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  • 1
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    Effects of Pinatubo aerosol on stratospheric ozone at mid-latitudes (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Mid-latitude ozone data from ER-2 aircraft measurements in 1989, 1991, and 1992 were examined to determine how sulfate aerosols from the eruption of Mt. Pinatubo had affected ozone at about 18 km. N2O was used as a tracer to help distinguish between chemical and dynamical aerosol effects. At 20-45 deg N in February 1992, ozone was about 10-20% lower than February 1989 and 1991, with respect to N2O. Data from Aug. 1991 - Mar. 1992 showed changes in ozone with respect to N2O, but the magnitude of those changes was not correlated with the magnitude of the changes in aerosol surface area density.
    Keywords: ENVIRONMENT POLLUTION
    Type: Geophysical Research Letters (ISSN 0094-8276); 20; 22; p. 2515-2518
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Interpretation of NO(x)/NO(y) observations from AASE-2 using a model of chemistry along trajectories (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: In situ measurements of NO and NO(y) are used to derive the ratio NO(x)/NO(y) along the flight track of the NASA ER-2 aircraft. Data are presented for two flights at midlatitudes in October 1991 during the Airborne Arctic Stratospheric Expedition-2 (AASE-2). Aerosol particle surface area was concurrently measured. The observations are compared with a photochemical model integrated along back trajectories from the aircraft flight track. Comparison of observations with the model run along trajectories and at a fixed position clearly and quantitatively demonstrates the importance of an air parcel's dynamic history in interpretation of local chemical observations. Comparison of the data with model runs under different assumptions regarding heterogeneous chemistry further reinforces the case for occurrence of the reaction of N2O5 + H2O on sulfate aerosol surfaces in the atmosphere. Finally, comparisons for which relative changes in the model and the data are not consistent caution that our ability to resolve all the observations is not yet complete.
    Keywords: ENVIRONMENT POLLUTION
    Type: Geophysical Research Letters (ISSN 0094-8276); 20; 22; p. 2507-2510
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    NASA TECHNICAL REPORTS
  • 3
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    In-situ measurements of total reactive nitrogen, total water vapor, and aerosols in polar stratospheric clouds in the Antarctic stratosphere (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Measurements of total reactive nitrogen, NOy, total water vapor, and aerosols were made as part of the Airborne Antarctic Ozone Experiment. The measurements were made using instruments located onboard the NASA ER-2 aircrafts which conducted twelve flights over the Antarctic continent reaching altitudes of 18 km at 72 S latitude. Each instrument utilized an ambient air sample and provided a measurement up to 1 Hz or every 200 m of flight path. The data presented focus on the flights of Aug. 17th and 18th during which Polar Stratospheric Clouds (PSCs) were encountered containing concentrations of 0.5 to 1.0 micron diameter aerosols greater than 1 cm/cu. The temperature pressure during these events ranged as low as 184 K near 75 mb pressure, with water values near 3.5 ppm by volume (ppmv). With the exception of two short periods, the PSC activity was observed at temperatures above the frost point of water over ice. The data gathered during these flights are analyzed and presented.
    Keywords: ENVIRONMENT POLLUTION
    Type: NASA, Goddard Space Flight Center, Polar Ozone Workshop. Abstracts; p 75-76
    Format: application/pdf
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  • 4
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    Observations of condensation nuclei in the 1987 airborne Antarctic ozone experiment (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The condensation nucleus counter (CNC) flown of the NASA ER-2 in the Airborne Antarctic Ozone Experiment provides a measurement of the number mixing ratio of particles which can be grown by exposure to supersaturated n-butyl alcohol vapor to diameters of a few microns. Such particles are referred to as condensation nuclei (CN). The ER-2 CNC was calibrated with aerosols of known size and concentration and was found to provide an accurate measure of the number concentration of particles larger than about 0.02 micron. Since the number distribution of stratospheric aerosols is usually dominated by particles less than a few tenths of micron in diameter, the upper cutoff of the ER-2 CNC has not been determined experimentally. However, theory suggests that the sampling and counting efficiency should remain near one for particles as large as 1 micron in diameter. Thus, the CN mixing ratio is usually a good measure of the mixing ratio of submicron particles.
    Keywords: ENVIRONMENT POLLUTION
    Type: NASA, Goddard Space Flight Center, Polar Ozone Workshop. Abstracts; p 108-112
    Format: application/pdf
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  • 5
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    Performance of a focused cavity aerosol spectrometer for measurements in the stratosphere of particle size in the 0.06-2.0-micrometer-diameter range (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A focused cavity aerosol spectrometer aboard a NASA ER-2 high-altitude aircraft provided high-resolution measurements of the size of the stratospheric particles in the 0.06-2.0-micrometer-diameter range in flights following the eruption of Mount Pinatubo in 1991. Effects of anisokinetic sampling and evaporation in the sampling system were accounted for by means adapted and specifically developed for this instrument. Calibrations with monodisperse aerosol particles provided the instrument's response matrix, which upon inversion during data reduction yielded the particle size distributions. The resultant dataset is internally consistent and generally shows agreement to within a factor of 2 with comparable measurements simultaneously obtained by a condensation nuclei counter, a forward-scattering spectrometer probe, and aerosol particle impactors, as well as with nearby extinction profiles obtained by satellite measurements and with lidar measurements of backscatter.
    Keywords: ENVIRONMENT POLLUTION
    Type: Journal of Atmospheric and Oceanic Technology (ISSN 0739-0572); 12; 1; p. 115-129
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    NASA TECHNICAL REPORTS
  • 6
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    FTIR studies of low temperature sulfuric acid aerosols (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: Sub-micrometer sized sulfuric acid H2SO4 particles were generated using a constant output atomizer source. The particles were then exposed to water vapor before being injected into a low temperature cell. Multipass transmission Fourier Transformation Infrared (FTIR) spectroscopy was used to determine the phase and composition of the aerosols as a function of time for periods of up to five hours. Binary H2SO4H2O aerosols with compositions from 35 to 95 wt % H2SO4 remained liquid for over 3 hours at room temperatures ranging from 189-240 K. These results suggest that it is very difficut to freeze SSAs via homogeneous nucleation. Attempts to form aerosols more dilute than 35 wt % H2SO4 resulted in ice formation.
    Keywords: ENVIRONMENT POLLUTION
    Type: Geophysical Research Letters (ISSN 0094-8276); 22; 9; p. 1105-1108
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    NASA TECHNICAL REPORTS
  • 7
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    In-situ measurements of changes in stratospheric aerosol and the N2O-aerosol relationship inside and outside of the polar vortex (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: Two optical particle counters on the ER-2, together covering a particle size diameter range from 0.1 microns to 23 microns, were used to measure the aerosol bulk quantities integral number, aerosol surface and volume, as well as detailed size distributions inside and outside of the polar vortex in the lower stratosphere. While AAES I (Arctic Airborne Stratospheric Expedition, (Dec. 88 - Feb. 89) was conducted in a period of relative volcanic quiescence, enhancements in aerosol number, surface and volume of factors around 10, 25 and 100 were observed during AASE 2 (Aug. 91 - Mar. 92) due to the eruption of Mt. Pinatubo. The changes in these bulk quantities as well as in the size distributions measured both outside and inside the polar vortex are presented and compared with those obtained in polar stratospheric cloud events (AASE I). Except for a shift towards larger aerosol mixing ratios the general shape of correlograms between the measured N2O and particle mixing ratios remain similar before and after the eruption. Similar correlograms are used to interpret data from vertical profiles inside and outside of the polar vortex.
    Keywords: ENVIRONMENT POLLUTION
    Type: Geophysical Research Letters (ISSN 0094-8276); 20; 22; p. 2559-2562
    Format: text
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