Journal of Geophysical Research: Atmospheres, 2003
Petrochemical industrial facilities can emit large amounts of highly reactive hydrocarbons and NO... more Petrochemical industrial facilities can emit large amounts of highly reactive hydrocarbons and NOx to the atmosphere; in the summertime, such colocated emissions are shown to consistently result in rapid and efficient ozone (O3) formation downwind. Airborne measurements show initial hydrocarbon reactivity in petrochemical source plumes in the Houston, TX, metropolitan area is primarily due to routine emissions of the alkenes propene and ethene. Reported emissions of these highly reactive compounds are substantially lower than emissions inferred from measurements in the plumes from these sources. Net O3 formation rates and yields per NOx molecule oxidized in these petrochemical industrial source plumes are substantially higher than rates and yields observed in urban or rural power plant plumes. These observations suggest that reductions in reactive alkene emissions from petrochemical industrial sources are required to effectively address the most extreme O3 exceedences in the Houston...
... 2003 OSA/CLEO 2003 Page 3. ... REFERENCES 1. A. Fried, B. Henry, B. Wert, S. Sewell, and JR D... more ... 2003 OSA/CLEO 2003 Page 3. ... REFERENCES 1. A. Fried, B. Henry, B. Wert, S. Sewell, and JR Drummond, Laboratory, ground-based, and airborne tunable diode laser systems: Performance characteristics and applications in atmospheric studies, Appl. Phys. ...
As part of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites... more As part of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) 2008 field campaign, whole air samples were collected on board the NASA DC-8 airborne science platform, and analyzed for a suite of nonmethane hydrocarbons. During the springtime phase of the ARCTAS field campaign, halogen radical concentrations for Cl and Br were estimated during high latitude marine boundary layer ozone depletion events. Nonmethane hydrocarbons are removed from the atmosphere at different rates via photochemical oxidation by OH, Cl, and Br. Using selected hydrocarbons, the presence and abundance of halogen radicals can be determined based on their relative hydrocarbon reaction rates using the hydrocarbon clock method. Previous studies have found that surface layer ozone depletion events are typically associated with evidence of halogen chemistry, and the halogen radical estimates made during the ARCTAS campaign are comparable to measurements made during previ...
Atmospheric Chemistry and Physics Discussions, 2014
The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halo... more The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs) has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there have been indications of active iodine chemistry through observed enhancements in filterable iodide, probable detection of tropospheric IO, and recently, detection of atmospheric I<sub>2</sub>. Despite decades of research, significant uncertainty remains regarding the chemical mechanisms associated with the bromine-catalyzed depletion of ozone, as well as the complex interactions that occur in the polar boundary layer due to halogen chemistry. To investigate this, we developed a zero-dimensional photochemical model, con...
Lasers, Sources and Related Photonic Devices, 2010
ABSTRACT We will review the state of development and applications of difference-frequency generat... more ABSTRACT We will review the state of development and applications of difference-frequency generation based laser spectrometers to atmospheric research and discuss the operating conditions and techniques that enable high precision performance for ground and airborne environments.
Key gas-phase organic breakdown products like formaldehyde (HCHO) and acetaldehyde (CH3CHO) shoul... more Key gas-phase organic breakdown products like formaldehyde (HCHO) and acetaldehyde (CH3CHO) should behave similarly and predictably in continental outflow plumes. The INTEX-NA (ICARTT) and NARE-97 experiments provide a study set. We examine obervations and regional/global models describing the aldehyde species in low (0-4 km) continental outflow plumes. We find anomalies in their distributions, observed and modeled, which have improved our
A sensitive photoacoustic detection system for trace atmospheric measurements of HCl is described... more A sensitive photoacoustic detection system for trace atmospheric measurements of HCl is described. The results reported here suggest the capability of measuring HCl at the 50-parts-in-10(9) level with a prototype laboratory system. Further system improvements and atmospheric-measurement considerations are discussed.
The 2006 Intercontinental Chemical Transport Experiment Phase B (INTEX-B) Campaign was designed i... more The 2006 Intercontinental Chemical Transport Experiment Phase B (INTEX-B) Campaign was designed in part to quantify the outflow and evolution of gases and aerosols from aging plumes downwind of major tropical megacities such as Mexico City. Formaldehyde (CH2O), an important reactive gas phase intermediate, is photochemically produced as such plumes age and is involved in a number of important atmospheric processes, such as: hydrocarbon oxidation, ozone production, reactive hydrogen radical formation, and generation of carbon monoxide. This talk will present CH2O results acquired by a tunable diode laser absorption spectrometer operated onboard the NASA DC-8 aircraft during this campaign. Airborne CH2O distributions and measurement- model comparisons over a wide geographic region of this study, including Mexico, the Gulf of Mexico, and vast regions over the Pacific Ocean during the second campaign phase, will be presented. Comparisons and contrasts with results from other major metro...
ABSTRACT Tunable mid-infrared lager sources are the key to precision optical trace gas detection.... more ABSTRACT Tunable mid-infrared lager sources are the key to precision optical trace gas detection. Difference-frequency generation (DFG) based laser sources are among a few practical laser sources that have demonstrated ultra-high detection sensitivities during real-world applications when combined with appropriate signal enhancing and noise reduction spectroscopic techniques. This article will discuss the technical approaches, illustrate application examples of DFG sources, and offer perspectives to competing technologies. A He-Ne alignment lager visualizes a reentrant beam pattern of a 100 m, 182 pass astigmatic Herriott multi-pass absorption cell used in highly sensitive trace gas DFG spectrometers. [GRAPHICS] (C) 2009 by WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim
Journal of Geophysical Research: Atmospheres, 2003
Petrochemical industrial facilities can emit large amounts of highly reactive hydrocarbons and NO... more Petrochemical industrial facilities can emit large amounts of highly reactive hydrocarbons and NOx to the atmosphere; in the summertime, such colocated emissions are shown to consistently result in rapid and efficient ozone (O3) formation downwind. Airborne measurements show initial hydrocarbon reactivity in petrochemical source plumes in the Houston, TX, metropolitan area is primarily due to routine emissions of the alkenes propene and ethene. Reported emissions of these highly reactive compounds are substantially lower than emissions inferred from measurements in the plumes from these sources. Net O3 formation rates and yields per NOx molecule oxidized in these petrochemical industrial source plumes are substantially higher than rates and yields observed in urban or rural power plant plumes. These observations suggest that reductions in reactive alkene emissions from petrochemical industrial sources are required to effectively address the most extreme O3 exceedences in the Houston...
... 2003 OSA/CLEO 2003 Page 3. ... REFERENCES 1. A. Fried, B. Henry, B. Wert, S. Sewell, and JR D... more ... 2003 OSA/CLEO 2003 Page 3. ... REFERENCES 1. A. Fried, B. Henry, B. Wert, S. Sewell, and JR Drummond, Laboratory, ground-based, and airborne tunable diode laser systems: Performance characteristics and applications in atmospheric studies, Appl. Phys. ...
As part of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites... more As part of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) 2008 field campaign, whole air samples were collected on board the NASA DC-8 airborne science platform, and analyzed for a suite of nonmethane hydrocarbons. During the springtime phase of the ARCTAS field campaign, halogen radical concentrations for Cl and Br were estimated during high latitude marine boundary layer ozone depletion events. Nonmethane hydrocarbons are removed from the atmosphere at different rates via photochemical oxidation by OH, Cl, and Br. Using selected hydrocarbons, the presence and abundance of halogen radicals can be determined based on their relative hydrocarbon reaction rates using the hydrocarbon clock method. Previous studies have found that surface layer ozone depletion events are typically associated with evidence of halogen chemistry, and the halogen radical estimates made during the ARCTAS campaign are comparable to measurements made during previ...
Atmospheric Chemistry and Physics Discussions, 2014
The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halo... more The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs) has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there have been indications of active iodine chemistry through observed enhancements in filterable iodide, probable detection of tropospheric IO, and recently, detection of atmospheric I<sub>2</sub>. Despite decades of research, significant uncertainty remains regarding the chemical mechanisms associated with the bromine-catalyzed depletion of ozone, as well as the complex interactions that occur in the polar boundary layer due to halogen chemistry. To investigate this, we developed a zero-dimensional photochemical model, con...
Lasers, Sources and Related Photonic Devices, 2010
ABSTRACT We will review the state of development and applications of difference-frequency generat... more ABSTRACT We will review the state of development and applications of difference-frequency generation based laser spectrometers to atmospheric research and discuss the operating conditions and techniques that enable high precision performance for ground and airborne environments.
Key gas-phase organic breakdown products like formaldehyde (HCHO) and acetaldehyde (CH3CHO) shoul... more Key gas-phase organic breakdown products like formaldehyde (HCHO) and acetaldehyde (CH3CHO) should behave similarly and predictably in continental outflow plumes. The INTEX-NA (ICARTT) and NARE-97 experiments provide a study set. We examine obervations and regional/global models describing the aldehyde species in low (0-4 km) continental outflow plumes. We find anomalies in their distributions, observed and modeled, which have improved our
A sensitive photoacoustic detection system for trace atmospheric measurements of HCl is described... more A sensitive photoacoustic detection system for trace atmospheric measurements of HCl is described. The results reported here suggest the capability of measuring HCl at the 50-parts-in-10(9) level with a prototype laboratory system. Further system improvements and atmospheric-measurement considerations are discussed.
The 2006 Intercontinental Chemical Transport Experiment Phase B (INTEX-B) Campaign was designed i... more The 2006 Intercontinental Chemical Transport Experiment Phase B (INTEX-B) Campaign was designed in part to quantify the outflow and evolution of gases and aerosols from aging plumes downwind of major tropical megacities such as Mexico City. Formaldehyde (CH2O), an important reactive gas phase intermediate, is photochemically produced as such plumes age and is involved in a number of important atmospheric processes, such as: hydrocarbon oxidation, ozone production, reactive hydrogen radical formation, and generation of carbon monoxide. This talk will present CH2O results acquired by a tunable diode laser absorption spectrometer operated onboard the NASA DC-8 aircraft during this campaign. Airborne CH2O distributions and measurement- model comparisons over a wide geographic region of this study, including Mexico, the Gulf of Mexico, and vast regions over the Pacific Ocean during the second campaign phase, will be presented. Comparisons and contrasts with results from other major metro...
ABSTRACT Tunable mid-infrared lager sources are the key to precision optical trace gas detection.... more ABSTRACT Tunable mid-infrared lager sources are the key to precision optical trace gas detection. Difference-frequency generation (DFG) based laser sources are among a few practical laser sources that have demonstrated ultra-high detection sensitivities during real-world applications when combined with appropriate signal enhancing and noise reduction spectroscopic techniques. This article will discuss the technical approaches, illustrate application examples of DFG sources, and offer perspectives to competing technologies. A He-Ne alignment lager visualizes a reentrant beam pattern of a 100 m, 182 pass astigmatic Herriott multi-pass absorption cell used in highly sensitive trace gas DFG spectrometers. [GRAPHICS] (C) 2009 by WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim
Uploads
Papers by A. Fried