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  • GEOPHYSICS  (5)
  • 1990-1994  (5)
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  • 1
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    On the age of stratospheric air and ozone depletion potentials in polar regions (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Observations of the nearly inert, man-made chlorofluorocarbon CFC-115 obtained during January 1989 are used to infer the age of air in the lower stratosphere. These observations together with estimated release rates suggest an average age of high-latitude air at pressure altitudes near 17-21 km of about 3 to 5 yr. This information is used together with direct measurements of HCFC-22, HCFC-142b, CH3Br, H-1301, H-1211, and H-2402 to examine the fractional dissociation of these species within the Arctic polar lower stratosphere compared to that of CFC-11 and hence to estimate their local ozone depletion potentials in this region. It is shown that these HCFCs are much less efficiently dissociated within the stratosphere than CFC-11, lowering their ozone depletion potentials to only about 30-40 percent of their chlorine loading potentials. In contrast, the observations of CH3Br and the Halons considered confirm that they are rapidly dissociated within the stratosphere, with important implications for their ozone depletion potentials.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 97; D12,; 12
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    A comparison of ER-2 measurements of stratospheric water vapor between the 1987 Antarctic and 1989 Arctic Airborne missions (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Vertical profiles of water vapor inside the Antarctic vortex have been compared with those taken outside it over Punta Arenas (53 deg S, 71 deg W). A similar exercise was performed with Arctic vortex profiles and those taken over Stavanger (59 deg N, 6 deg E). Residual water, defined as the stratospheric water vapor mixing ratio with the contribution from methane oxidation subtracted, is also shown as profiles inside and outside the vortex for both missions. The Arctic and Antarctic profiles of water vapor and residual water are compared. Locally dehydrated air was evident both inside and outside the Antarctic vortex, but such dehydration was not evident in and around the Arctic vortex. Arctic profiles of residual water are consistent with nontropical entry for some air.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters, Supplement (ISSN 0094-8276); 17; 465-468
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    NASA TECHNICAL REPORTS
  • 3
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    Redistribution of reactive odd nitrogen in the lower arctic stratosphere (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: In-situ measurements of total reactive odd nitrogen NO(y), were made from the NASA DC-8 aircraft in the lower arctic stratosphere during the 1989 Airborne Arctic Stratospheric Expedition. Throughout January and February, NO(y) mixing ratios were typically between 0.5 and 3 parts per billion by volume (ppbv) at altitudes between 10 and 12.5 km. During several flights late in the mission, events of unusually light NO(y) occurred with mixing ratios up to 12 ppbv at these altitudes. Simultaneous measurements of N2O, O3, and H2O during these events suggest that large changes in NO(y) are not expected. The elevated NO(y) values are interpreted as a vertical redistribution of NO(y) in the lower stratosphere resulting from gravitational sedimentation of aerosol particles containing HNO3. No evidence of the redistribution of H2O is noted, consistent with observations of denitrification without dehydration higher in the stratosphere.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters, Supplement (ISSN 0094-8276); 17; 453-456
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    NASA TECHNICAL REPORTS
  • 4
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    Measurements of ClO and O3 from 21 deg N to 61 deg N in the lower stratosphere during February 1988 - Implications for heterogeneous chemistry (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The decline in stratospheric ozone at northern midlatitudes in wintertime may be caused by chlorine photochemistry that has been enhanced by heterogeneous reactions. The possibility that the heterogeneous reaction of N2O5 on sulfate aerosols is the cause of this decadal ozone decline is examined by comparing ClO and O3 measurements made in the lower stratosphere during February, 1988, with results from a 2D model. At midlatitudes, the abundances, latitudinal, and seasonal gradients of the observed ClO are similar to the results of a model with heterogeneous chemistry, but are in strong disagreement with the results from the model with only gas-phase chemistry. At low latitudes, agreement is best with the results of the model with only gas-phase chemistry. Limited observations indicate that the amount of reactive chlorine is being enhanced, and that heterogeneous chemistry is a likely cause.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 18; 2273-227
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    NASA TECHNICAL REPORTS
  • 5
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    Measurements of halogenated organic compounds near the tropical tropopause (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: The amount of organic chlorine and bromine entering the stratosphere have a direct influence on the magnitude of chlorine and bromine catalyzed ozone losses. Twelve organic chlorine species and five organic bromine species were measured from 12 samples collected near the tropopause between 23.8 deg N and 25.3 deg N during AASE 2. The average mixing ratios of total organic chlorine and total organic bromine were 3.50 +/- 0.06 ppbv and 21.1 +/- 0.8 pptv, respectively. CH3Cl represented 15.1% of the total organic chlorine, with CFC 11 (CCl3F) and CFC 12 (CCl2F2) accounting for 22.6% and 28.2%, respectively, with the remaining 34.1% primarily from CCl4, CH3CCl3, and CFC 113 (CCl2FCClF2). CH3Br represented 54% of the total organic bromine. The 95% confidence intervals of the mixing ratios of all but four of the individual compounds were within the range observed in low and mid-latitude mid-troposphere samples. The four compounds with significantly lower mixing ratios at the tropopause were CHCl3, CH2Cl2, CH2Br2, and CH3CCl3. The lower mixing ratios may be due to entrainment of southern hemisphere air during vertical transport in the tropical region and/or to exchange of air across the tropopause between the lower stratosphere and upper troposphere.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 20; 22; p. 2567-2570
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