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• 28721. [Image] Dispersed winter recreation use patterns and visitor attitudes at Crater Lake - Diamond Lake, Oregon

  	ill., forms; Thesis (M.S.)--Oregon State University;
  	Citation × Citation Citation Abstract Copy Title: Dispersed winter recreation use patterns and visitor attitudes at Crater Lake - Diamond Lake, Oregon Author: Thompson, Terry Jo Year: 1976, 2009, 2010 ill., forms; Thesis (M.S.)--Oregon State University; Title: Dispersed winter recreation use patterns and visitor attitudes at Crater Lake - Diamond Lake, Oregon Author: Thompson, Terry Jo Year: 1976, 2009, 2010 ill., forms; Thesis (M.S.)--Oregon State University; Close

• 28722. [Image] Crater Lake National Park oral history series, John Salinas

  	photo; "Interviewed by Stephen R. Mark on April 7, 1998; transcribed by Renee Edwards, September 1998." - T.p.;
  	Citation × Citation Citation Abstract Copy Title: Crater Lake National Park oral history series, John Salinas Author: Mark, Stephen R. Year: 1998, 2009, 2010 photo; "Interviewed by Stephen R. Mark on April 7, 1998; transcribed by Renee Edwards, September 1998." - T.p.; Title: Crater Lake National Park oral history series, John Salinas Author: Mark, Stephen R. Year: 1998, 2009, 2010 photo; "Interviewed by Stephen R. Mark on April 7, 1998; transcribed by Renee Edwards, September 1998." - T.p.; Close

• 28723. [Image] Crater Lake National Park oral history series, Larry Smith

  	photo; "Interviewed by Stephen R. Mark on February 10, 1989; Transcribed by Chris Prout, August 1997." - T.p.;
  	Citation × Citation Citation Abstract Copy Title: Crater Lake National Park oral history series, Larry Smith Author: Mark, Stephen R. Year: 1989, 2009, 2010 photo; "Interviewed by Stephen R. Mark on February 10, 1989; Transcribed by Chris Prout, August 1997." - T.p.; Title: Crater Lake National Park oral history series, Larry Smith Author: Mark, Stephen R. Year: 1989, 2009, 2010 photo; "Interviewed by Stephen R. Mark on February 10, 1989; Transcribed by Chris Prout, August 1997." - T.p.; Close

• 28724. [Image] Program development and design criteria for activity center/hotel facility at Rim Village: Crater lake National Park, Crater Lake, Oregon [volume 1]

  	2 v.: ill., maps, photos (some color); "Volume One: Program" and "Volume Two: Reference." Both volumes: "Prepared for the National Park Service, Denver Service Center." - Cover/Title pages; Volume Two ...
  	Citation × Citation Citation Abstract Copy Title: Program development and design criteria for activity center/hotel facility at Rim Village: Crater lake National Park, Crater Lake, Oregon [volume 1] Author: Project Team Year: 1989, 2009, 2010 2 v.: ill., maps, photos (some color); "Volume One: Program" and "Volume Two: Reference." Both volumes: "Prepared for the National Park Service, Denver Service Center." - Cover/Title pages; Volume Two includes "Wind tunnel study of snow conditions at Rim Village Crater Lake National Park," CPP Project 86-0361, prepared October 1987; Project Team consists of various architects and mechanical, structural, wind and civil engineering representatives and a snow consultant. Title: Program development and design criteria for activity center/hotel facility at Rim Village: Crater lake National Park, Crater Lake, Oregon [volume 1] Author: Project Team Year: 1989, 2009, 2010 2 v.: ill., maps, photos (some color); "Volume One: Program" and "Volume Two: Reference." Both volumes: "Prepared for the National Park Service, Denver Service Center." - Cover/Title pages; Volume Two includes "Wind tunnel study of snow conditions at Rim Village Crater Lake National Park," CPP Project 86-0361, prepared October 1987; Project Team consists of various architects and mechanical, structural, wind and civil engineering representatives and a snow consultant. Close

• 28725. [Image] Crater Lake National Park oral history series, Carrol B. Howe

  	photo ; "Interviewed by Stephen R. Mark on January 23, 1992; Transcribed by Chris Prout, July 1997." - T.p.
  	Citation × Citation Citation Abstract Copy Title: Crater Lake National Park oral history series, Carrol B. Howe Author: Mark, Stephen R. Year: 1992, 2010 photo ; "Interviewed by Stephen R. Mark on January 23, 1992; Transcribed by Chris Prout, July 1997." - T.p. Title: Crater Lake National Park oral history series, Carrol B. Howe Author: Mark, Stephen R. Year: 1992, 2010 photo ; "Interviewed by Stephen R. Mark on January 23, 1992; Transcribed by Chris Prout, July 1997." - T.p. Close

• 28726. [Article] Oregon South Coast Estuaries: Hunter Creek, Pistol River, Chetco River, & Winchuck River Tidal Wetlands Assessment (2012-2015)

  Abstract -- Although tidal wetlands on the Oregon South Coast are limited in extent, they may be particularly valuable for a variety of wetland functions. This assessment combines the Brophy (2007) and ...

  Citation × Citation Citation Abstract Copy Title: Oregon South Coast Estuaries: Hunter Creek, Pistol River, Chetco River, & Winchuck River Tidal Wetlands Assessment (2012-2015) Abstract -- Although tidal wetlands on the Oregon South Coast are limited in extent, they may be particularly valuable for a variety of wetland functions. This assessment combines the Brophy (2007) and Adamus (2005) approaches to quantify the extent and causes of habitat loss and hydrogeomorphic changes in tidal wetlands of four Oregon South Coast Estuaries. The potential for restoring critical habitat and wetland functions is ranked using Ecological Prioritization Criteria (Brophy, 2007), while indicators of function, risk, and integrity are evaluated using scoring models from the Adamus (2005) Hydrogeomorphic (HGM) Rapid Assessment Method. The extent of inundation (head of tide) during King Tide conditions was observed and documented by staff and volunteers. Field measurements of salinity concentrations and stratification during high and low flow were tabulated. The historic aerial photo record was examined to detect channel migration, floodplain re-vegetation, and human-caused alterations. Related studies were combined with these observations to provide a summary of estuary hydrology, sedimentation, and channel stability related to wetland establishment and loss in each of the four estuaries. Ecological priority scores (Brophy, 2007) varied with wetland size, tidal channel condition, connectivity, and diversity of vegetation classes. Wetlands were categorized as restoration or conservation types, and priority ranks for wetlands were depicted on orthophoto base maps. Tidal wetlands and nearby floodplain wetlands in a variety of geomorphic settings were surveyed using the HGM protocol, including one “reference” and one restoration site . The HGM survey scores 55 indicators, including botanical transects, used to rank wetland functions (calculated by indicator scoring models). Risks to wetlands include human disturbances in close proximity to the wetlands and floodplains, resulting from the narrow valley floors in this tectonically active region. Wetland integrity is threatened by a surprising large proportion of non-native species in the botanical transects, 40%. Wetland indicators that scored low, and could be restored or enhanced, are discussed in a restoration considerations narrative. Wetland descriptions include lists of plant species, grouped by wetland status, native/non-native, and perennial/annual persistence. In addition to the HGM scores, an analysis of cover and diversity of all plant species in plots, off-transect species diversity, and waterfowl food distribution was completed using a wetland vegetation database developed for the Oregon South Coast. Title: Oregon South Coast Estuaries: Hunter Creek, Pistol River, Chetco River, & Winchuck River Tidal Wetlands Assessment (2012-2015) Abstract -- Although tidal wetlands on the Oregon South Coast are limited in extent, they may be particularly valuable for a variety of wetland functions. This assessment combines the Brophy (2007) and Adamus (2005) approaches to quantify the extent and causes of habitat loss and hydrogeomorphic changes in tidal wetlands of four Oregon South Coast Estuaries. The potential for restoring critical habitat and wetland functions is ranked using Ecological Prioritization Criteria (Brophy, 2007), while indicators of function, risk, and integrity are evaluated using scoring models from the Adamus (2005) Hydrogeomorphic (HGM) Rapid Assessment Method. The extent of inundation (head of tide) during King Tide conditions was observed and documented by staff and volunteers. Field measurements of salinity concentrations and stratification during high and low flow were tabulated. The historic aerial photo record was examined to detect channel migration, floodplain re-vegetation, and human-caused alterations. Related studies were combined with these observations to provide a summary of estuary hydrology, sedimentation, and channel stability related to wetland establishment and loss in each of the four estuaries. Ecological priority scores (Brophy, 2007) varied with wetland size, tidal channel condition, connectivity, and diversity of vegetation classes. Wetlands were categorized as restoration or conservation types, and priority ranks for wetlands were depicted on orthophoto base maps. Tidal wetlands and nearby floodplain wetlands in a variety of geomorphic settings were surveyed using the HGM protocol, including one “reference” and one restoration site . The HGM survey scores 55 indicators, including botanical transects, used to rank wetland functions (calculated by indicator scoring models). Risks to wetlands include human disturbances in close proximity to the wetlands and floodplains, resulting from the narrow valley floors in this tectonically active region. Wetland integrity is threatened by a surprising large proportion of non-native species in the botanical transects, 40%. Wetland indicators that scored low, and could be restored or enhanced, are discussed in a restoration considerations narrative. Wetland descriptions include lists of plant species, grouped by wetland status, native/non-native, and perennial/annual persistence. In addition to the HGM scores, an analysis of cover and diversity of all plant species in plots, off-transect species diversity, and waterfowl food distribution was completed using a wetland vegetation database developed for the Oregon South Coast. Close

• 28727. [Article] Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching

  The Meers Fault (Oklahoma) is one of few seismogenic structures with Holocene surface expression in the stable continental region of North America. Only the ~37 km-long southeastern section of the ~55 ...

  Citation × Citation Citation Abstract Copy Title: Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching Author: Hornsby, Kristofer Tyler Year: 2017 The Meers Fault (Oklahoma) is one of few seismogenic structures with Holocene surface expression in the stable continental region of North America. Only the ~37 km-long southeastern section of the ~55 km long Meers Fault is interpreted to be Holocene-active. The ~17 km-long northwestern section is considered to be Quaternary-active (pre-Holocene); however, its low-relief geomorphic expression and anthropogenic alteration have presented difficulties in evaluating the fault length and style of Holocene deformation. We reevaluate surface expression and earthquake timing of the northwestern portion of the Meers Fault to improve fault characterization, earthquake rupture models, and seismic hazard evaluations based on fault length. We use a combination of airborne lidar (0.5--2 m-resolution), historical aerial photos, and new balloon-based photogrammetric (Structure from Motion) topography (0.25--0.5 m-resolution) collected in this study to analyze and characterize the fault scarp and local fault zone geomorphology. In the northwest, complex surface deformation includes fault splays, a left step, subtle monoclinal warping, and a minor change in fault strike The fault is evident in the landscape as linear escarpments, incised channels on the up-thrown side of the scarp, and closed depressions on the downthrown side. I use topographic profiles, measured perpendicular to the fault scarp to show that the northwest scarp is characterized by decimeter surface offsets. Where the fault traverses the Post Oak Conglomerate the fault zone width rarely exceeds 25 m, in the Hennessey Shale I document an increase in fault zone width with deformation occurring over 20 m to 115 m. I further examined the northwest section of the fault in a paleoseismic excavation where weathered Permian Hennessey Shale and a ~1--2 m-thick veneer of Holocene alluvial deposits have been folded and warped during three surface-folding earthquakes. In an adjacent stream exposure these units are also faulted near the ground surface. Paleoearthquake age modeling (Oxcal) constrained by accelerated mass spectrometry (AMS) dating of detrital charcoal and optically stimulated luminescence (OSL) dating of sandy alluvial beds indicates two earthquakes occurred since ~6152-5550 cal. years BP and one possibly older event along the erosional unconformity along the Hennessey Shale bedrock. This analysis lengthens the Holocene extent of the Meers Fault by ~6 km, to ~43 km, and extends the paleoseismic record of the Meers Fault to ~9598 cal. years BP. These data will improve fault-rupture and earthquake recurrence models used for seismic hazard analysis of the Meers Fault. Title: Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching Author: Hornsby, Kristofer Tyler Year: 2017 The Meers Fault (Oklahoma) is one of few seismogenic structures with Holocene surface expression in the stable continental region of North America. Only the ~37 km-long southeastern section of the ~55 km long Meers Fault is interpreted to be Holocene-active. The ~17 km-long northwestern section is considered to be Quaternary-active (pre-Holocene); however, its low-relief geomorphic expression and anthropogenic alteration have presented difficulties in evaluating the fault length and style of Holocene deformation. We reevaluate surface expression and earthquake timing of the northwestern portion of the Meers Fault to improve fault characterization, earthquake rupture models, and seismic hazard evaluations based on fault length. We use a combination of airborne lidar (0.5--2 m-resolution), historical aerial photos, and new balloon-based photogrammetric (Structure from Motion) topography (0.25--0.5 m-resolution) collected in this study to analyze and characterize the fault scarp and local fault zone geomorphology. In the northwest, complex surface deformation includes fault splays, a left step, subtle monoclinal warping, and a minor change in fault strike The fault is evident in the landscape as linear escarpments, incised channels on the up-thrown side of the scarp, and closed depressions on the downthrown side. I use topographic profiles, measured perpendicular to the fault scarp to show that the northwest scarp is characterized by decimeter surface offsets. Where the fault traverses the Post Oak Conglomerate the fault zone width rarely exceeds 25 m, in the Hennessey Shale I document an increase in fault zone width with deformation occurring over 20 m to 115 m. I further examined the northwest section of the fault in a paleoseismic excavation where weathered Permian Hennessey Shale and a ~1--2 m-thick veneer of Holocene alluvial deposits have been folded and warped during three surface-folding earthquakes. In an adjacent stream exposure these units are also faulted near the ground surface. Paleoearthquake age modeling (Oxcal) constrained by accelerated mass spectrometry (AMS) dating of detrital charcoal and optically stimulated luminescence (OSL) dating of sandy alluvial beds indicates two earthquakes occurred since ~6152-5550 cal. years BP and one possibly older event along the erosional unconformity along the Hennessey Shale bedrock. This analysis lengthens the Holocene extent of the Meers Fault by ~6 km, to ~43 km, and extends the paleoseismic record of the Meers Fault to ~9598 cal. years BP. These data will improve fault-rupture and earthquake recurrence models used for seismic hazard analysis of the Meers Fault. Close

• 28728. [Article] Analyzing Experimental Data and Model Parameters: Implications for Predictions of SOA Using Chemical Transport Models

  Despite critical importance for air quality and climate predictions, accurate representation of secondary organic aerosol (SOA) formation remains elusive. An essential addition to the ongoing discussion ...

  Citation × Citation Citation Abstract Copy Title: Analyzing Experimental Data and Model Parameters: Implications for Predictions of SOA Using Chemical Transport Models Author: Barsanti, Kelley, Carlton, Annmarie G., Chung, Serena H. Year: 2013 Despite critical importance for air quality and climate predictions, accurate representation of secondary organic aerosol (SOA) formation remains elusive. An essential addition to the ongoing discussion of improving model predictions is an acknowledgement of the linkages between experimental conditions, parameter optimization and model output, as well as the linkage between empirically-derived partitioning parameters and the physicochemical properties of SOA they represent in models. In this work, a "best available" set of SOA modeling parameters is selected by comparing predicted SOA yields and mass concentrations with observed yields and mass concentrations from a comprehensive list of published smog chamber studies. Evaluated SOA model parameters include existing parameters for two product (2p) and volatility basis set (VBS) modeling frameworks, and new 2p-VBS parameters; 2p-VBS parameters are developed to exploit advantages of the VBS approach within the computationally-economical and widely-used 2p framework. Fine particulate matter (PM2.5) and SOA mass concentrations are simulated for the continental United States using CMAQv.4.7.1; results are compared for a base case (with default CMAQ parameters) and two best available parameter cases to illustrate the high- and low-NOx limits of biogenic SOA formation from monoterpenes. Results are discussed in terms of implications for current chemical transport model simulations and recommendations are provided for future modeling and measurement efforts. The comparisons of SOA yield predictions with data from 22 published chamber studies illustrate that: (1) SOA yields for naphthalene, and cyclic and > C5 straight-chain/branched alkanes are not well represented using either the newly developed or existing parameters for low-yield aromatics and lumped alkanes, respectively; and (2) for four of seven volatile organic compound+oxidant systems, the 2p-VBS parameters better represent chamber data than do the default CMAQ v.4.7.1 parameters. Using the "best available" parameters (combination of published 2p and newly derived 2p-VBS), predicted SOA mass and PM2.5 concentrations increase by up to 15% and 7%, respectively, for the high-NOxcase and up to 215% (~3 μg m−3) and 55%, respectively, for the low-NOx case. Percent bias between model-based and observationally-based secondary organic carbon (SOC) improved from −63% for the base case to −15% for the low-NOx case. The ability to robustly assign "best available" parameters in all volatile organic compound+oxidant systems, however, is critically limited due to insufficient data; particularly for photo-oxidation of diverse monoterpenes, sesquiterpenes, and alkanes under a range of atmospherically relevant conditions. Title: Analyzing Experimental Data and Model Parameters: Implications for Predictions of SOA Using Chemical Transport Models Author: Barsanti, Kelley, Carlton, Annmarie G., Chung, Serena H. Year: 2013 Despite critical importance for air quality and climate predictions, accurate representation of secondary organic aerosol (SOA) formation remains elusive. An essential addition to the ongoing discussion of improving model predictions is an acknowledgement of the linkages between experimental conditions, parameter optimization and model output, as well as the linkage between empirically-derived partitioning parameters and the physicochemical properties of SOA they represent in models. In this work, a "best available" set of SOA modeling parameters is selected by comparing predicted SOA yields and mass concentrations with observed yields and mass concentrations from a comprehensive list of published smog chamber studies. Evaluated SOA model parameters include existing parameters for two product (2p) and volatility basis set (VBS) modeling frameworks, and new 2p-VBS parameters; 2p-VBS parameters are developed to exploit advantages of the VBS approach within the computationally-economical and widely-used 2p framework. Fine particulate matter (PM2.5) and SOA mass concentrations are simulated for the continental United States using CMAQv.4.7.1; results are compared for a base case (with default CMAQ parameters) and two best available parameter cases to illustrate the high- and low-NOx limits of biogenic SOA formation from monoterpenes. Results are discussed in terms of implications for current chemical transport model simulations and recommendations are provided for future modeling and measurement efforts. The comparisons of SOA yield predictions with data from 22 published chamber studies illustrate that: (1) SOA yields for naphthalene, and cyclic and > C5 straight-chain/branched alkanes are not well represented using either the newly developed or existing parameters for low-yield aromatics and lumped alkanes, respectively; and (2) for four of seven volatile organic compound+oxidant systems, the 2p-VBS parameters better represent chamber data than do the default CMAQ v.4.7.1 parameters. Using the "best available" parameters (combination of published 2p and newly derived 2p-VBS), predicted SOA mass and PM2.5 concentrations increase by up to 15% and 7%, respectively, for the high-NOxcase and up to 215% (~3 μg m−3) and 55%, respectively, for the low-NOx case. Percent bias between model-based and observationally-based secondary organic carbon (SOC) improved from −63% for the base case to −15% for the low-NOx case. The ability to robustly assign "best available" parameters in all volatile organic compound+oxidant systems, however, is critically limited due to insufficient data; particularly for photo-oxidation of diverse monoterpenes, sesquiterpenes, and alkanes under a range of atmospherically relevant conditions. Close

• 28729. [Article] Netarts Bay, Oregon: an assessment of human impact on an estuarine system

  Problems associated with planning the future use of estuarine areas stem from: A lack of knowledge on the critical aspects of the system. Inability to predict the future changes which will occur within ...

  Citation × Citation Citation Abstract Copy Title: Netarts Bay, Oregon: an assessment of human impact on an estuarine system Author: McCallum, Larry D. Year: 1977 Problems associated with planning the future use of estuarine areas stem from: A lack of knowledge on the critical aspects of the system. Inability to predict the future changes which will occur within the system in order to effectively manage the resource base. These difficulties lie in the fact that changes within the system occur because of both "natural" and "cultural" conditions. The thesis hypothesis and subsequent research is to describe the physical changes that have occurred within the Netarts system, primarily due to man's impact. Types of data gathered for the analysis includes that on historical and current land use activities, current research findings on system characteristics, and independent research on shoreline changes and vegetation composition. Much of the historical data were taken from early manuscripts and publications. Current research data were obtained from several engineering studies of the bay, as well as a baseline study of Netarts funded by a grant from the National Science Foundation and Oregon State University. This study included an inventory of man's utilization of the resource base. Methods utilized in data analysis included aerial photo-interpretation, planimetric measurement of shoreline and vegetative alterations, and on-site inventory of current shoreline and vegetation changes. Results of the research have shown that it is possible to measure and describe changes within the Netarts Bay system. Specific findings include: A decrease in sandspit volume of nine percent between 1942 and 1974 due to construction of a boat basin and fill. Occurrence of marsh progradation in all marsh areas with sedge and low sand type showing the greatest increases between 1939-1962. A decrease in rate of marsh progradation from 1962-1974. A total decrease in tidal prism of the bay between 1957-1969 as measured by cross sectional areas. The rate of decrease is occurring at a faster rate south of the mouth of Whiskey Creek. Destruction of Chum salmon fisheries and native oyster populations due to over-harvesting and siltation. Destruction of Gaper clam beds along the eastern shore of the bay and increased erosion of the shore, due to road fill and road construction. The results of the research and subsequent findings show that it is possible to describe an estuary as a "system" that has applicability for future development of a land and water use model for an estuary. Title: Netarts Bay, Oregon: an assessment of human impact on an estuarine system Author: McCallum, Larry D. Year: 1977 Problems associated with planning the future use of estuarine areas stem from: A lack of knowledge on the critical aspects of the system. Inability to predict the future changes which will occur within the system in order to effectively manage the resource base. These difficulties lie in the fact that changes within the system occur because of both "natural" and "cultural" conditions. The thesis hypothesis and subsequent research is to describe the physical changes that have occurred within the Netarts system, primarily due to man's impact. Types of data gathered for the analysis includes that on historical and current land use activities, current research findings on system characteristics, and independent research on shoreline changes and vegetation composition. Much of the historical data were taken from early manuscripts and publications. Current research data were obtained from several engineering studies of the bay, as well as a baseline study of Netarts funded by a grant from the National Science Foundation and Oregon State University. This study included an inventory of man's utilization of the resource base. Methods utilized in data analysis included aerial photo-interpretation, planimetric measurement of shoreline and vegetative alterations, and on-site inventory of current shoreline and vegetation changes. Results of the research have shown that it is possible to measure and describe changes within the Netarts Bay system. Specific findings include: A decrease in sandspit volume of nine percent between 1942 and 1974 due to construction of a boat basin and fill. Occurrence of marsh progradation in all marsh areas with sedge and low sand type showing the greatest increases between 1939-1962. A decrease in rate of marsh progradation from 1962-1974. A total decrease in tidal prism of the bay between 1957-1969 as measured by cross sectional areas. The rate of decrease is occurring at a faster rate south of the mouth of Whiskey Creek. Destruction of Chum salmon fisheries and native oyster populations due to over-harvesting and siltation. Destruction of Gaper clam beds along the eastern shore of the bay and increased erosion of the shore, due to road fill and road construction. The results of the research and subsequent findings show that it is possible to describe an estuary as a "system" that has applicability for future development of a land and water use model for an estuary. Close

• 28730. [Article] Development of a Direct, Low Pressure, Laser-Induced Fluorescence Measurement Technique for NO2., Ambient Measurements and Urban NOx Chemistry

  Nitrogen oxides control the global formation of ozone in the lower atmosphere and influence the much higher levels of ozone formed in areas subjected to photochemical air pollution. As an important member ...

  Citation × Citation Citation Abstract Copy Title: Development of a Direct, Low Pressure, Laser-Induced Fluorescence Measurement Technique for NO2., Ambient Measurements and Urban NOx Chemistry Author: George, Linda Acha Year: 1991 Nitrogen oxides control the global formation of ozone in the lower atmosphere and influence the much higher levels of ozone formed in areas subjected to photochemical air pollution. As an important member of the nitrogen oxide family, N02 plays a significant role in serving as the only known source of ozone (through photolysis) in the lower atmosphere and as sink for HO via the formation of nitric acid. Ozone can be destroyed by reaction with another member of the nitrogen oxide family, nitric oxide (NO), to reform N02. This cycle between NO, N02 and 03 is known as the NOx-03 photostationary state (PSS). Imbalances in this cycle have been used to calculate ambient levels of oxidants (such as R02 and H02) responsible for ozone production. Consequently, accurate N02 measurements are critical to making meaningful measurements of the imbalances in the NOx-03 photostationary states (PSS). A low pressure laser-excited fluorescence technique (FAGE) for the direct determination of atmospheric N02 has been developed. This technique has been explored with both a Nd-YAG laser (1.4 W, 532nm, 30Hz) and a Cu-vapor (1.2 W, 511nm, 5.6kHz) laser. The detection limits for these instruments, under laboratory conditions and a signal collection time of 20s (lOs each signal and background), have been determined to be 450 and 350pptv N02, respectively. In these systems, the background was measured by chemically reducing N02 with FeS04°7H20. Ambient measurements of the NOx-03 photostationary state (PSS) were undertaken on a rooftop monitoring site in downtown Portland, Oregon. N02 was monitored with the Cu-vapor system. Nitric oxide and ozone were monitored with standard instruments. Data for three days in 1990 are presented. Overall these data sets clearly show that despite daily changes in concentration of NO, N02 and 0 3 of factors of 4-10 each, the PSS remains relatively constant to within -50%. This is in itself strong confIrmation of the primary importance of the NOx-03 photo stationary state in controlling the concentrations of these species at these levels. In addition, these experiments also serve to demonstrate that the monitoring instruments, including FAGE-N02, are not subject to serious interferences or artifacts at these concentration levels. Title: Development of a Direct, Low Pressure, Laser-Induced Fluorescence Measurement Technique for NO2., Ambient Measurements and Urban NOx Chemistry Author: George, Linda Acha Year: 1991 Nitrogen oxides control the global formation of ozone in the lower atmosphere and influence the much higher levels of ozone formed in areas subjected to photochemical air pollution. As an important member of the nitrogen oxide family, N02 plays a significant role in serving as the only known source of ozone (through photolysis) in the lower atmosphere and as sink for HO via the formation of nitric acid. Ozone can be destroyed by reaction with another member of the nitrogen oxide family, nitric oxide (NO), to reform N02. This cycle between NO, N02 and 03 is known as the NOx-03 photostationary state (PSS). Imbalances in this cycle have been used to calculate ambient levels of oxidants (such as R02 and H02) responsible for ozone production. Consequently, accurate N02 measurements are critical to making meaningful measurements of the imbalances in the NOx-03 photostationary states (PSS). A low pressure laser-excited fluorescence technique (FAGE) for the direct determination of atmospheric N02 has been developed. This technique has been explored with both a Nd-YAG laser (1.4 W, 532nm, 30Hz) and a Cu-vapor (1.2 W, 511nm, 5.6kHz) laser. The detection limits for these instruments, under laboratory conditions and a signal collection time of 20s (lOs each signal and background), have been determined to be 450 and 350pptv N02, respectively. In these systems, the background was measured by chemically reducing N02 with FeS04°7H20. Ambient measurements of the NOx-03 photostationary state (PSS) were undertaken on a rooftop monitoring site in downtown Portland, Oregon. N02 was monitored with the Cu-vapor system. Nitric oxide and ozone were monitored with standard instruments. Data for three days in 1990 are presented. Overall these data sets clearly show that despite daily changes in concentration of NO, N02 and 0 3 of factors of 4-10 each, the PSS remains relatively constant to within -50%. This is in itself strong confIrmation of the primary importance of the NOx-03 photo stationary state in controlling the concentrations of these species at these levels. In addition, these experiments also serve to demonstrate that the monitoring instruments, including FAGE-N02, are not subject to serious interferences or artifacts at these concentration levels. Close