A measurement of the ozone concentration from 65 to 75 km at night

The concentration of ozone between 65 and 75 km has been determined from measurements of the attenuation of moonlight at 2570 Å made from a Moon-pointing rocket payload. The results support earlier rocket measurements, but are in marked disagreement with some recent data obtained by Hays and Roble using the stellar occultation technique.     

NASA-JSC measurements during “la campagne d'intercomparaison d'ozonometres”, Gap,France, June 1981

Measurements made by the NASA-JSC ozone instrument during the ozone intercomparison campaign from Gap, France during June 1981 are reported. Two flights were made on board the large balloon platform with other instruments using different techniques. The NASA-JSC instrument employs u.v. absorption photometry to obtain in situ results. Concentration (molecules cm^?3) and mixing ratio (pp mV) profiles are given for altitudes from 16 km to float altitudes of 32 and 39 km, respectively for the two flights. A measure of the total column content of ozone was obtained by integrating the NASA-JSC results from 16 km to float altitude and combining them with results from other techniques below 16 km and above float altitudes. Comparisons with results from other instruments are reported elsewhere in this publication.     

Measurement of the vertical ozone distribution by means of an in situ gas phase chemiluminescence ozonometer during the intercomparison ozone campaign,Gap, France,June 1981

Two vertical ozone profiles have been obtained above Gap (France), with an instrument using a gas phase chemiluminescence technique. Data are given for each 0.5 km. The absolute uncertainty on the measurements increase with altitude from 8% of mixing ratio at 16 km to, at most, 15% at 38 km. Uncertainty analysis leads to an incompressible 6%. The integrated column content between 16 km and flight ceiling is also given.     

Ionosphere disturbances accompanying the flight of the Chelyabinsk body

Data received from a network of ionosondes located at distances of 1500–3100 km from the Chelyabinsk meteorite site are used to analyze ionospheric disturbances at a height of approximately 300 km following the flight and explosion of the space body. The fall of the meteoroid is believed to be accompanied by the generation of gravitational waves in the neutral atmosphere and traveling ionospheric disturbances. The velocity and period of the latter are 600–700 m/s and 70–135 min, respectively; the amplitude of relative electron concentration disturbances is 10–20%. There is evidence of the 6–7 h ionospheric presence of wave electron concentration disturbances with relative amplitude of 10–20%, which could have been caused by long-living whirlwinds in the upper atmosphere.     

Ozone determinations by lunar rocket photometry

Atmospheric ozone number densities have been determined over the altitude range 30–75 km by measuring the absorption of lunar u.v. radiation in a number of wavelength bands between 2400 Å and 2900 Å. The measurements were made from rockets fired at night at times close to full Moon and show significant variations in ozone densities particularly at the higher altitudes. Comparison with other observations indicates that above 60 km the ozone densities at night are markedly greater than they are during the day.     

The measurement of ozone concentrations at high latitude during the twilight

The ozone height profile in the Arctic, at the end of the winter, has been measured up to an altitude of 100 km using a combined solar occultation and 1.27 μ oxygen emission technique. The typical two layer structure has been observed with a high altitude minimum near 80 km and a maximum at 86 km. The measured concentration in this ozone bulge was 5.1 × 10⁷cm^?3, typical of that measured at 52°N for the summer months. It is suggested that this reduced ozone concentration may have been associated with a stratospheric warming event that was in progress at the time of the measurement.     

GSFC optical ozonesonde results during the Gap,France, intercomparisons,June 1981

A GSFC Super Loki optical ozonesonde instrument was flown as part of the ozone sensor intercomparison balloon campaign at Gap, France, in June 1981. A primary objective was to confirm biases between external absorption techniques, such as the GSFC sonde, and in situ techniques, which include ECC, Mast-Brewer, and DASIBI sondes. Ozone distributions were obtained with the GSFC sonde on three of the four ascent-descent legs of the first flight on 19 June. Ozone densities were measured redundantly over altitudes from 22 to 32 km using filters centered at 303 and 300 nm. The three profiles obtained by averaging the data from the two channels are in close agreement with an average S.E. of 1.4%. However, small but consistent differences were found between the ozone densities measured at the two wavelengths. The average difference is 5% using Vigroux cross sections and 4% using preliminary Bass cross sections. The integral ozone amount above the first ceiling altitude of 32.85 km was determined by the Langley plot method to be 45 D.U. The total ozone derived by integrating the optical ozonesonde and ECC profiles is within 2% of the Chiran Dobson Spectrophotometer observation based on a pre-campaign calibration but is 9% greater than the amount derived using a post-campaign calibration.     

A global study of O2(1Δg) airglow: Day and twilight

Aircraft measurements of $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ emission made over a 10-yr period provide information on the variation of ozone with latitude and season in the altitude region 50–90 km. Between 50 and 70 km there appears to be little variation (< ± 25%) whereas the abundance between 80 and 90 km exhibits a large seasonal change north of 30°N and much less at lower latitude. At mid and high latitude the column abundance above ～ 80 km changes from ? 1 × 10¹⁴ cm^?2 in summer to about 3 × 10¹⁴ cm^?2 in winter. There are occasional enhancements in both the day and twilight airglow which almost always occur in association with auroral activity or, at least, where such activity is statistically most likely. These enhancements appear to reflect a corresponding increase in the ozone mixing ratio in the upper stratosphere. While the gradient in ozone mixing ratio with latitude is generally small at altitudes between 50 and 90km there are occasions when a temporary latitude structure can be seen, particularly above 80 km.     

Three-dimensional simulations of ozone in the stratosphere and comparison with UARS data

A 3-D Atmospheric Chemical Transport model has been developed and used to simulate the present-day ozone distributions in the troposphere and stratosphere. A 5-year-long steady-state model run using 1995 boundary conditions and circulation fields derived from the 24-layer University of Illinois at Urban a-Champaign (UIUC) Atmospheric General Circulation model has been carried out. The simulated distribution of ozone is compared with available observations made by the HALOE, CLAES and MLS instruments onboard the LIARS satellite. The comparison is carried out for the monthly zonal-mean climatology of the ozone distribution. The correlations between the monthly zonal-mean ozone derived from the simulated and measured data are calculated. The results of this comparison show reasonable agreement (within 30%) of the simulated and measured monthly zonal-mean ozone distributions, although the location of the simulated maximum in the ozone distribution is generally lower by about 2–3 km than shown by the satellite data. The model overestimates the ozone mixing ratio in the lower stratosphere and slightly underestimates it in the upper stratosphere. A better overall agreement was found between the simulated ozone and the ozone measured by HALOE than by CLAES and MLS.     

Measurements of the ozone vertical distribution (0–25 km): Comparison of various instruments,Gap—Observatoire de Haute-Provence June 1981

A tentative comparison is made between the various instruments operated at Gap and at the Observatoire de Haute-Provence to measure the ozone vertical distribution up to 25 km during the Intercomparison Ozone Campaign. This includes comparison of the three ozonosondes carried on the same payload during the stratospheric open air balloon flights on 19 June and 25/26 June 1981, comparison between Brewer Mast sondes and electrochemical concentration cells on 19 and 26 June. A specific comparison has been made between a ground-based lidar and ECC sondes launched at the same location on 20/21 June 1981. Also compared are the ozone distributions as monitored between 12 June and 20 June 1981 by two ground-based instruments : lidar (active sounding) or Dobson spectrometer using the Umkehr method. Analysis of the various data set are performed in terms of relative variations observed and potential causes of discrepancies.     

An overview of sage I and II ozone measurements

The Stratospheric Aerosol and Gas Experiments (SAGE) I and II measure Mie, Rayleigh, and gaseous extinction profiles using the solar occultation technique. These global measurements yield ozone profiles with a vertical resolution of 1 km which have been routinely obtained for the periods from February 1979 to November 1981 (SAGE I) and October 1984 to the present (SAGE II). The long-term periodic behavior of the measured ozone is presented as well as case studies of the observed short-term spatial and temporal variability.

A linear regression shows annual, semi-annual, and quasi-biennial oscillation (QBO) features at various altitudes and latitudes which, in general, agree with past work. Also, ozone, aerosol, and water vapor data are described for the Antarctic springtime showing large variation relative to the vortex. Cross-sections in latitude and altitude and polar plots at various altitudes clearly delineate the ozone hole vertically and areally. Comparisons of vertical profiles are made from 1979 to 1988.

Although there is a three-year gap between the SAGE I and II measurements, the two data sets have been used to determine long-term changes in ozone. The intercomparison generally shows decreases in the upper stratosphere (25–50 km) of 4% or less from 1980 to 1986.     

Rocket observations of the interaction of auroral electrons with the atmosphere

Electron spectra obtained during the flight of Black Brant VB-31 on August 17, 1970 through a stable aurora to a height of 268 km have been analyzed in detail to obtain the pitch angle distributions from 25 to 155° and the electron energy distributions over an energy range of 18 keV to 20 eV through the region of atmospheric interaction down to 97 km. Backscatter ratios for 140° pitch angle range from 0.065 for 18 keV electrons to 0.22 for 1 keV electrons. Backscatter of lower energy electrons decreases with atmospheric depth below 200 km. The effect of the interactions between auroral electrons and the atmosphere is such as to give a peak in electron flux which moves progressively to higher energies with penetration depth. The secondary electron flux increases monotonically with height up to 200 km. The secondary electron spectrum can be approximated by an energy power over small energy ranges but its form is somewhat dependent on height and on the primary electron spectrum.     

1302Å absorption measurement of atomic oxygen concentrations in the high latitude winter upper atmosphere

The first measurement of atomic oxygen concentration in the upper atmosphere using the resonance absorption lamp method was made 23 January 1974 in a flight from the Churchill Research Range (58.4°N, 94.1°W, geographic) in northern Canada. Earlier difficulties with the data analysis have been resolved to a limited extent, and a concentration profile over the range 90–155 km is presented here. In the interim period, the same technique has been employed by a number of investigators, but the importance of the present data is that the atomic oxygen concentration was measured by three independent methods on the same flight, aeronomical and mass spectrometric methods being used as well as resonance absorption. The results are in good agreement when current aeronomical understanding is employed. Comparison is made with other measurements and it is concluded that the high degree of variability observed may well be real. A simple argument based on these data shows that O₂(c¹Σ) cannot be the sole source of O(¹S) and O₂(b¹Σ) in the aurora.     

On the influence of the aerosols for satellite measurements of ozone at the thermospheric base

The dust layer at an altitude of about 80 km causes the attenuation of the light of the stars during the OAO-2 satellite observations near the horizon. This is compared with absorption due to ozone near to 2400 A in the spectral range, using ozone concentration measured by the OAO-2 satellite.     

On the role of the lower-stratospheric circulation to the vertical ozone structure

The examination of the role of the lower stratospheric circulation to the vertical ozone distribution, is attempted by using the vertical ozone profiles collected by balloon-borne sondes released at Athens, Greece (38°N, 24°E), throughout the period 1989–1997. The most pronounced special features of the ozone structure, such as lamination phenomenon, minimum of ozone partial pressure at the height region of 14–17 km and ozone minima at the height region of 20–25 km, have been used in order to create groups of relevant profiles. The occurrence of the above mentioned features, correlated with the circulation pattern, leads to the following preliminary results: a) Laminated features are associated with the north-northwest circulation in the lower stratosphere; b) The lower stratosphere's characteristic ozone minimum is related to the influence of the subtropical jet stream circulation; and c) The observed ozone depletion at the height region of 20–25 km, is characterized by the movement of the polar vortex to the mid-latitudes, resulting more intense north-western circulation above our experimental site.     

A theoretical model of distribution of atmospheric ozone with altitude

A critical study of distribution of ozone with altitude of about 91 Km and above has been made and following important results are obtained:(i) An empirical equation is fitted theoretically between the variation of ozone concentration and altitude at a definite time.(ii) The rate of change of O₃ concentration with respect to altitude is directly proportional to the O₃ concentration at that altitude.(iii) From analysis it is shown that ozone concentration decreases with the increase of altitude.     

Ozone profile intercomparison based on simultaneous observations between 20 and 40 km

The vertical distribution of stratospheric ozone has been simultaneously measured by means of five different instruments carried on the same balloon payload. The launches were performed from Gap during the intercomparison campaign conducted in June 1981 in southern France. Data obtained between altitudes of 20 and 40 km are compared and discussed. Vertical profiles deduced from Electrochemical Concentration Cell sondes launched from the same location by small balloons and from short Umkehr measurements made at Mt Chiran (France) are also included in this comparison. Systematic differences of the order of 20% between ozone profiles deduced from solar u.v. absorption and in situ techniques are found.     

Ozone and photochemistry of the Martian lower atmosphere

The calculation of number densities of CO₂, H₂O and N₂ photolysis products was carried out for the Martian atmosphere at heights up to 60 km. The ozone distributed in the atmosphere as a layer of 10 km width with [O₃] max = 2.5 × 10⁹ cm³ at height of 35 km which agree well with the results of u.v. observations on the evening terminator from the Mars-5 satellite. The calculated densities of O₂, CO and H₂O are also in good agreement with the measured data. The eddy diffusion coefficient is equal to 3 × 10⁶ in the troposphere (h ? 30 km) and 10⁸ cm² s^?1 above 40 km. The dependence of the total ozone content on water vapour amount in the atmosphere is considered; the hypothesis about the influence of water ice aerosol on the ozone formation is proposed to explain the high concentrations of ozone in the morning.     

Observation of mesospheric ozone at low latitudes

Stellar ultraviolet light near 2500 Å is attenuated in the Earth's upper atmosphere due to strong absorption in the Hartley continuum of ozone. The intensity of stars in the Hartley continuum region has been monitored by the University of Wisconsin stellar photometers aboard the OAO-2 satellite during occultation of the star by the Earth's atmosphere. These data have been used to determine the ozone number density profile at the occultation tangent point. The results of approximately 12 stellar occultations, obtained in low latitudes, are presented, giving the nighttime vertical number density profile of ozone in the 60- to 100-km region. The nighttime ozone number density has a bulge in its vertical profile with a peak of 1 to 2×10⁸ cm^?3 at approximately 83 km and a minimum near 75 km. The shape of the bulge in the ozone number density profile shows considerable variability with no apparent seasonal or solar cycle change. The ozone profiles obtained during a geomagnetic storm showed little variation at low latitudes.     

A theoretical model of atmospheric ozone depletion

A critical study on different ozone depletion and formation processes has been made and following important results are obtained:(i) From analysis it is shown that O₃ concentration will decrease very minutely with time for normal atmosphere when [O], [O₂] and UV-radiation remain constant. (ii) An empirical equation is established theoretically between the variation of ozone concentration and time. (iii) Special ozone depletion processes are responsible for the dramatic decrease of O₃-concentration at Antarctica.