World Ozone Data Center Research Articles

On the solar/QBO effect on the interannual variability of total ozone and the stratospheric circulation over Northern Europe

Based on total ozone data from the World Ozone Data Center and stratospheric geopotential height data from the Meteorological Institute of Berlin Free University for the months of January through March for the time period of 1958–1996, the influence of the 11-year solar cycle and the equatorial quasi-biennial oscillation (QBO) on total ozone and the stratospheric circulation at 30 hPa over Northern Europe is investigated. The analysis is performed for different levels of solar activity. The relationship of the equatorial QBO with ozone and the stratospheric circulation over the study region exhibits unique features attributed to strong opposite connections between the equatorial zonal wind and ozone/stratospheric dynamics during periods of solar minimum and maximum. Using the Solar/QBO effect, a statistical extraction of the interannual variations of total ozone and stratospheric circulation over Northern Europe has been attempted. The variations extracted and observed for late winter show very good correspondence. The solar/QBO effect in total ozone and stratospheric dynamics over Northern Europe appears to be related to planetary wave activity.

A Study of Ozone Laminae Using Diabatic Trajectories, Contour Advection and Photochemical Trajectory Model Simulations.

In this paper, we show that the rate of ozone loss in both polar and mid-latitudes, derived from ozonesonde and satellite data, has almost the same vertical distribution (although opposite sense) to that of ozone laminae abundance. Ozone laminae appear in the lower stratosphere soon after the polar vortex is established in autumn, increase in number throughout the winter and reach a maximum abundance in late winter or spring. We indicate a possible coupling between mid-winter, sudden stratospheric warmings (when the vortex is weakened or disrupted) and the abundance of ozone laminae using a 23-year record of ozonesonde data from the World Ozone Data Center in Canada combined with monthly-mean January polar temperatures at 30 hPa.Results are presented from an experiment conducted during the winter of 1994/95, in phase II of the Second European Stratospheric And Mid-latitude Experiment (SESAME), in which 93 ozone-enhanced laminae of polar origin observed by ozonesondes at different time and locations are linked by diabatic trajectories, enabling them to be probed twice or more. It is shown that, in general, ozone concentrations inside laminae fall progressively with time, mixing irreversibly with mid-latitude air on time-scales of a few weeks.A particular set of laminae which advected across Europe during mid February 1995 are examined in detail. These laminae were observed almost simultaneously at seven ozonesonde stations, providing information on their spatial scales. The development of these laminae has been modelled using the Contour Advection algorithm of Norton (1994), adding support to the concept that many laminae are extrusions of vortex air. Finally, a photochemical trajectory model is used to show that, if the air in the laminae is chemically activated, it will impact on mid-latitude ozone concentrations. An estimate is made of the potential number of ozone molecules lost each winter via this mechanism.

Total ozone changes over Eurasia since 1973 based on reevaluated filter ozonometer data

Since the early 1960s, on the vast territory of the former USSR, 45 stations have been in continuous operation, utilizing the broadband filter M‐83 ozonometer. The quality of the ozone data during the first decade was unsatisfactory. After 1972 an improved version of the ozonometer was introduced together with improved quality control practices, including methodology of observations. The more reliable data of 1973 through March 1994 have been rigorously reexamined by applying variability analysis, comparison with lower‐stratosphere temperatures and/or nearby Dobson stations, and overpassing TOMS for identifying concurrence or discrepancies. These control procedures together with the information on instrument relocation and calibrations made it possible to reevaluate the record of all 45 stations. The accuracy of the improved ozonometer data is about 3% for direct Sun measurements and ∼5% for zenith sky observations; although not so good as that of the Dobson, in the long run it provides consistent ozone data sets. This data set is now made available to the World Ozone Data Center (WO3DC), Toronto. Thus for the first time, based on a 21‐year long record, information is deduced on the differences in the ozone annual cycle between Eastern Siberia and the European part, on the strong appearance of quasi‐biennial oscillation (QBO) signals especially pronounced as ozone deficiency during the western phase of the QBO, on the ozone variability, and on the long‐term changes over the huge territory from Central Europe to the Far East. The specifics of the ozone changes considered in concurrence with the prevailing general stratospheric circulation conditions permitted us to distinguish four broad regions with consistent ozone regimes. The appearance of the strongest northern hemisphere ozone maximum and a monthly mean of ∼470 matm cm over Siberia during winter‐spring, compared with ∼400 matm cm over Europe, the occurrence of the ozone annual minimums as early as August over Eastern Siberia, compared with October over the European part, was established and is probably related to the specifics of the atmospheric circulation patterns. The long‐term ozone changes are considered in relation to the stratospheric temperature at 100‐hPa. For each deviation from the monthly normal temperature by 1°C, there is a corresponding change by the same sign 5–6 matm cm in the monthly ozone deviations. The calculated long‐term ozone trends for 1973 through March 1994 (given in percent per decade ±2σ) are as follows: European part, −3.6±0.8; Central Asia, −2.0±0.6; Western Siberia, −3.5±0.8; and Eastern Siberia ‐ Far East, −3.2±0.8. They show a steady ozone decline similar to that deduced from the Dobson stations at the same latitudes. The decline during the past 15 years is stronger and, in general, concurs with Total Ozone Mapping Spectrometer (TOMS) trends which are, however, slightly more negative.

Three years of total ozone measurements over Athens obtained using the remote sensing technique of a Dobson spectrophotometer

Abstract Total ozone measurements with a Dobson spectrophotometer (No. 118) have been instituted in Athens (37.9° N, 23.8° E) from 1989 and they now form part of the data published by the World Meteorological Organization, World Ozone Data Center. We have used this data set in order to examine the consistency of data from the Total Ozone Mapping Spectrometer (flown on the Nimbus-7 satellite) with the corresponding Dobson data on a daily basis. The results show that the Athens station may be used to provide ground truth for satellite-based total ozone measurements and also for providing reasonably accurate total ozone values for south eastern Europe.

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.

On the Application of the Optimum Statistical Inversion Technique to the Evaluation of Umkehr Observations

The optimum statistical inversion technique is applied to the evaluation of Umkehr observations from Arosa (46.5N, 9.4E), Aspendale (38.0S, 145.IE) and Tallahassee (30.2N, 84.2W). A Priori statistical information on the vertical ozone distribution is obtained from 511 balloon-sounding profiles at Boulder (40.0N, 105.1W). These latter data are also used to develop a regression method for obtaining a first guess at the O2 distribution, using total O2 as the independent variable. The ozone profiles inferred from the statistical method, when compared with concurrent direct measurements, display a significant improvement over profiles derived by the method in use at the World Ozone Data Center, Most of this improvement is attributable to the better first guess based on the total O2 regression. It is concluded that the utility of Umkehr observations is mainly restricted to estimation of the high-level O2 distribution above the main O2 maximum. For inferences about the ozone distribution at and below the maximum, effort should be directed toward regression techniques using total ozone as the independent variable.

Effect of the temperature dependence of ozone absorption on vertical ozone distributions deduced from Umkehr observations

Ozone distributions deduced from Umkehr observations are subject to error if the temperature dependence of ozone absorption has not been included in the development of an inversion system. An estimation of the error is made for the World Ozone Data Center Umkehr inversion system in the following way: Umkehr curves are computed for temperature dependent ozone absorption coefficients and for absorption coefficients at −44°C; then, ozone distributions are deduced from these curves and are compared for midlatitude summer and winter situations. Significant differences arise and their cause is discussed. It is suggested that any future work on the development of inversion systems for indirect observation of the vertical ozone distribution include a compensation for the temperature dependence of ozone absorption.