Total Ozone Content Research Articles

The effect of planetary waves on the total ozone zonal deviations in the presence of a persistent blocking anticyclone system

Strong planetary wave activity enhanced by the external forcing of a persisting anticyclone system can cause large total ozone zonal deviations. In January 1992 such a situation was observed with a high‐pressure system and associated low total ozone concentrations situated over Northern Europe. In this article, measurements from the total ozone mapping spectrometer (TOMS) are analyzed with a simple model based on the linearized stationary ozone continuity equation. It is shown that in such a meteorological situation, vertical advection of ozone caused by the wavenumber‐one quasi‐stationary planetary wave is the most important monthly mean transport mechanism. This is different from the climatological situation, where horizontal and vertical advection are almost equally important and where wavenumbers two and three contribute more to the total ozone zonal deviations. The dominance of vertical motions, which are in phase throughout the lower and middle stratosphere, also explains the high correlations found between temperatures at 50 hPa from National Meteorological Center analyses and total ozone. Under these special meteorological conditions, the high planetary wave activity is responsible for total ozone columns with about 60 Dobson units less ozone over the anticyclonic region than under normal conditions.

Ozone peaks associated with a subtropical tropopause fold and with the trade wind inversion: A case study from the airborne campaign TROPOZ II over the Caribbean in winter

Aircraft measurements of ozone, methane, carbon monoxide, relative humidity, and equivalent potential temperature were performed during the TROPOZ II campaign. During the aircraft descent down to Pointe‐à‐Pitre (16.3°N, 61.5°W), at 2100 UTC on January 12, 1991, two ozone peaks (75 ppb) are observed, one at an altitude of 7.5 km and the other at 3.0 km. A physicochemical interpretation for each ozone peak is proposed in connection with the meteorological context, using radiosounding data, total ozone content from TOMS/NIMBUS 7 and diagnoses issued from analyses by the European Centre for Medium‐Range Weather Forecasts, Reading, England. The stratospheric origin of the 7.5‐km ozone peak is inferred from negative correlations between ozone and its precursors and from diagnoses based on potential vorticity and ageostrophic circulations depicting the structure of the tropopause fold embedded in the subtropical jet front system. Using an appropriate method to isolate cross‐ and along‐front ageostrophic circulations, we show that much of the observed structure of the tropopause fold can be ascribed to transverse and vertical circulations associated with the irrotational part of the flow. Though the downward extent of the subtropical tropopause fold (400 hPa) is restricted in comparison with typical extratropical tropopause ones (700 hPa), the present results suggest that subtropical tropopause folds may significantly contribute to the global stratosphere‐troposphere ozone exchange. The origin of the 3.0‐km ozone peak trapped just below the trade wind inversion cannot be ascribed precisely. Analogies with other measurements of dust and aerosols transported over the Atlantic or Pacific in the summer season are discussed. Various possibilities are examined: (1) an earlier stratospheric intrusion event, (2) long‐range transport by the trade winds of biomass burning species emitted over West Africa, and (3) fast photochemical ozone formation occurring just below the trade wind inversion within already polluted air parcels originating from remote regions (United States and Gulf of Mexico) after eastward and southward transport around the western Atlantic anticyclone.

Analysis of laminated structure in ozone vertical profiles in central Europe

Abstract. Using statistical techniques, we study the relationship between the long-term changes in the laminar structure of the ozone vertical profile at two central-European stations - Hohenpeissenberg and Lindenberg - and other quantities potentially affecting the state of the lower stratosphere, and total-ozone content. We consider only positive laminae greater than 30 nbar. Laminae contribute non-negligibly to total ozone, and this contribution varies strongly with season. The maximum laminae-occurrence frequency in late winter/early spring is five-times higher than the minimum in early autumn. The main result of the paper is the discovery of a strong negative trend in the frequency of laminae occurrence, about –15% per decade, and even a slightly stronger negative trend in ozone content in laminae. Strong negative trends in laminae occurrence imply negative changes in total ozone as well. No pronounced effect of the quasi-biennial oscillation and solar cycle on laminae was found, whereas the 100-hPa temperature had a clear effect, and there was an indication of substantial effects of volcanic eruptions and El Niño southern oscillation events. Long-term changes in individual time series of meteorological parameters measured over Hohenpeissenberg do not indicate their significant role in the observed trend in laminae occurrence. On the other hand, there is some increase in the occurrence of very zonal circulation patterns, as well as slight decrease in very meridional circulation patterns. Together with other indications this allows us to say that dynamical effects are expected to be a principal contributor. Thus changes in laminae occurrence will probably be able to serve as an indicator/tracer of long-term changes in lower-stratospheric dynamics.

MEASUREMENT OF TOTAL OZONE CONTENT FROM SATELLITE AND SURFACE OBSERVATIONS

Results are reported of a comparative analysis of information obtained on total ozone content (TOC), using simultaneously recorded data from satellite (TOMS and SBUV instrumentation) and surface (D...

Analysis of laminated structure in ozone vertical profiles in central Europe

Using statistical techniques, we study the relationship between the long-term changes in the laminar structure of the ozone vertical profile at two central-European stations - Hohenpeissenberg and Lindenberg - and other quantities potentially affecting the state of the lower stratosphere, and total-ozone content. We consider only positive laminae greater than 30 nbar. Laminae contribute non-negligibly to total ozone, and this contribution varies strongly with season. The maximum laminae-occurrence frequency in late winter/early spring is five-times higher than the minimum in early autumn. The main result of the paper is the discovery of a strong negative trend in the frequency of laminae occurrence, about –15% per decade, and even a slightly stronger negative trend in ozone content in laminae. Strong negative trends in laminae occurrence imply negative changes in total ozone as well. No pronounced effect of the quasi-biennial oscillation and solar cycle on laminae was found, whereas the 100-hPa temperature had a clear effect, and there was an indication of substantial effects of volcanic eruptions and El Niño southern oscillation events. Long-term changes in individual time series of meteorological parameters measured over Hohenpeissenberg do not indicate their significant role in the observed trend in laminae occurrence. On the other hand, there is some increase in the occurrence of very zonal circulation patterns, as well as slight decrease in very meridional circulation patterns. Together with other indications this allows us to say that dynamical effects are expected to be a principal contributor. Thus changes in laminae occurrence will probably be able to serve as an indicator/tracer of long-term changes in lower-stratospheric dynamics.

Technical Note The use of TOMS data in the calculation of atmospheric turbidity parameters

Abstract The effect of the recently proposed pattern of the total ozone trend over the middle latitudes of the Northern Hemisphere on the van Heuklon model is examined. The errors in the estimates of this model for the total ozone content are large. Also the errors in the Unsworth-Monteith atmospheric turbidity parameter associated with using the van Heuklon model are substantial and vary quite significantly according to the season.

Technical Note Infrared remote sensing of total ozone content around the Indian region

Abstract The total ozone in the vertical column in the atmosphere has been determined using infrared sensor data onboard the NOAA series-of polar meteorological satellites for the months of April and July during the period 1979-1986. The estimation is compared with observed data from the Indian stations. The total ozone values are within 16 Dobson Units.

Indian experience in ground based experiments in support of satellite data applications

Indian space programme is primarily directed to operationalise the regional and global applications of understanding and monitoring land, ocean and aerological processes using space platforms. Data from indigenous satellite series such as IRS, INSAT and SROSS, as well as foreign satellites of the type NOAA, NIMBUS, LANDSAT, SPOT and ERS have been utilised along with concurrent ground based measurements for the implementation of this programme. Carefully selected ground based experiments in association with satellite borne observations have been blended to investigate a number of phenomena relating to forest cover and volume, crop yield and biomass estimation, rainfall characteristics, evapotranspiration, soil moisture, snow cover and snow melt run-off and sea-surface temperatures. Optical, infrared and microwave remote sensing data from different satellites have been used in these studies and efforts are being made continuously to bring these to operational levels with supportive information from ground based instruments. Investigations have also been pursued in the areas of total ozone content and ground reaching solar B-UV fluxes, atmospheric aerosol distribution and its impact particularly during major volcanic eruptions, methane emission from rice paddy fields enhancing the greenhouse potential and the electrodynamics of ionospheric plasma and generation of spread-F irregularities. For these studies, both satellite borne and ground based data have been effectively combined to bring out the details of the physical mechanisms governing these phenomena. A few specific examples of the integrated ground based and space borne observations in the above areas of applications are presented. Such efforts are expected to lead to better modelling of our ecoenvironmental system, monsoon dynamics, weather and climate variations.

The possible coupling of the stratosphere and lower ionosphere at middle latitudes

A study is presented about the possible coupling of the stratosphere and the lower ionosphere supported by analysis of total ozone content and ionospheric radio waves absorption data obtained by A3 method (oblique incidence) for some radiopaths and the ozone data obtained by groundbased Dobson spectrophotometers and by Total Ozone Mapping Spectrometer (TOMS/NASA) near the radiowaves reflection points. The data were obtained for Southern Spain, Czechia and Bulgaria. Some statistically significant correlations between variations of total ozone content considered as a measure of the stratospheric changes and radio waves absorption as an indicator of the lower ionosphere behaviour are interpreted as a consequence of the trace gases transport which are of importance for the neutral and ion chemistry of the ionospheric D-region and ozone chemistry.

Total ozone variations in middle Asia and dynamic meteorological processes in the atmosphere

The total ozone content over the former Soviet Middle Asia is compared with the heights and the temperatures at the 500 hPa and 100 hPa levels. There is a significant and negative correlation between the heights of the 100 hPa and 500 hPa levels and the total ozone content. The ozone column density is positively correlated with the temperature at 100 hPa and negatively correlated at 500 hPa. No observed time delay between ozone and temperature changes is found, indicating that the correlations are caused by dynamic processes. Ozone changes due to chemistry have time constants at least of the order of days, but correspondingly large time delays are not found. It is concluded that the horizontal advection is connected with ascending and descending air streams, and they are the main causes of decrease and increase of total ozone content with time constants of the order of one day.

On the association between the column ozone and the spectral solar ultraviolet radiation

An estimation of the increase in the daily spectral solar ultraviolet radiation reaching the ground is attempted, by using the daily total ozone observations made by the Total Ozone Mapping Spectrometer (TOMS) flown on the satellite Nimbus‐7 during 1978–1992. This investigation has been performed for the high latitudes by employing a recently proposed parametric model for the estimation of the spectral solar ultraviolet radiation at the earth's surface considering the total ozone content and various meteorological parameters.

On a method of microwave measurement of ozone

A procedure for determination of the ozone total content and the vertical profile at altitudes of 20–50 km from microwave measurement data is considered. Estimates of possible errors are made, and suggestions aimed at reduction of these errors are considered.

Recent trends of the total column ozone: implications for the Mediterranean region

Abstract The daily ozone column amounts during the 14-year period (1979–1992), which are inferred from measurements made with both the Total Ozone Mapping Spectrometer (TOMS) mounted on board the Nimbus-7 satellite have been used to study longitudinal trends at mid-latitudes. The main findings are: (1) There is a large longitudinal variation of the monthly trend in total ozone over the northern mid-latitudes ranging from 1.5 to 8.5 per cent per year with a large standard error, (2) The trend in the total ozone content over the Mediterranean area varies in a similar way with the zonal average total ozone trend over mid-latitudes. Also, the trend of the total ozone over Athens, Greece, is representative of the whole Mediterranean region and so it is representative of the zonal average total ozone trend over the northern mid-latitudes, and (3) The interannual variability of the amplitude of the annual wave in the total ozone amount over the Mediterranean region compares extremely well with the interannual variability of the total ozone amount over this location.

On the correction of the total ozone content over Athens, Greece as deduced from satellite observations

Abstract The observations with the Total Ozone Mapping Spectrometer ( TOMS) mounted aboard the Nimbus-7 satellite have previously been used to determine the trends of the total ozone amount over Athens, Greece ( 38° N, 24° E), since 1979, for various months ( Varotsos, C. A., and Cracknell, A. P., 1993, International Journal of Remote Sensing, 14, 2053–2059). The total ozone depletion over the 13-year time period showed a strong seasonal variation of the trend from more than 7 per cent in winter to about 2·5 per cent in summer. However, the TOMS instrument measures the back-scattered ultraviolet radiation in order to determine ozone content and is limited to observations above the cloud level. ln the presence of thick cloud the column ozone content is generally underestimated. This underestimation of the total ozone amount is quantitatively examined, especially in the synoptic cases where ozone-rich air has been transported into the lower troposphere. The influence of this underestimation on the total ozone depletion over Athens, Greece, deduced from TOMS observations, is finally attempted.

On the solar ultraviolet spectral irradiance during the Maunder Minimum

In the historical record of solar activity the period from 1645 to 1715 is a singular epoch during which the number of sunspots decreased markedly for a generation. Known as the Maunder Minimum, this solar epoch coincided with the coldest part of the Little Ice Age (circa 1450 to 1850). We estimate the change at this time in the output of solar ultraviolet (UV) radiation at wavelengths from 120 to 300 nm, relative to contemporary observations. Since this portion of the solar UV spectrum determines ozone composition in the stratosphere, our results bear on the historical variability of ozone and its potential climatic effects. Between the Maunder Minimum and 1986 (the present day solar activity minimum between cycles 21 and 22) we estimate reductions of 64% in the irradiance of the Lyman α line of neutral hydrogen (at 121.6 nm), 8% at 200 nm, and 3.5% in the wavelength range from 210 to 250 nm. The reduction in the solar output from the entire spectral band between 120 and 300 nm is estimated to be 0.17 W/m2, which is approximately 6% of the change in the total solar irradiance of 2.7 W/m2 previously estimated by us (Lean et al., 1992a) over the same time span. Because of this diminished UV output due to very low solar activity the Maunder Minimum total ozone concentration may have been 4% below its 1980 level. While the climatic consequences of such a change have yet to be determined, recent work by Haigh (1994) on modulation of radiative climate forcing by stratospheric ozone emphasizes the need to understand the role of UV irradiance variability as one forcing mechanism.

Ozone “miniholes” initiated by energetic solar protons

In this study, it is shown that during four Solar Proton Events (SPE), mostly of the Ground Level Event (GLE) type (May 1990, September and October 1989, and March 1989), inside the polar cap in the Arctic (or the Antarctic) short-term depletions were observed (up to 20%) in the ozone total content. These depletions or so-called ozone “miniholes” seem to be caused by energetic solar protons with energies of 150–300 MeV. For May 1990, the gas phase photochemical model includes only 1% ozone depletion compared with 18% observed at Barentsburg (Svalbard), and for none of the other events can homogeneous processes explain the observed depletion. The problem seems to be solved considering heterogeneous reactions in the presence of increased amounts of aerosol particles in the stratosphere which may be triggered by penetrating solar protons, or through an additional decrease of temperature, or through an increase of volume electric charge in the stratosphere (or even troposphere).

Ozone “miniholes” initiated by energetic solar protons

In this study, it is shown that during four Solar Proton Events (SPE), mostly of the Ground Level Event (GLE) type (May 1990, September and October 1989, and March 1989), inside the polar cap in the Arctic (or the Antarctic) short-term depletions were observed (up to 20%) in the ozone total content. These depletions or so-called ozone “miniholes” seem to be caused by energetic solar protons with energies of 150–300 MeV. For May 1990, the gas phase photochemical model includes only 1% ozone depletion compared with 18% observed at Barentsburg (Svalbard), and for none of the other events can homogeneous processes explain the observed depletion. The problem seems to be solved considering heterogeneous reactions in the presence of increased amounts of aerosol particles in the stratosphere which may be triggered by penetrating solar protons, or through an additional decrease of temperature, or through an increase of volume electric charge in the stratosphere (or even troposphere).

Temporal variations of the total ozone content over Greece as deduced from satellite observations

The observations with the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus‐7 satellite have previously been used to assess the trends of the total ozone content over Athens, Greece (38°N, 24°E), since 1978, for various months. In the present paper we report some new calculations in which we have taken steps to exclude the effects of biennial and tri‐annual oscillations from the trend analysis. The results show that the natural fluctuations of the total ozone content due to these oscillations have little effect on the calculated total ozone depletion trend, over a 13‐year period, compared with the strong variations of the total ozone depletion trend from month to month due to other causes.

Dynamical aspects of ozone mini-hole formation

A case study and statistical evaluations provide evidence that so-called ozone mini-hole events over Europe, where a rapid drop of total ozone is followed by complete recovery after a few days, are due to the northeascward motion of patches of air with low total ozone content. These patches appear to originate in subtropical latitudes. They correlate well with minima of potential vorticity near the tropopause. Contour dynamics is invoked to explain some basic features of the deformation and northward motion of the mini-holes as well as the related large-scale flow structures.

Temporal variations of the total ozone content over St. Petersburg

The observations with the Dobson spectrophotometer and the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus‐7 satellite have been used to assess the trends of the total ozone content over St. Petersburg (60°N, 30°E), since 1968 and 1978, respectively, for various months. The analysis performed shows that the natural fluctuations of the total ozone content due to Quasi ‐Biennual Oscillation and EI Nino/Southern Oscillation have minor contribution to the total ozone depletion trend comparing with the strong variations of the total ozone depletion trend from month to month due to other causes.