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  • 1
    ISSN: 1573-0662
    Keywords: J NO 2 ; NO2 photolysis ; atmospheric photochemistry ; J NO 2measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract An instrument, specifically designed for measurements from a balloon platform in the stratosphere, has been used to obtain ground-level values of the atmospheric photodissociation coefficient of nitrogen dioxide, J NO 2.A typical clear-sky value is 8.0×10-3 s-1 when the solar zenith angle is 40°. Measurements were made as a function of solar zenith angle and correlated with a calibrated Eppley UV radiometer. It is shown that J NO 2may be expressed as a simple function of the radiometer output so that estimates of J NO 2can be made using just an upward looking radiometer to an accuracy of about 20%. The measurements are also found to be in good agreement with calculations of J NO 2using a simplified isotropic multiple scattering computer routine.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-0662
    Keywords: J NO 2 ; NO2 photolysis ; atmospheric photochemistry ; J NO 2 measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The photodissociation coefficient of NO2, J NO 2, has been measured from a balloon platform in the stratosphere. Results from two balloon flights are reported. High Sun values of J NO 2 measured were 10.5±0.3 and 10.3±0.3×10-3 s-1 at 24 and 32 km respectively. The decrease in J NO 2 at sunset was monitored in both flights. The measurements are found to be in good agreement with calculations of J NO 2 using a simplified isotropic multiple scattering computer routine.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2005-06-09
    Description: We survey measurements of stratospheric NO(y) on the NASA DC-8 during AASE 2 in early 1992. Emphasis is on correlations with other long-lived species: O3, N2O, and CH4. No cases of extremely high NO(y)/O3 ratios were seen in 1992. This suggests that denitrification at higher altitudes was less pervasive than in 1989. Values of NO(y)/O3 in 1992 are comparable to, though perhaps lower than, those measured in 1989. The correlation of NO(y) with N2O changes over the course of the mission. Relative to the correlation for the whole season, low values of NO(y) occur in February, most notably on the 22nd. The reason for the low NO(y) is unknown It is generally too warm at DC-8 altitudes for the presence of PSC particles, but denitrification at higher altitudes, followed by descent, might account for the low values seen on 22 February. However, this may be unlikely since the NASA ER-2, flying during the same period, saw no evidence of denitrification at higher altitudes.
    Keywords: Environment Pollution
    Type: Airborne Arctic Stratospheric Expedition 2 Air Parcel Trajectories (ISSN 0094-8534); Volume 20; No. 22; 2563-2566; NASA-TM-112699
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  • 4
    Publication Date: 2005-06-09
    Description: We report in situ stratospheric measurements of CH4, N2O, and O3 obtained aboard the NASA DC-8 during the January-March 1992 Airborne Arctic Stratospheric Expedition II field campaign. These data demonstrate a strong linear correlation between N2O and CH4 in the lower stratosphere thus indicating that both species are effective tracers of stratospheric air motion. Measurements of both species on constant geometric height surfaces indicate that significant subsidence of the arctic stratospheric air mass occurred at DC-8 altitudes over the course of the AASE-II expedition. In addition, a widespread reduction in O3 mixing ratios (up to 20%) relative to these conserved tracers was also observed in the lower stratosphere in March a compared to January and February results.
    Keywords: Environment Pollution
    Type: Airborne Arctic Stratospheric Expedition 2 Air Parcel Trajectories (ISSN 0094-8534); Volume 20; No. 22; 2543-2546; NASA-TM-112699
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  • 5
    Publication Date: 2019-07-13
    Description: The redistribution of HNO3 via uptake and sedimentation by cirrus cloud particles is considered an important term in the upper tropospheric budget of reactive nitrogen. Numerous cirrus cloud encounters by the NASA WB-57F high-altitude research aircraft during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) were accompanied by the observation of condensed-phase HNO3 with the NOAA chemical ionization mass spectrometer. The instrument measures HNO3 with two independent channels of detection connected to separate forward and downward facing inlets that allow a determination of the amount of HNO3 condensed on ice particles. Subtropical cirrus clouds, as indicated by the presence of ice particles, were observed coincident with condensed-phase HNO3 at temperatures of 197-224 K and pressures of 122-224 hPa. Maximum levels of condensed-phase HNO3 approached the gas-phase equivalent of 0.8 ppbv. Ice particle surface coverages as high as 1.4 # 10(exp 14) molecules/ square cm were observed. A dissociative Langmuir adsorption model, when using an empirically derived HNO3 adsorption enthalpy of -11.0 kcal/mol, effectively describes the observed molecular coverages to within a factor of 5. The percentage of total HNO3 in the condensed phase ranged from near zero to 100% in the observed cirrus clouds. With volume-weighted mean particle diameters up to 700 ?m and particle fall velocities up to 10 m/s, some observed clouds have significant potential to redistribute HNO3 in the upper troposphere.
    Keywords: Environment Pollution
    Type: Journal of Geophysical Research (ISSN 0148-0227); 109
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  • 6
    Publication Date: 2019-07-13
    Description: During October 19-20, 1991, one flight of the NASA Global Tropospheric Experiment (GTE) Pacific Exploratory Mission (PEM-West A) mission was conducted near Hawaii as an intercomparison with ground-based measurements of the Mauna Loa Observatory Photochemistry Experiment (MLOPEX 2) and the NOAA Climate Modeling and Diagnostics Laboratory (CMDL). Ozone, reactive nitrogen species, peroxides, hydrocarbons, and halogenated hydrocarbons were measured by investigators aboard the DC-8 aircraft and at the ground site. Lidar cross sections of ozone revealed a complex air mass structure near the island of Hawaii which was evidenced by large variation in some trace gas mixing ratios. This variation limited the time and spatial scales for direct measurement intercomparisons. Where differences occurred between measurements in the same air masses, the intercomparison suggested that biases for some trace gases was due to different calibration scales or, in some cases, instrumental or sampling biases. Relatively large uncertainties were associated with those trace gases present in the low parts per trillion by volume range. Trace gas correlations were used to expand the scope of the intercomparison to identify consistent trends between the different data sets.
    Keywords: Environment Pollution
    Type: Paper 96JD00213 , Journal of Geophysical Research (ISSN 0148-0227); 101; D9; 14,599-14,612
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