Vertical Ozone Research Articles

Simulation ozone model in the middle atmosphere of the Northern Midlatitudes

All available radiance measurements collected from satellite experiments to measure ozone since 1978 are used to simulate vertical ozone structure in the middle atmosphere at middle latitudes of the northern hemisphere. This simulation is made for each month of the year separately, and for the latitudes 30°N, 40°N and 50°N, extending from 20hPa to 0.03hPa pressure levels. The intermidiate pressure levels we have used are twenty six. Equations giving the zonal mean ozone volume mixing rations as a function of both height and time are also presented.

Differential absorption lidar measurement of vertical ozone profiles in the troposphere that contains aerosol layers with strong backscattering gradients: a simplified version

A technique for determining approximate ozone-concentration profiles from differential absorption lidar (DIAL) data obtained in the troposphere with large gradients of aerosol backscattering is presented. The atmospheric interferences are defined as errors of the off-on DIAL signal ratio; the interferences are separated and removed before the ratio is differentiated. To facilitate the separation of the regular (subjected to differentiation) component of the signal ratio from random noise, the ratio is transformed into an intermediate function, and the measurement error is minimized by fitting of an analytical function to the transformed function. Simple criteria are used to demarcate atmospheric layering, for which a strong aerosol-backscattering gradient can result in an unacceptably large error in the measured ozone concentration.

Intercomparison campaign of vertical ozone profiles including electrochemical sondes of ECC and Brewer-Mast type and a ground based UV-differential absorption lidar

An intercomparison campaign was conducted at the Observatoire de Haute Provence (OHP) in Southern France in September 1989 in order to compare the three instruments used for vertical tropospheric ozone profiling in the European TOR (Tropospheric Ozone Research Project) network: balloon borne ECC and Brewer-Mast sondes and a ground based UV-DIAL (DifferentialAbsorptionLidar). Additionally, a stratospheric lidar system and the Dobson spectrophotometer of the OHP were operated. Seven simultaneously measured vertical ozone profiles gave evidence for systematic differences of 15% between both types of electrochemical sondes in the troposphere, the Brewer-Mast sondes reading the smaller ozone values. These differences might be explained on the one hand by a possible contamination of the ozone sensor with reducing substances, causing a negative bias mainly for Brewer-Mast sondes and, on the other hand, by the evolution of the sonde background current during the flight, causing a positive bias for ECC sondes and a negative bias for Brewer-Mast sondes. The tropospheric lidar system, measuring the vertical ozone distribution between 6 and 12–15 km, showed ozone concentrations intermediate between the sonde results. This is in good agreement with its estimated systematic error of better than 7% in the upper troposphere. In the stratosphere, the differences between electrochemical sondes and the lidar are between 5 and 10% before the normalisation with the total ozone values measured by the Dobson spectrophotometer, and always below 5% after. While the Dobson normalisation thus corrects rather well the stratospheric part of the sonde profile, it only partially reduces errors occurring in the troposphere.

Ozone depletion in the Arctic stratosphere in early 1993

During the first three months of 1993 measurements of the vertical ozone profile, with balloon‐borne sensors, were performed in Greenland. A substantial ozone depletion took place from the end of January to the end of March in the altitude range between approximately 14 and 20 km. An ozone decrease of about 1% per day is ascribed to chemical destruction inside the polar vortex based on air parcel trajectory analysis, using measurements of lower stratospheric aerosols as dynamical tracers to correct for diabatic subsidence. The column‐integrated total ozone loss was found to be about 48 Dobson units or 12%. These measurements are in good agreement with satellite observations, and further document the 1993 springtime stratospheric ozone depletion as the most severe and long lasting yet reported for the Arctic.

Climatology of tropospheric ozone in southern Europe and its relation to potential vorticity

A climatology of the vertical ozone distribution in the troposphere is obtained by balloon‐borne Brewer‐Mast sondes at the Observatoire de Haute Provence (OHP), southern France (44°N, 6°E, 700 m above sea level), during the period 1984 to 1990. The tropospheric ozone seasonal variation is characterized by a large maximum in spring and summer. A comparison to other ozone sounding stations gives evidence for a meridional ozone gradient in the middle and upper troposphere in Western Europe, with larger ozone values at Uccle (51°N, 4°E) and Jülich (50°N, 6°E) than at the OHP (44°N, 6°E.). A statistical analysis of ozone concentrations together with potential vorticity, a tracer of stratospheric air masses, shows a partial but significant correlation between both variables (r = 0.40, significance > 99.9%), implying a noticeable impact of stratosphere‐troposphere exchange on the ozone variability. Concerning the spring/summer maximum of tropospheric ozone, it is shown to be caused both by ozone transfer from the stratosphere and by in situ photochemical ozone production. A climatology of the ozone/potential vorticity ratio is established for the OHP and its altitude and seasonal dependence is given. Finally, it is shown that the interannual variability of potential vorticity can cause dynamically induced trends of the ozone concentrations, which have to be taken into account to determine accurately the relative part due to human activity.

Association of the Laminated Vertical Ozone Structure with the Lower-Stratospheric Circulation

In this study the examination of the role of the atmospheric circulation in the lower stratosphere in relation to the laminated structure of ozone in the subtropical atmosphere is attempted. This analysis is based on the vertical ozone profile data collected by balloon-borne sondes released at Athens, Greece (38°N, 24°E). From the 29 ozone soundings performed during the winter 1991/92 in the framework of both the European Arctic Stratospheric Ozone Experiment (EASOE) and the Tropospheric Ozone Research (TOR), it is shown that the lamination phenomenon in ozone profiles, especially in the lower stratosphere, was very frequently present. Furthermore, a characteristic minimum of ozone partial pressure at the height region of 14–17 km has also been detected. The occurrence of the laminated ozone structure as well as the appearance of the characteristic ozone minimum, correlated with the general circulation, leads to the following results: (a) The laminated ozone profiles are associated with the north-northwest circulation in the lower stratosphere; and (b) the characteristic ozone minimum is related to the influence of the subtropical jet stream circulation.

Quasi-Biennial Oscillations of Ozone and Diabatic Circulation in the Equatorial Stratosphere

The quasi-biennial oscillation (QBO) in ozone in the equatorial stratosphere is obtained by analyzing the Stratospheric Aerosol and Gas Experiment (SAGE) data from 1984 to 1989. The phase of the ozone QBO in the lower stratosphere is found to precede the zonal wind QBO by several months as opposed to the theoretically expected in-phase relationship between the two. A mechanistic model is developed to explore possible reasons for this disagreement. The model is capable of simulating the actual time evolution of the ozone QBO by introducing the observed zonal wind profile as input. The modeled results confirm the conventional view that the ozone QBO is generated by the vertical ozone advection that is driven to maintain the temperature structure against radiative damping. However, a series of experiments emphasizes the importance of the feedback of the ozone QBO to the diabatic heating through the absorption of solar radiation. Due to this effect, the phase of the ozone QBO shifts up to a quarter cycle ahead and approaches that of the temperature QBO. Because of this inphase relationship, the feedback of the ozone QBO to the diabatic heating acts to compensate for the radiative damping of the temperature structure, thus reducing the magnitude of the induced diabatic circulation. Because the reduction of the magnitude of the vertical motion facilitates downward transport of easterly momentum by the mean flow, this feedback process can help to resolve the insufficiency of the easterly momentum in driving the dynamical QBO in general circulation models (GCMs). It should be emphasized that more sophisticated models that allow for full interaction between the chemical species and radiative and dynamical processes should be developed to improve our understanding of both dynamical and ozone QBOs.

Comparison of vertical ozone profiles as deduced from remote and in situ sensing techniques

Abstract A number of vertical ozone profiles up to 35 km in height, have been measured using balloon-based sensors at Athens, Greece (38° N, 24° E). The measurements were made during the winter of 1991-1992, as part of the European Arctic Stratospheric Ozone Experiment (EASOE). The data collected during the balloon ascents have been compared with those during the balloon descents. Both profiles are compared with the total ozone measurements derived from the TOMS on the Nimbus-7 satellite and the Dobson spectrophotometer.

UVB radiation changes in Berlin between 1967 and 1990 following alterations in the ozone layering

Long-term measurements covering the past 24 yr in the vicinity of the city of Berlin have shown that ozone has increased in the troposphere and in the middle stratosphere and has decreased in the lower stratosphere. The total ozone column amount, however, has remained constant. Possible changes of the UV irradiance [280 nm ⩽ λ ⩽ 320 nm (UVB)], due to this observed vertical ozone redistribution, have been calculated. The analysis reveals an UVB irradiance increase at those times of each year where maximum ozone concentrations have occurred as well as during summer times. On the contrary, UVB has remained unchanged whenever ozone concentrations were minimal. In any case, however, the UVB irradiance oscillates with the sunspot cycle of ~ 11 yr period with an amplitude ⪝1%.

Some features of the vertical ozone distribution from millimeter wave measurements at Pushchino and Onsala observatories

A number of features of the stratospheric ozone distribution were revealed by joint millimeterwave observations of ozone emission lines at 142,175 and 110,836 GHz carried out during the winter periods of 1988–1989 and 1989–1990 at the Radioastronomical Observatory of the P.N. Lebedev Physical Institute of the Russian Academy of Sciences and at the Onsala Space Observatory of Chalmers University of Technology, Sweden. It is shown that vertical ozone variations observed at the two observatories were connected with large scale dynamical processes that occurred in the stratosphere. When the stratosphere was relatively undisturbed the ozone profiles obtained at both observatories were close to the ozone reference model given by Keating and Pitts. There were periods during a stratospheric warming when the ozone content measured at the two observatories in the 25–40 km altitude range was higher by a factor ~ 1.5 than the model values. Dynamical processes in the stratosphere also gave rise to rapid (4 h duration) and large deviations from the model ozone profile. An ozone layer depletion was observed in the 27–55 km altitude range. The observed ozone variations illustrate the sensitivity of the ozone distribution to stratospheric disturbances including stratospheric warmings.

Atmospheric ozone concentration at Athens, Greece. Part II: Vertical ozone distribution in the trophosphere

In the framework of the European Arctic Stratosperic Ozone Experiment (EASOE) and the Tropospheric Ozone Research (TOR) programme we have performed twenty ozone soundings over Athens, Greece (37.9°N, 23.8°E) during the period from December 1991 to March 1992. The intercomparison of Athens tropospheric mean values with the corresponding values which have been measured at Julich, Germany (50.6°N, 6.2°E) two years ago, shows that in the height region of 1–4 km Athens values are about 20% higher. Also, the same intercomparison in the height region 4–8 km shows that Athens values are about 10% higher than those obtained in Julich. Finally, the examination of the transport occured at 700 hPa level showed that with advection from the north-western sector the ozone mean value was 50.9 ± 3.8 ppb, while 46.9 ± 2.1 ppb with advection from the south-southwestern direction.

Vertical ozone variation in the lower troposphere of Delhi

Measurements of ozone in the urban environment of Delhi were carried out at ground level and heights of 23m, 51m, 117m and 153m at four different sites synoptically during 1989-90. A considerable ozone build up was observed all over Delhi and a significant vertical variation in its concentration was observed at all sites. At any given time O3 levels were lowest at ground level and invariably increased with increasing distance from the ground.

Evidence for vertical ozone redistribution since 1967

Long-term measurements of the ozone concentration in the vicinity of the city of Berlin have been performed with ground based Dobson spectrophotometers and balloon borne systems. The respective experiments cover the past 24 years. All data have been reevaluated and corrected towards uniform calibration standards, leading to the longest European data set of total column density, altitude-dependent ozone partial pressures and the corresponding temperatures. Smoothing algorithms unravel significant long-term trends. The analysis shows an increase of ozone concentration within the middle stratosphere (below 31 km height) as well as in the troposphere over the past 24 years. On the contrary, ongoing ozone depletion in the lower stratosphere has been found. The large scale vertical redistribution of atmospheric ozone in the troposphere and the lower stratosphere seems to be in agreement with model calculations and trend predictions that have their roots in changes of the chemical composition and the ozone photochemistry due to anthropogenically induced trace gas concentrations.

On the relationships between vertical ozone distribution and middle atmosphere dynamics during stratospheric warming at solar minimum

On the basis of a statistical analysis synonymous relationships between ozone concentration and wind and temperature — the main atmospheric parameters characterizing warming, are established. The investigations were carried out over Southeastern Europe during the solar minimum. Use was made of the most important levels in the maximum of the ozonosphere, reflecting the photochemistry and accumulation of this constituent in the atmosphere.

Stratospheric ozone profiles based on the EXOS-C satellite data

Monthly and zonal average distributions of ozone in a meridional plane were obtained using the UV spectrometer data on the EXOS-C satellite during March 1984 – September 1987. Individual vertical ozone profiles retrieved from the measured spectral intensities of the backscattered UV was proved to be in general agreement within ±10% with those from ground-based measurements. The EXOS-C meridional ozone distributions are constracted and compared with those of the CIRA model to exhibit an agreement within ±10% on the average in the atmospheric pressure range of 15 – 1.5 mb (altitudes between ∼28 km and ∼45 km). At altitudes above ∼50 km, the EXOS-C ozone volume mixing ratios are systematically smaller than those of the CIRA. This difference can be attributed to a calibration bias. Amplitudes of seasonal variations in ozone volume mixing ratios are also obtained at various latitudes and atmospheric pressure levels and compared with those of the CIRA.

Evidence for vertical ozone redistribution since 1967

Long-term measurements of ozone concentration in the vicinity of the city of Berlin have been performed with ground-based Dobson spectrophotometers and balloon borne systems. The respective experiments cover the past 24 yr. All data have been re-evaluated and corrected towards uniform calibration standards, leading to the longest lasting European data set of total column density, altitude-dependent ozone partial pressures and the corresponding temperatures. Smoothing algorithms reveal significant longterm trends. The analysis shows an increase of ozone concentration within the middle stratosphere (below 31 km height) as well as in the troposphere over the past 24 yr. On the contrary, ongoing ozone depletion in the lower stratosphere became evident. The large scale vertical redistribution of atmospheric ozone in the troposphere and the lower stratosphere seems to be in agreement with model calculations and trend predictions that have their roots in changes of the chemical composition and the ozone photochemistry due to anthropogenically induced tracer gas concentrations.

Airborne Lidar Mapping of Ozone Concentrations During the Lake Michigan Ozone Study

An airborne differential absorption lidar (DIAL) was used during the 1991 Lake Michigan Ozone Study (LMOS) to map the vertical distribution of ozone concentrations across Lake Michigan downwind of urban and industrial areas of the south lake region. The DIAL, which was designed as a compact instrument for installation on relatively small-sized twin-engine aircraft typically used on regional air quality studies, is based on an excimer laser and Raman cell to generate multiple-wavelength ultraviolet energy appropriate for remote measurement of tropospheric ozone. Collected DIAL data are displayed in terms of contour analyses of vertical ozone concentration distributions across Lake Michigan. During times of southwesterly winds, large-scale urban ozone plumes were observed (mostly over the lake and eastern shoreline) that increased in concentration during the day. Small-scale elevated ozone minima, caused by subsidence of clean air aloft and by chemical destruction of ozone by industrial reactive-gas plumes ...

Annual and semiannual waves in ozone as derived from SBUV vertical global ozone profiles

Global averages of monthly ozone profile data obtained using the solar backscatter ultraviolet (SBUV) instrument, are analyzed for the period from November 1978 to September 1985. Differences between ozone profile data for Umkehr layers 4 to 10 ‐ from 19 km to 53 km, approximately ‐ and the deseasonalized ozone data are first estimated for the entire time period at all Umkehr layers, and are then Fourier analyzed to obtain the amplitude, phase and percentage contribution to the total variance of the first and second harmonics. It is found that the annual wave in global ozone is strong in the high and low stratosphere and weak in the middle stratosphere, whereas the semiannual wave in global ozone is strong in the middle stratosphere. Global ozone deviations at Umkehr layer 7 are compared to the 10.7 cm solar flux to yield a strong positive correlation for the entire period, which implies that the quasi‐semiannual wave in global ozone depends on the quasi‐semiannual wave of the 10.7 cm solar flux.

Results of the new and old Umkehr algorithm compared with ozone soundings

Vertical ozone distributions from regular Umkehr observations at Arosa, Switzerland, from 1956 to 1990 retrieved with the newly developed algorithm of mateer and Deluisi (1992, J. atmos. terr. Phys. 54, 537), using Bass-Paur absorption coefficients and described in this issue, are compared with the corresponding results obtained with the old routine [ Mateer and Duetsch (1964), NCAR, Boulder, Colorado, Part I, 105 pp.], officially in use at the World Ozone Data Center at Toronto. For the period 1967–1989 they are also compared with the sounding data obtained at Payerne, Switzerland with the Brewer-Mast electrochemical instrument. The annual mean values calculated from Umkehr observations increased, using the new algorithm, in layer 4 and to a lesser extent in layers 3 and 1. They decreased strongly in layer 2 and also 6 and became smaller, too, in layers 7 and 8. The new Umkehr yields annual mean values which are much closer to the sounding results than those of the old routine. The seasonal variation shows somewhat larger differences. There are big discrepancies between the trends obtained from both Umkehr algorithms and those calculated from the soundings in the region of the ozone maximum and in the troposphere. The former discrepancies may be due to the changes in the relation between total ozone and vertical distribution which occurred during the past 20 years and which are not taken into account in the definition of the a priori profiles in the new routine. It seems that useful trends can only be obtained in layer 6 and above using Umkehr observations.

Long-term tropospheric and lower stratospheric ozone variations from ozonesonde observations

An analysis is presented of the long-term mean pressure latitude seasonal distribution of tropospheric and lower stratospheric ozone for the four seasons covering, in part, over 20 years of ozonesonde data. The observed patterns show minimum ozone mixing ratios in the equatorial and tropical troposphere except in regions where net photochemical production is dominant. In the middle and upper troposphere, and low stratosphere to 50 mb, ozone increases from the tropics to subpolar latitudes of both hemispheres. In mid stratosphere, the ozone mixing ratio is a maximum over the tropics. The observed vertical ozone gradient is small in the troposphere but increases rapidly above the tropopause. The seasonal variation at a typical mid latitude station (Hohenpeissenberg) shows a summer maximum in the low to middle troposphere, shifting to a winter-spring maximum in the upper troposphere and lower stratosphere and spring -summer maximum at 10 mb. The amplitude of the annual variation increases from a minimum in the tropics to a maximum in polar regions. Also, the amplitude increases with height at all latitudes up to about 30 mb where the phase of the annual variation changes abruptly. The phase of the annual variation is during spring in the boundary layer, summer in mid troposphere, and spring in the upper troposphere and lower stratosphere. The annual long-term ozone trends are significantly positive at about + 1.2% yr in mid troposphere (500 mb) and significantly negative at about − 0.6% yr 1 in the lower stratosphere(50mb)