Vertical Ozone Research Articles

A new Umkehr inversion algorithm

In this paper, we describe a new Umkehr algorithm for the estimation of the vertical ozone profile from observations of the umkehr effect of Götz. The algorithm uses new ozone absorption coefficients, which result in a change in the scale of measurement, and their temperature dependence. Better a priori ozone profiles are possible because of the very large increase in the archive of ozone profile measurements. The characterization of the retrieved ozone profiles and the error analysis follow the recipe of Rodgers. The differences between the new algorithm and the old 1964 algorithm are discussed. For both algorithms, only the retrievals for layers 4–8 (1943 km) are suitable for use in ozone trend analysis. For these layers, the retrieval resolution is trivially improved over that in the 1964 algorithm. For other layers, the retrievals either respond mainly to real ozone changes in adjacent or distant layers, or are a function of low-amplitude changes over a very broad range of layers. The effect of atmospheric aerosol on the retrieved profiles has been determined, and found to be generally similar to the effect for the old algorithm, but differing in some details.

Revision of 20 years of Dobson total ozone data at Uccle (Belgium): Fictitious Dobson total ozone trends induced by sulfur dioxide trends

Since July 1971, total ozone measurements have been performed at Uccle (50°48′N, 4°21′E) with the Dobson spectrophotometer 40. All the individual measurements were reevaluated after a careful homogenization, using the detailed calibration history of the instrument. Special care was taken to assure the consistency between direct Sun (DS) and zenith sky (ZS) measurements. The monthly mean values of percentage differences between the quasi‐simultaneous direct Sun and zenith sky measurements show a weak modulation, probably induced by long‐term changes in the mean vertical ozone distribution. The overall standard deviation of the percentage differences between the two types of observations amounts to 1.72%. From a detailed comparison of our revised data over the period 1971–1986 with the results of an approximate revision on a month‐by‐month basis (used in the Report of the International Ozone Trends Panel), it is concluded that the latter method of revision is not reliable. The trend of the reduced thickness of the SO2 amount in the lower troposphere, as measured with the Brewer instrument 16 located at the same site as the Dobson spectrophotometer, is in agreement with the trend of the SO2 density near the ground which has been measured in the urban area of Brussels since 1968. From these two SO2 data sets the variation of the reduced SO2 amount since 1968 and the corresponding correction of the Dobson instrument data of Uccle were calculated on a month‐by‐month basis. Without the SO2 correction the revised Dobson data for the period from August 1971 through July 1991 show a statistically significant downward trend (± standard deviation) that amounts to −1.38 ± 0.50% per decade, while after the SO2 correction a nonsignificant trend of 0.31 ± 0.51% per decade is found. This means that the decrease of SO2 over the last two decades at Uccle has induced a fictitious Dobson total ozone trend of −1.69% per decade. At the subperiod for which reprocessed total ozone mapping spectrometer (TOMS) data are available (November 1978 to May 1990) our corrected Dobson data show a statistically significant downward trend (± standard deviation) of −2.93 ± 1.17% per decade which is consistent with the results from TOMS; this proves that analysis of total ozone data over time periods as short as one solar cycle does not allow to make conclusive statements about long‐term trends. The spectacular decrease of SO2 densities is not a regional phenomenon but has been generally ascertained in European and North American urban areas; therefore it should not be neglected in any study about global ozone trends derived from Dobson data.

Vertical ozone profiles in a pine forest

Abstract Vertical profiles of ozone concentration have been measured in a pine forest located in the Landes region, in south-west France. In the daytime, ozone concentrations are nearly constant between ground level and an altitude of 35 m, the higher level of measurement. At night, important vertical variations of ozone concentration are observed in relation with temperature profiles. Analysis of the ozone profiles shows that the main ozone sink is the soil. When the ozone concentration near ground level is around zero, the ozone profile changes slowly, even in the main vegetation layer between 15 and 25 m height. This means that the chemical destruction of ozone at night is weak in comparison with its dry deposition at ground level.

NESDIS operational ozone data products

The NESDIS operational ozone monitoring program provides global ozone information obtained from a series of instrument/satellite systems. These include: • - The TIROS Operational Vertical Sounder (TOVS) on the TIROS-N satellite series from 1979 to present. • - The Solar Backscatter Ultraviolet radiometer (SBUV/2) on the NOAA-9 and -11 satellites from 1985 to present. The TOVS data product is the total ozone amount whereas the SBUV/2 products are total ozone amount and vertical ozone profiles. Characterization and validation of the data are being carried out by a joint NOAA/NASA contractor science team utilizing data from ground-based measurement systems as well as other satellite instruments. We present here the status of the observing systems and the data generated to date and a review of the results of some of the validation efforts.

Satellite ozone comparisons: Effects of pressure and temperature

We examine the direct effects of errors in determining temperature, pressure, and density in the background atmosphere on the comparison of ozone measurements by two different satellite sensors. Such comparisons, particularly between satellite instruments with different fundamental measurement techniques, provide an important method for checking the performance of these sensors. For example, ozone abundance profiles from the solar backscattered ultraviolet (SBUV) spectrometer on the Nimbus 7 satellite are being reanalyzed to remove the effects of long‐term instrument drift. Measurements from other ozone instruments are vital to this reanalysis; a primary comparison is that between SBUV observations and those from the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument on the Earth Radiation Budget satellite (ERBS). SAGE II observes ozone by solar occultation, giving values of ozone concentration versus geometric altitude. SBUV provides ozone overburden and its derivatives versus pressure. The conversion between geometric altitude and pressure requires accurate information on the vertical structure of the background atmosphere. In this study we compare atmospheric structure measurements routinely available from the National Meteorological Center with a special set of in situ measurements by radiosondes and meteorological rocketsondes. Furthermore, we demonstrate the manner in which the differences in these background atmosphere measurements propagate through the direct comparisons of stratospheric ozone profiles by SBUV and SAGE II sensors. Modest differences in vertical positioning can propagate into significant ozone differences in regions with strong vertical ozone gradients, particularly at 70 mbar in the tropics. We find apparent ozone differences of 5–10% or more due solely to these background atmosphere effects within an analysis for which the ozone observations themselves are treated as error‐free.

Evidence from balloon measurements for chemical depletion of stratospheric ozone in the Arctic winter of 1989–90

Measurements of the vertical ozone profile with balloon-borne sensors in the Arctic during January and February 1990 indicate repeated minima in the 22-km region. A general negative correlation of the 22-km ozone mixing ratio with time spent by the air parcel in regions cold enough for the formation of polar stratospheric clouds, together with the presence of sunlight on a portion of the air-parcel trajectory, and an inability to explain the ozone minimum by conventional dynamical processes, suggest that this feature is related to chemical ozone depletion.

On the mean daily and seasonal variations of the vertical ozone profiles in the lower troposphere

During the 15 year period that the Zugspitze cable car has operated between the valley (1 km a.s.l.) and Zugspitze peak (3 km a.s.l.) at the northern border of the Bavarian Alps, it has been used for investigating the profiles of meteorological and atmospheric electrical parameters, and Aitken nuclei. This cable railway is rather steep and is suspended mostly far away from the ground. From 1980 to 1982 nearly 2000 ozone profiles were additionalyrecorded. The data collected offer a profound basis in order to study the time variations of the lower tropospheric ozone profile depending on the hour of the day during all the seasons. In this paper the following are reported: the shape and time behaviour of ozone profiles in different seasons depending on the vertical mixing intensity, stratospheric intrusions and the penetration depth of the stratospheric O 3.

Spectroradiometer for groundbased atmospheric ozone studies in the 2-mm-wavelength range

A superheterodyne spectroradiometer for the 2-mm wavelength range suitable for atmospheric ozone observations has been described. Laboratory and field tests of the device have demonstrated its reliability and convenience for the important task of observing and reconstructing the vertical atmospheric ozone profile in inaccessible layers of the middle atmosphere. Further increase in the sensitivity of the device will be required.

Vertical ozone fluxes and related deposition parameters over agricultural and forested landscapes

The spatial variability and temporal behavior of the vertical flux of ozone have been investigated from turbulence measurements collected on aircraft flight legs in the daytime period during two consecutive summer experimental field programs. The data were obtained during horizontal flight legs conducted over agricultural crops and forested land in three different regions of the eastern United States.

Ozone reference models for the middle atmosphere

Data on monthly latitudinal variations in middle-atmosphere vertical ozone profiles are presented, based on extensive Nimbus-7, AE-2, and SME satellite measurements from the period 1978-1982. The coverage of the data sets, the characteristics of the sensors, and the analysis techniques applied are described, and the results are compiled in tables and graphs. These ozone data are intended to supplement the models of the 1986 COSPAR International Reference Atmosphere.

Vertical distributions of ozone in the lower stratosphere over Antarctica and their relations to the spring depletion

Three year observations of vertical ozone distributions (1985–1987) are analyzed, which have been gained by means of electrochemical ozone sondes (OSE-3) at GEORG FORSTER station (71°S; 12°E). This material and additional data of other stations are used to discuss the primary chemical origin of the spring time ozone depletion in connection with the dynamically conditioned variations of ozone distribution in the southern polar stratosphere. A mean pattern featured by three typlcal time periods of the ozone depletion using the height-time variations of pronounced maxima of the vertical ozone distribution is drawn to localize the chemical active region. During spring in 1987 the ozone variations are discussed in more detail to separate different dynamical impacts like an irregular outflow of ozone into the troposphere and the control of vertical ozone distribution by the dynamics of the southern polar stratospheric vortex itself. The special dynamical preconditions rendered it possible to use the height variations of stratospheric ozone as an indicator for the vertical diabatic circulation inside the polar stratospheric vortex.

Meridional and vertical ozone distribution in the background troposphere (70°n-60°s; 0–12 km altitude) from scientific aircraft measurements during the STRATOZ III experiment (june 1984)

During the STRATOZ III experiment (June 1984), aimed at studying several minor air constituents, more than 10,000 ozone measurements were made using u.v. absorption analysis during a series of flights aboard a “Caravelle 116” scientific aircraft. The flights were made over the Atlantic Ocean, and along the American, African and European continents, between 70°N and 60°S, and up to a cruising altitude of 12 km. While a comprehensive interpretation must await the data from the whole series of compounds measured, initial results concerning O 3 are presented here. The stratospheric and tropospheric O 3 contents are found to be significantly higher in the Northern Hemisphere than in the Southern. The data indicate an important photochemical formation of tropospheric O 3 at this time of the year, resulting from the anthropogenic pollution of industrialized areas of the Northern Hemisphere (North America, Europe). Except for West Africa, the tropical area (including the Caribbean and the northern part of South America) constitutes an important sink for tropospheric O 3, likely to be due to photochemical losses and air ascents. The detailed and coherent data presented here highlight the importance of photochemical processes in the distribution of tropospheric O 3.

Comparative morphology of the vertical ozone profile in the Antarctic spring

The form and development of the vertical distribution of ozone are examined during the Antarctic winter and spring by comparing profiles selected from a series of balloon‐borne ozonesonde ascents which were launched from Halley Bay in 1987. The progress of the ozone depletion is followed from its onset in late August until the deep minimum in mid‐October, when nearly all the ozone has been destroyed between 90 and 50 mbar. The presence of structure in the unperturbed profile is discussed, and it is shown that individual profiles are susceptible to the effects of vertical motion and wind shear. After the spring equinox, the vertical distribution of ozone consistently displays a minimum in mixing ratio, in contradiction to theories which purport to explain the spring development by transport alone. The depletion process is restricted to a finite vertical range of some 12 km, with a sharp upper boundary at about 20 mbar.

An improved method for determining the vertical ozone distribution using satellite measurements.

A procedure was developed for determining vertical ozone distributions from spectral measurements of UV radiances diffusely reflected from the terrestrial atmosphere. In this procedure, the inversion method of Aruga and Igarashi (1976) is improved by incorporating the effects of multiple scattering and the lower boundary of the atmosphere. The improved inversion algorithm was tested using data of NIMBUS-4 backscattered UV experiments. The results indicate that by using this method, the vertical distributions of atmospheric ozone can be obtained with high accuracy over a wide range of altitude.

Impact of Chlorofluoromethanes on Stratospheric Ozone

Abstract Monthly averages of data on stratospheric total ozone and vertical distribution ozone profiles from a global collection of ground-based recording stations are analyzed for the detection of trend in ozone that may be associated with possible effects of the release of chlorofluoromethanes (CFM's). Regression time series models that include seasonal, trend, and other factors are estimated from the data at each individual station. A factor to explicitly account empirically for the effects of atmospheric aerosols due to volcanic activity on the ozone profile measurements is also included in the models. A random effects model for the individual station trend estimates is used to combine the individual trend estimates in the form of an overall global estimate of trend in ozone. Based on analysis of ozone data during the period 1960-1983, there is little evidence of any trend in total ozone. But a statistically significant negative trend of about −.3% change per year for the period 1970-1981 has been obt...

Balloon-borne observations of the development and vertical structure of the Antarctic ozone hole in 1986

A springtime deficit in Antarctic stratospheric ozone has been developing over recent years1,2. Here we describe the vertical distribution of ozone which was measured at McMurdo Station, Antarctica (78 °S), using balloon borne sensors, on 33 occasions during the period 25 August–6 November 1986. These observations suggest a highly structured cavity confined to the 12–20 km altitude region. In the 17–19 km altitude range, the ozone volume mixing ratio declined from about 2 p.p.m. at the end of August to about 0.5 p.p.m. by mid-October. The average decay in this region can be described as exponential with a half life of about 25 days. While total ozone, as obtained from profile integration, declined only about 35%, the integrated ozone between 14 and 18 km declined more than 70%. Vertical ozone profiles in the vortex revealed unusual structure with major features from 1 to 5 km thick which had suffered ozone depletions as great as 90%.

The vertical ozone distribution above the GDR‐Research Base, Antarctica in 1985

Results of balloon borne soundings with electrochemical ozone sondes carried out at 70,77° S; 11,85° E are discussed. During polar spring in 1985 the high time resolution of soundings (about 12 launches per months) gives a detailed picture on the vertical distribution and height variations of different maxima of ozone partial pressure near the margin of the ozone hole crossing the continental coast above Queen Maud Land in recent time.

The Quasi-biennial Oscillation of Ozone in the Tropical Middle Stratosphere: A One-Dimensional Model

A one-dimensional model of the quasi-biennial oscillation (QBO) of ozone in the tropical middle stratosphere is derived based on assumed (observed) zonal wind QBO in a coupled dynamic, radiative/photochemical system. It is found that the derived vertical variation of the ozone QBO amplitude has two maxima, one at 32 km and the other at 22 km, and a minimum at 28 km. These are in qualitative agreement with observations. In the height interval 30-35 km, the ozone QBO is closely related to temperature dependent photochemistry, and the ozone and temperature variations are out of phase. Below 28 km, where vertical ozone and thermal transports are important, ozone and temperature oscillations are in phase, but both are approximately 270 deg out of phase with the vertical wind variation.

The vertical ozone distribution in the Antarctic ozone minimum measured by SBUV

The ozone profiles measured by SBUV in the region of the antarctic ozone minimum are in error as archived for altitudes below the 7 mb level in the atmosphere because of the lack of a reasonable climatology to use for the initial guess profile. We have examined the ozone profile error in this region and have shown that use of a reasonable climatology in this unusual region results in ozone profiles that agree substantially better with the balloon observations available from the Syowa station. The corrected profiles show that by 1984 there was 35% less ozone in the 15 to 30 km region than in 1979, and 14% less even in the 40 to 50 km region.

Atmospheric ozone monitoring in the Indian network in view of possibility of damage to the biosphere due to distortion of ozone layer

Atmospheric ozone protects life on the earth from harmful ultraviolet radiation of wavelengths in the biologically important 300nanometre region. In recent year many workers in the field of atmospheric ozone have brought out the various effects of oxides of nitrogen (NOx) Oxides of chlorine (CIOx) and Hydroxyl radicals (HOx) on the ozone layer due to man made activities. It has been demonstrated by recent studies that monsoon season these man made chemicals like NOx, ClOx released in the troposphere due to industrializations may eventually deplete ozone in the stratosphere by as much as 5% at the present rate of discharge of these chemicals in the lower troposphere. This depletion of total ozone could cause an increase in the incident of skin cancer. Furthermore these are indications of the possibility that plant life and marine life and other ecological systems are also affected cultural planning by the changes in ultraviolet radiation.
 The ozone layer in the stratosphere controls the temperature & winds in the stratosphere and have a great influence in the general circulation & climate of the earth. Depletion of ozone in the stratosphere due to man made actitives, may therefore cause adverse effects on the earth’s climate. Model calculation indicate that early next Century the combined radiative effects of ozone and other trace gases would be of the same order as that calculated for CO2.
 Recent studies in the field of tropospheric ozone have indicated that due to man made activities possibility of sharp increase in the tropospheric ozone particularly in the industrially developed countries. This increase in the tropospheric ozone could adversely effect human health and plant life particularly forest resources.
 It has, therefore, become very important to accurately monitor atmospheric ozone on a routine and network basis over the entire globe by insitu, balloon borne and satellite measurements. The present paper brings out the results and analysis of total ozone, vertical ozone measurements by Umkehr and balloon sonde and tropospheric ozone measurements by ground based and balloon borne sondes made in the Indian network during the last decade (1970-1979) and various aspects of ozone profiles and variations and ozone trend analysis over the years have been presented and discussed in this paper.