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  • 1
    Publication Date: 2011-08-24
    Description: Laboratory experiments to quantify the global production of NOx (NO + NO2) in the troposphere due to atmospheric lightning and biogenic activity in soil are presented. These laboratory experiments, as well as other studies, suggest that the global production of NOx by lightning probably ranges between 2 and 20 MT(N)y-1 of NO and is strongly dependent on the total energy deposited by lightning, a quantity not well-known. In our laboratory experiments, nitrifying micro-organisms is soil were found to be a significant source of both NO and nitrous oxide (N2O). The measured production ratio of NO to N2O averaged 2-3 for oxygen partial pressures of 0.5-10%. Extrapolating these laboratory measurements to the global scale, which is somewhat risky, suggests that nitrifying micro-organisms in soil may account for as much as 10 MT(N) y-1 of NO. Additional experiments with denitrifying micro-organisms gave an NO to N2O production ratio ranging from 2 to 4 for an oxygen partial pressure of 0.5% and a ratio of less than unity for oxygen partial pressures ranging from 1 to 20%. The production of NO and N2O, normalized with respect to micro-organism number indicates that the production of both NO and N2O by denitrifying micro-organisms is at least an order of magnitude less than production by nitrifying micro-organisms for the micro-organisms studied.
    Keywords: Meteorology and Climatology
    Type: Atmospheric environment (ISSN 0004-6981); Volume 18; 9; 1797-804
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  • 2
    Publication Date: 2011-08-19
    Description: Results are reported on the performance of (1) denuder-tube/chemiluminescent, (2) nylon-filter/ion-chromatography, and (3) tunable-diode-laser/multipath-absorption HNO3 measurement instruments during the NASA Global Tropospheric Experiment Chemical Instrumentation Test and Evaluation 2 (CITE 2) program in summer 1986. The instrument designs, test protocols, and CITE 2 flights are described, and the results are presented in extensive graphs and discussed in detail. The data obtained with the three instruments are shown to be in very poor agreement at mixing ratios below 150 parts per trillion by volume (pptv), with significant discrepancies even at higher levels. Instrument (3) gave systematically higher values than (1) and (2). It is concluded that none of the instruments is accurate enough for reliable use at normal atmospheric HNO3 levels (around 100 pptv).
    Keywords: AIRCRAFT INSTRUMENTATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 10089-10
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  • 3
    Publication Date: 2011-08-19
    Description: Results on NO2 instruments are reported from the NASA Global Tropospheric Experiment Chemical Instrumentation Test and Evaluation 2 (CITE 2) program in summer 1986. The instruments tested were (1) a two-photon LIF system using a laser for NO2-NO photolysis, (2) a chemiluminescence (CL) detector using FeSO4 for NO2-NO conversion, (3) a CL detector using an arc lamp for NO2-NO photolysis, and (4) a tunable-laser-diode multipath-absorption system. The procedures for the CITE 2 ground-based and flight tests are described in detail, and the results are presented in extensive graphs. Instrument (2) was eliminated because the FeSO4 converted atmospheric PAN to NO, resulting in spuriously high NO2 values. The remaining instruments gave readings in 30-40-percent agreement at NO2 mixing ratios of 100-200 parts per trillion by volume (pptv). At ratios below 50 pptv, the correlation among the measurements was very poor, with a tendency for system (4) to give higher values than (1) or (3).
    Keywords: AIRCRAFT INSTRUMENTATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 10103-10
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  • 4
    Publication Date: 2011-08-19
    Description: Laboratory tests were performed to quantify the expected NO(x) production by lightning and biological processes. Attention was focused on energy deposition by lightning and the oxygen partial pressure of soil, and one-dimensional photochemical models were defined for the tropospheric distributions of NO and HNO3 for various NO source strengths. The Lightning Facility data were compared with air samples of N2O production gathered during over 2 yr of flights through storms. Soil NO(x) productions were studied in terms of nitrification processes involving Nitrosomonas europaea and Alcaligenes faecalis bacteria, which change ammonium to nitrite and release NO and N2O as byproducts. The results indicate that atmospheric NO(x) is generated at two tropospheric levels, with lightning and soil bacteria being significant contributors.
    Keywords: GEOPHYSICS
    Type: Atmospheric Environment (ISSN 0004-6981); 18; 9, 19
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  • 5
    Publication Date: 2011-08-16
    Description: Doppler effect induced small spectral line shifts measured by modified duochromator in MPD arc jet
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: ; ADEMIE DES SCIENCES
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  • 6
    Publication Date: 2011-08-16
    Keywords: MASERS
    Type: Journal of Chemical Physics; 58; Apr. 1
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  • 7
    Publication Date: 2011-08-16
    Description: High-resolution measurements of SO2 absorption coefficients in the UV are presented in the wavelength interval between 2962 and 3011 A using a frequency-doubled dye laser as the radiation source. These measurements have application to pollution monitoring of SO2 using the differential absorption scattering (DAS) technique. The spectral resolution of the measurements was 0.2 A (determined by the linewidth of the dye laser) and the generated spectra exhibited considerable rotational structure on the (000) double prime to (060) prime, (070) prime, and (080) prime electronic-vibrational transitions. The latter transitions correspond to center wavelengths of 3001.8, 2981.0, and 2962 A, respectively. The laser measurements were obtained with a signal-processing technique which eliminated calibration procedures associated with conventional optical-absorption measurements. Using this technique, the statistical uncertainty associated with measured absorption coefficients has been reduced to less than plus or minus 2% with a wavelength uncertainty of the laser source of plus or minus 0.1 A.
    Keywords: ENVIRONMENT POLLUTION
    Type: Journal of Applied Physics; 46; July 197
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  • 8
    Publication Date: 2011-08-17
    Description: Laser heterodyne spectroscopy (LHS) techniques were used to measure radical gases from Spacelab. Major emphasis was placed on the measurement of ClO, ClOnO2, HO2, H2O2, N2O5, and HOCl in solar occultation with vertical resolution less than or equal to 2-km and vertical range from 1O to 70-km. Sensitivity analyses were performed on ClO and O3 to determine design criteria for the LHS instrument. Results indicate that O3 and ClO vertical profiles can be measured with an accuracy more than or equal to 95% and more than or equal to 80%, respectively, over the total profile.
    Keywords: GEOPHYSICS
    Type: High Resolution Infrared Spectry. Tech. for Upper Atmospheric Meas.; p 55-79
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  • 9
    Publication Date: 2011-08-19
    Description: Results from an intercomparison of techniques to measure tropospheric levels of carbon monoxide (CO) are discussed. The intercomparison was conducted as part of the National Aeronautics and Space Administration's Global Tropospheric Experiment (GTE) and was held at Wallops Island, VA, in July 1983. Instruments intercompared included a laser differential absorption method and three grab sample/gas chromatograph methods. The intercomparison consisted of simultaneous measurements of ambient levels of CO and controlled injections of CO from a common manifold. Results from the techniques exhibited a high degree of correlation among themselves and with changes in the CO mixing ratio. The results suggested a level of agreement among the techniques of about 15 percent. However, a day-to-day bias between the techniques was observed, which resulted in differences between techniques as large as 38 percent.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 12
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  • 10
    Publication Date: 2011-08-19
    Description: Results from an intercomparison of techniques to measure tropospheric levels of nitric oxide (NO) are discussed. The intercomparison was part of the National Aeronautics and Space Administration's Global Tropospheric Experiment and was conducted at Wallops Island, VA, in July 1983. Instruments intercompared included a laser-induced fluorescence system and two chemiluminescence instruments. The intercomparisons were performed with ambient air at NO mixing ratios ranging from 10 to 60 pptv and NO-enriched ambient air at mixing ratios from 20 to 170 pptv. All instruments sampled from a common manifold. The techniques exhibited a high degree of correlation among themselves and with changes in the NO mixing ratio. Agreement among the three techniques was placed at approximately + or - 30 percent. Within this level of agreement, no artifacts or species interferences were identified.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 12
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