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  • 1
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    Extremely low N2O concentrations in the springtime stratosphere at McMurdo Station, Antarctica (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Measurements have been made of stratospheric N2O using the Stony Brook millimeter-wave remote sensing spectrometer at McMurdo Station, and NO2 mixing ratios are found that are less than 1.5 at 20 km and less than 1.10 at 25 km compared to values measured during the Antarctic summer. The observed mixing ratios are also much less than those predicted by global-scale models of stratospheric chemistry and dynamics. As the NO2 signal remained very weak when McMurdo was at the edges of the ozone hole and showed no signs of recovering during October, it is concluded that the geographical and temporal extent of the region of low NO2 is comparable to or greater than that of the ozone hole. These results argue against theories that require springtime upwelling to explain the Antarctic ozone hole. It is suggested that the air in the Antarctic lower stratosphere during late winter and early spring has been subjected to considerable downward transport.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 53-55
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  • 2
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    A ground-based technique for millimeter wave spectroscopic observations of stratospheric trace constituents (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent concern over possible long term stratospheric changes caused by the introduction of man-made compounds has increased the need for instrumentation that can accurately measure stratospheric minor constituents. The technique of radio spectroscopy at millimeter wavelengths was first used to observe rotational transitions of stratospheric ozone nearly two decades ago, but has not been highly developed until recently. A ground-based observing technique is reported which employs a millimeter-wave superheterodyne receiver and multichannel filter spectrometer for measurements of stratospheric constituents that have peak volume mixing ratios that are less than 10 to the -9th, more than 3 orders of magnitude less than that for ozone. The technique is used for an extensive program of observations of stratospheric chlorine monoxide and also for observations of other stratospheric trace gases such as (O-16)3, vibrationally excited (O-16)3, (O-18)2(O-16), N2O, HO2, and HCN. In the present paper, analysis of the observing technique is given, including the method of calibration and analysis of sources of error. The technique is found to be a reliable means of observing and monitoring important stratospheric trace constituents.
    Keywords: GEOPHYSICS
    Type: Radio Science (ISSN 0048-6604); 23; 106-118
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  • 3
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    Formation of the Antarctic ozone hole by the ClO dimer mechanism (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New measurements of the low-altitude ClO profile, made during September 1987, are presented along with detailed observations of ozone depletion over McMurdo Station, Antarctica during the same period. The results show that both the rate and altitude range of ozone depletion can be quantitatively accounted for by a mechanism in which the ClO dimer is the important intermediary in the catalytic destruction of ozone. An alternative bromine mechanism appears capable of contributing only 5-15 percent to the ozone loss rate.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 336; 455-458
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  • 4
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    A quasi-continuous record of atmospheric opacity at lambda = 1.1 mm over 34 days at Mauna Kea Observatory (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A quasi-continuous record of atmospheric attenuation is obtained. The data were gathered during a 24-day period in September and October 1982 and a 10-day period in December of that year. The opacity is arrived at by measuring the thermal emission of the atmosphere over a bandwidth of approximately 300 MHz. Using an experimental relationship established by Zammit and Ade (1981), opacity measurements at 1.1 mm are converted to the precipitable water vapor column overhead. With the precipitable water vapor, estimates of opacity due to water vapor can be made for other mm and FIR wavelengths. These estimates require model absorption curves for the atmosphere.
    Keywords: GEOPHYSICS
    Type: International Journal of Infrared and Millimeter Waves (ISSN 0195-9271); 4; Sept
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  • 5
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    Chlorine oxide in the stratospheric ozone layer Ground-based detection and measurement (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Stratospheric chlorine oxide, a significant intermediate product in the catalytic destruction of ozone by atomic chlorine, has been detected and measured by a ground-based 204 GHz, millimeter-wave receiver. Data taken at latitude 42 deg N on 17 days between January 10 and February 18, 1980 yield an average chlorine oxide column density of approximately 1.05 x 10 to the 14th/sq cm or approximately 2/3 that of the average of eight in situ balloon flight measurements (excluding the anomalously high data of July 14, 1977) made over the past four years at 32 deg N. Less chlorine oxide below 35 km and a larger vertical gradient than predicted by theoretical models of the stratospheric ozone layer are found.
    Keywords: GEOPHYSICS
    Type: Science; 211; Mar. 13
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  • 6
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    A measurement of stratospheric HO2 by ground-based millimeter-wave spectroscopy (1984)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Stratospheric perhydroxyl (HO2) was measured by using a sensitive mm-wave receiver to obtain spectroscopic line profiles of three rotational emission lines in the vicinity of 265.8 GHz. The observations were carried out over four days in September-October 1982 at Mauna Kea, Hawaii and yield good agreement with the column density and vertical distribution predicted above 35 km by three representative two-dimensional photochemical models employing JPL 82-57 reaction rates and chemistry. Contrasts between current theoretical predictions and previous observations by Anderson et al. (1981) are pointed out for HO2 in the 28 to 37-km range, along with the difficulty of joining the latter with the present measurements through a monotonically varying vertical profile for HO2. A possible explanation involving strong temporal and spatial variation in stratospheric water vapor content is suggested.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 1321-132
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  • 7
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    New observations of a large concentration of ClO in the springtime lower stratosphere over Antarctica and its implications for ozone-depleting chemistry (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: New measurements of stratospheric chlorine monoxide (ClO) were made at McMurdo Station, Antarctica, during the austral spring of 1987. Rotational emission line spectroscopy, employing a ground-based detector, was used to determine mixing ratio profiles over the range about 17-45 km. A spectral band pass double that was used for similar measurements in 1986 allowed an improvement to be made in the definition of the anomalous low-altitude stratospheric ClO layer associated with springtime ozone depletion. A peak mixing ratio of 1.6 + or - 0.4 parts per billion by volume (ppbv) (95 percent confidence level) was found at 19.5 + or - 1 km at midday during the period September 20-24, 1987. The observed peak mixing ratio and diurnal behavior are discussed in relation to chemical depletion theories. Calculations indicate that the large observed ClO concentration provides an efficient closure for a catalytic Cl cycle through the ClO dimer mechanism, yielding good agreement with various observed features of O3 depletion.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 11423-11
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  • 8
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    Measurements of stratospheric hydrogen cyanide at McMurdo Station, Antarctica - Further evidence of winter stratospheric subsidence? (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Measurements of hydrogen cyanide in the springtime Antarctic stratosphere were made using ground-based millimeter wave spectroscopy. A steeper decrease in volume mixing ratio with altitude was found, than that found at tropical latitudes, from an assumed value of about 160 pptv in the troposphere to a value of 65 + or - 30 pptv at 40 km, which may be further evidence of substantial vertical subsidence of the Antarctic winter stratosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 16773-16
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  • 9
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    Ozone over McMurdo Station, Antarctica, austral spring 1986 - Altitude profiles for the middle and upper stratosphere (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: In the austral spring of 1986, a program of measurements of the ozone altitude profile (for the z values between 25 and 55 km), relevant to an understanding of the ozone hole, was conducted at McMurdo Station, Antarctica. The measurements were performed using ground-based millimeter-wave spectrometry. It was found that the ozone mixing ratio peaked at altitudes ranging from 28 to 34 km, with peak values between 5 and 9 ppm by volume. During the period between September 12 and October 29, the ozone mixing ratio decreased, with great variability, by about 15 percent at 25 km, with no significant decrease at higher altitudes. The observation of the depletion occurring only below 25 km is consistent with ozone-sonde observations during previous years.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 13221-13
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  • 10
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    Nitrous oxide in the tropical middle atmosphere, observed by ground-based mm-wave spectrometry (1987)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Measurements of stratospheric N2O were made from Mauna Kea in Hawaii in June 1983, and in May and June 1986, by observing thermal emission of the molecule in a rotational transition at about 1 mm wavelength. Analyses of the data yield altitude profiles in the middle and upper stratosphere. Useful measurements of N2O may be made in one to two hours. The N2O profiles agree reasonably well with model predictions and with published satellite data, though significantly more N2O is reported near the stratopause than shown by the satellite measurement, and significantly more N2O in the middle stratosphere than in one of the models. The discrepancy between these data and the satellite measurement may be due in part to variations induced by the solar cycle.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 14; 1254-125
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