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  • 1
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    An intercomparison of carbon monoxide, nitric oxide, and hydroxyl measurement techniques - Overview of results (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Results from an intercomparison of methods to measure carbon monoxide (CO), nitric oxide (NO), and the hydroxyl radical (OH) are discussed. The intercomparison was conducted at Wallops Island, Virginia, in July 1983 and included a laser differential absorption and three grab sample/gas chromatograph methods for CO, a laser-induced fluorescence (LIF) and two chemiluminescence methods for NO, and two LIF methods and a radiocarbon tracer method for OH. The intercomparison was conducted as a field measurement program involving ambient measurements of CO (150-300 ppbv) and NO (10-180 pptv) from a common manifold with controlled injection of CO in incremental steps from 20 to 500 ppbv and NO in steps from 10 to 220 pptv. Only ambient measurements of OH were made. The agreement between the techniques was on the order of 14 percent for CO and 17 percent for NO. Hardware difficulties during the OH tests resulted in a data base with insufficient data and uncertanties too large to permit a meaningful intercomposition.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 11819-11
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  • 2
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    Two-photon laser-induced fluorescence detection of OH (1986)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The TP-LIF OH sensor is based on the principle that a molecule having multiple energy states, all of which are bonding, can be pumped into the highest state with the resulting fluorescence being blue-shifted relative to all pumping wavelengths. In this way, one can successfully discriminate against virtually all noise sources in the system using long wavelength blocking filters in conjunction with solar-blind photomultiplier tubes. Thus, these systems tend to be signal limited rather than signal-to-noise limited as is true of the SP-LIF technique as well as other conventional analytical methods. The trick to achieving the above sampling scheme, with high efficiency, is in the use of high photon fluxes of short time duration. Obviously, the latter type of light source is fulfilled nicely by available pulsed lasers. From an operational point of view, however, this laser source needs to be tunable. The latter characteristic permits extremely high selectivity for the detection of a diatomic or simple polyatomic molecule by taking advantage of the high-resolution spectroscopic features of these type species.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Research Center Future Directions for H sub x O sub y Detection; p 37-38
    Format: application/pdf
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  • 3
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    Summertime photochemistry of the troposphere at high northern latitudes (1992)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: Budgets of O3, NO(x), and NO(y), and acetic acid in the Arctic Boundary Layer Expedition (ABLE 3A) flight region are constructed using photochemical model statistics based on aircraft observations. A Lagrangian model is used to reconstruct the photochemical history of two aged biomass fire plumes sampled by the ABLE 3A aircraft. It is shown that anthropogenic influence on O3 levels in the Arctic may manifest itself not by long-range transport of pollution-derived O3, but rather by a decrease of the regional photochemical sink due to the presence of small amounts of NO(x). The low concentrations of NO(x) measured in ABLE 3A were sufficient to reduce the rate of photochemical loss appreciably relative to a NO(x)-free atmosphere, thus increasing the O3 lifetime. It is shown that decomposition of PAN can account for most of the NO(x) measured below 4-km altitude, but for only 20 percent at 6-km altitude. A lifetime of 29 days is estimated for NO(y) in the ABLE 23A flight region.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 97; D15; p. 16,421-16,431.
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  • 4
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    Summertime tropospheric observations related to N(x)O(y) distributions and partitioning over Alaska - Arctic Boundary Layer Expedition 3A (1992)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: Measurements of NO, NO2, PAN and NO(y) are presented for the summertime middle/lower troposphere over northern high latitudes. Chemical signatures from concurrent measurements of O3, CO, C2H2, C2H6, C3H8, C2Cl4, and H2O are used to characterize factors affecting the budget and distribution of N(x)O(y) in the Arctic and Sub-Arctic tropospheric air masses sampled over Alaska during the NASA Arctic Boundary Layer Expedition (ABLE 3A). The results implicate biomass burning in Siberia as the probable source of about one-third of the NO(y) abundance within the middle lower troposphere over Alaska and the downward transport of air from altitude in the vicinity of the tropopause as a major contributor to the abundance of NO(y) within the lower 6 km column over Alaska.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 97; D15; p. 16,481-16,509.
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  • 5
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    Observed and model-calculated NO2/NO ratios in tropospheric air sampled during the NASA GTE/CITE-2 field study (1990)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Airborne measurements of NO2/NO ratios in the free troposphere, obtained using two-photon LIF (TP-LIF) and chemiluminescence (CL) detectors during the NASA Global Tropospheric Experiment Chemical Instrumentation Test and Evaluation 2 (CITE 2) program in summer 1986, are analyzed and compared with the predictions of a photochemical model. The derivation of the model is outlined, with an emphasis on the role of peroxy radicals in the fast photochemical cycling of NO and NO2 and the production of O3; the CITE 2 instruments and flight protocols are described; and the results are presented in extensive tables and graphs and discussed in detail. It was found that on three CITE 2 flights the CL data were systematically greater than the TP-LIF data; when these data were removed, the averaged values of the two instruments agreed to within 1 percent. The NO2/NO ratios predicted by the model are shown to be consistent with the measurements, although usually 20-25 percent lower.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 10235-10
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  • 6
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    Free tropospheric and boundary layer measurements of NO over the central and eastern North Pacific Ocean (1987)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Reported in this paper are the Georgia Institute of Technology NO results from the fall 1983 NASA GTE/CITE 1 Airborne Field Sampling Program. These data were predominantly collected over a geographical area defined by the eastern and central North Pacific Ocean, spanning the latitude range of 15-42 deg N. These NO measurements were taken using the two-photon laser-induced fluorescence technique. The data show a general trend of increasing levels of NO from the boundary layer up to altitudes of nearly 10 km. The average midday value of NO at altitudes of less than or equal to 1.8 km was 4 parts per trillion by volume (pptv), and at about 6 km, 20 pptv, whereas that at about 9 km was 25-35 pptv, the higher value reflecting the inclusion of NO data collected from the outflow region of two electrically active cumulonimbus clouds. The high-altitude NO data strongly suggest that at least during the time of the GTE flight operation, the major sources of NO for remote regions of the Pacific Ocean were those resulting from lightning and the downward transport of stratospheric air.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 2049-207
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  • 7
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    An estimate of the NO(x) production rate in electrified clouds based on NO observations from the GTE/CITE 1 fall 1983 field operation (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: During the NASA GTE/CITE 1 fall 1983 airborne field operation the NASA Convair 990 penetrated the anvils of two active cumulonimbus clouds. While NO levels outside the anvils averaged about 20 parts per trillion per volume (pptv), the average NO inside the anvils was about 440 pptv. Extrapolation of this observation along with data on the amount of air typically advected out of cumulonimbus clouds and the total number of thunderclouds occurring over the globe at any moment, implies a rate of nitrogen fixation in electrified clouds of about 7 x 10 to the 6th trillion/yr. Although the data base used to make this estimate is quite limited, the approach differs from that used in previous studies of the global production of nitrogen oxides by lightning, and thus represents an independent assessment of the role of electrified clouds in the atmospheric nitrogen oxide budget.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 2153-215
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  • 8
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    Net ozone photochemical production over the eastern and central North Pacific as inferred from GTE/CITE 1 observations during fall 1983 (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The role of photochemistry in the budget of tropospheric ozone is studied. Measurements of O3, NO, CO, H2O vapor, and temperature obtained during the fall of 1983 during the GTE/CITE project over the eastern and central North Pacific Ocean are analyzed. The effect of altitude on the measurements is discussed. The analysis reveals a correlation between ozone and NO levels; both increase in concentration and variability with altitude. It is observed that an additional source of secondary importance associated wih CO-rich air parcels exists. A photochemical model is utilized to calculate the net rate of ozone production by photochemical reactions. A net photochemical source of ozone in the free troposphere and a net sink in the boundary layer are detected. The relation between the ozone source in the free troposphere and NO is examined. It is estimated that photochemistry provides a net ozone source to the free troposphere overlying the eastern and central North Pacific Ocean of about 5 x 10 to the 10th molecules/sq cm sec and a net sink of ozone to the boundary layer overlying this region of about 3 x 10 to the 10th molecules/sq cm sec.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 2131-215
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