed throughout the text. This information is important for researchers to gain an overview of recent developments in the field and make informed selections among the most suitable techniques. This volume also provides information that will allow researchers to explore implementing and developing new diagnostic tools or new approaches for trace gas and aerosol sensing themselves. Advances in Spectroscopic Monitoring of the Atmosphere covers advanced and newly emerging spectroscopic techniques for optical metrology of gases and particles in the atmosphere. This book will be a valuable reference for atmospheric scientists, including those whose focus is applying the methods to atmospheric studies, and those who develop instrumentation. It will also serve as a useful introduction to researchers entering the field and provide relevant examples to researchers and students developing and applying optical sensors for a variety of other scientific, technical, and industrial uses. - Overview of new applications including remote sensing by UAV, laser heterodyne radiometry, dual comb spectroscopy, and more - Features in-situ observations and measurements for real-world data - Includes content on leading edge optical sensors
Download or read book Biogenic Trace Gases written by P. A. Matson and published by John Wiley & Sons. This book was released on 2009-05-27 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace gases are those that are present in the atmosphere at relatively low concentrations. Small changes in their concentrations can have profound implications for major atmospheric fluxes, and thereore, can be used as indicators in studies of global change, global biogeochemical cycling and global warming. This new how-to guide will detail the concepts and techniques involved in the detection and measurement of trace gases, and the impact they have on ecological studies. Introductory chapters look at the role of trace gases in global cycles, while later chapters go on to consider techniques for the measurement of gases in various environments and at a range of scales. A how-to guide for measuring atmospheric trace gases. Techniques described are of value in addressing current concerns over global climate change.
Download or read book Development and Deployment of a Broadband Cavity Enhanced Absorption Spectroscopy Instrument for Airborne Measurements of Trace Gases written by Oliver John Kennedy and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Time resolved Broadband Cavity enhanced Absorption Spectroscopy for Chemical Kinetics written by and published by . This book was released on 2013 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental measurements of elementary reaction rate coefficients and product branching ratios are essential to our understanding of many fundamentally important processes in Combustion Chemistry. However, such measurements are often impossible because of a lack of adequate detection techniques. Some of the largest gaps in our knowledge concern some of the most important radical species, because their short lifetimes and low steady-state concentrations make them particularly difficult to detect. To address this challenge, we propose a novel general detection method for gas-phase chemical kinetics: time-resolved broadband cavity-enhanced absorption spectroscopy (TR-BB-CEAS). This all-optical, non-intrusive, multiplexed method enables sensitive direct probing of transient reaction intermediates in a simple, inexpensive, and robust experimental package.
Download or read book Differential Optical Absorption Spectroscopy of Trace Gas Species and Aerosols in the Upper Ohio River Valley written by Christopher Paul Beekman and published by . This book was released on 2010 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this research, it is hypothesized that recently developed theoretical considerations of atmospheric radiative transfer in horizontally in-homogeneous atmospheres can be applied to the remote measurement of anthropogenic plumes. To this end, a MAX-DOAS spectrometer, designed around a BandW-TEK BTU142 spectrometer was constructed and characterized. It was found that the MAX-DOAS spectrometer has a measured resolution of 0.282 nm, and a noise level of 178 counts at 75% pixel saturation, sufficient to resolve accurately the absorptions of important atmospheric species, including SO2, NO2, HCHO, and O4. The theory of MAX-DOAS spectral analysis was examined in detail, in particular the processing of reference absorption cross-section spectra for use in regression analyses of scattered solar radiation. For the purposes of inversion, optimal estimation software was designed and investigated for suitability in retrieving vertical profiles of atmospheric species. This software is shown to perform well under conditions of both typical and non-typical noise levels using synthetic spectral data and known profiles of three atmospheric species. Furthermore, an extensive examination of the residuals of DOAS spectral analysis was performed, to validate the assumption of normally distributed errors in the inversion process. Investigated methodologies were applied to spectral data collected over nine days in 2008 in the Upper Ohio River Valley. Aerosol extinction coefficient profiles were successfully retrieved, with an average peak value of 0.549 km−1. For the same measurement period, in-plume measurements of SO2 and NO2 concentration from a coal-fired power plant were conducted using recently developed methodologies to account for in-plume solar radiative transfer effects.
Download or read book Fast response measurements of organic trace species in the Earth s atmosphere written by Geiger, Felix and published by KIT Scientific Publishing. This book was released on 2015-05-04 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work describes the development of an ultra-light-weight Proton-Transfer-Reaction Mass Spectrometer (PTR-MS), its detailed qualification, ground-based and airborne applications and studies on VOC emissions in connection with fossil fuel production. The new system was used aboard a mobile laboratory in order to investigate the chemical fingerprints of the diverse emitters at oil and natural gas well pads. Emissions of aromatic hydrocarbons at a hydraulically fractured well have been studied.
Download or read book Broadband Cavity Enhanced Absorption Spectroscopy written by Paul Samuel Johnston and published by . This book was released on 2009 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atmospheric Measurements of Biogenic and Anthropogenic Emissions by Broadband Cavity Enhanced Absorption Spectroscopy written by Thomas John Adams and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book First Trace Gas Measurements Using Fourier Transform Infrared Solar Absorption Spectroscopy at the University of Toronto Atmospheric Observatory written by Aldona Wiacek and published by . This book was released on 2006 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: A systematic study showed that the effect of several different layering schemes (implicit retrieval constraints) on the retrieved vertical profile is less than 5% for N2O and HF, and less than 2% for NO, NO 2, CH4 and HCl; however, retrieved profiles of H2O showed differences up to 13% when the layering scheme was varied. A maximum tropospheric layer thickness of 0.8 km is inferred for accurate H2O retrievals. A new high-resolution (0.004 cm-1) research-grade Fourier transform spectrometer was installed at the University of Toronto Atmospheric Observatory (TAO), and commissioned in October 2001. TAO fills a coverage gap in North America in the Network for the Detection of Atmospheric Composition Change (NDACC), and was accepted as a Complementary Station in March 2004 as a direct result of work presented in this thesis. Finally, the usefulness of Fourier Transform InfraRed (FTIR) observations for studying different regions of the atmosphere was demonstrated by (1) documenting a limited sensitivity of ground-based measurements to mesospheric-lower thermospheric concentrations of NO, (2) correlating anomalously high stratospheric HCl, HF and O3 concentrations derived at TAO with the passage of a polar air filament above Toronto, and (3) showing very good agreement between monthly mean abundances of tropospheric CO between January 2002--September 2003 and spatially coincident MOPITT satellite measurements. Trace gas concentrations are derived using an existing Optimal Estimation Method (OEM) retrieval algorithm implemented at TAO as part of this work. A set of prior constraints necessary for retrievals of vertical profiles of trace gases using the OEM approach was optimized, and includes a priori volume mixing ratio profiles suited to TAO's location, and the prior and measurement noise covariances. A three-year time series of O3, NO. NO2, HCl, HF, N2O and CH4 (exhibiting the known seasonal cycles) was submitted to the NDACC database for long-terra monitoring, trend detection, and satellite validation purposes. A quantitative retrieval characterization was performed whereby the averaging kernels, weighting functions, measurement, smoothing and temperature error covariances of the retrievals of these seven gases were calculated. The degrees of freedom for signal ranged from 1.10 for NO2 to 4.12 for N2O.
Download or read book Sensitive Absorption Spectroscopy Techniques for Quantitative Detection of Species in Flames and Ambient Air written by Scott M. Spuler and published by . This book was released on 2001 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements of Atmospheric Trace Gases by Multi axis and Direct Sun Differential Optical Absorption Spectroscopy and Validation of the Ozone Monitoring Instrument Satellite Trace Gas Data written by Elena Spinei and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of Atmospheric Trace Gases by Absorption Spectroscopy written by Simon Richard Aliwell and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cavity enhanced Spectroscopies for Applications of Remote Sensing Chemical Kinetics and Detection of Radical Species written by Thinh Quoc Bui and published by . This book was released on 2015 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes applications of cavity enhanced spectroscopy towards applications of remote sensing, chemical kinetics and detection of transient radical molecular species. Both direct absorption spectroscopy and cavity ring-down spectroscopy are used in this work. Frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) was utilized for measurements of spectral lineshapes of O2 and CO2 for obtaining laboratory reference data in support of NASA's OCO-2 mission. FS-CRDS is highly sensitive (>10 km absorption path length) and precise (>10000:1 SNR), making it ideal to study subtle non-Voigt lineshape effects. In addition, these advantages of FS-CRDS were further extended for measuring kinetic isotope effects: A dual-wavelength variation of FS-CRDS was used for measuring precise D/H and 13C/12C methane isotope ratios (sigma>0.026%) for the purpose of measuring the temperature dependent kinetic isotope effects of methane oxidation with O(1D) and OH radicals. Finally, direct absorption spectroscopic detection of the trans-DOCO radical via a frequency combs spectrometer was conducted in collaboration with professor Jun Ye at JILA/University of Colorado.
Download or read book Tunable Diode Laser Absorption Spectroscopy for Trace Gas Measurements with High Sensitivity and Low Drift written by Christoph Dyroff and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the mechanical and opto-electronic design of laser spectrometers for measuring two very important atmospheric gases, namely water vapor and its isotopic ratios, and formaldehyde. For measuring water vapor, shot-noise limited sensitivity has been achieved by a careful choice of system components and data processing. For measuring formaldehyde, a selective sample modulation exploiting the Stark effect has been used to greatly improve the sensitivity.
Download or read book Development and Atmospheric Applications of a Novel Broadband Cavity Enhanced Absorption Spectrometer written by Justin Mohsen Langridge and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
