Synoptic-scale fluctuations of total ozone in the atmosphere

A model, based on ozone-concentration tendency equation, is developed to study synoptic ozone-column variations. The application is referred to a middle-latitude site and to an atmospheric layer extending from the surface up to about 35-km altitude. Photochemical effects at the considered location for synoptic time scales are considered negligible. The data input consists of umkehr ozone profile, total ozone (obtained by Brewer No. 067, located at Rome) and horizontal wind at various levels. Analysis of several cases indicates that meridional advection is the main factor responsible for the observed synoptic-scale ozone fluctuations.     

The early history of oxygen and ozone in the atmosphere

There may have been three stages in the growth of oxygen in the terrestrial atmosphere. Prior to the origin of photosynthesis the only source of oxygen was photolysis of water vapor followed by escape of hydrogen to space. The rate of this process was probably less than the rate of release of reduced gases (principally hydrogen) from volcanoes, so the oxygen partial pressure was held to negligibly low values by photochemical reactions with an excess of hydrogen. The photosynthetic source of oxygen was probably in operation as long ago as 3.8 billion years. It released oxygen to the ocean. Presumably most of this oxygen was destroyed in the ocean as long as its rate of supply was less than the rate of supply of readily oxidizable material (principally Fe²⁺) provided by the weathering of rocks. This phase appears to have lasted until about 2 billion years ago, during which period most banded iron formations were deposited. During this period the production of oxygen by algae was limited by competition with photosynthetic bacteria, which preempted the supply of nutrient phosphorus as long as reduced chemicals were available in the environment. Once the photosynthetic oxygen source exceeded the rate of supply of reduced minerals exposed by erosion and weathering, the accumulation of oxygen in the ocean and atmosphere could be controlled only by reaction of oxygen with reduced organic material. This is the stabilization mechanism that operates today. It seems unlikely that oxygen could be consumed at a significant rate by this process until oxygen levels sufficiently high to support respiration had been achieved. I therefore suggest that atmospheric oxygen rose rapidly from essentially zero to approximately its present value (within a factor of 10) when the photosynthetic source of oxygen rose above the weathering source of reduced minerals, probably about 2 billion years ago. The ozone layer and the ultraviolet screen were absent prior to this time and essentially fully developed after this time.Presented at IAGA/IAMAP Symposium on Minor Neutral Constituents in Middle Atmosphere-Chemistry and Transport, Seattle, August, 1977.     

Ozone content of the atmosphere. 3. Statistics of extreme values of the total ozone content in the midlatitude atmosphere

The occurrence frequency of extremely large and extremely small values of the total ozone content (TOC) for Irkutsk, Berlin, and Saskatoon midlatitude stations (located near 52°N but in different climatic zones) are calculated based on the daily satellite measurements in the 1978–2005 period. The data for various seasons are presented. The interannual variability and regional differences are demonstrated. The results indicate that the TOC variability is mainly caused by natural atmospheric processes.     

Relative importance of ozone energy transfer processes in the middle and upper atmosphere

The relative importance of different processes and transitions in the appearance of non-LTE populations for the fundamental levels of ozone was studied by quantifying the kinetic law of every process and transition that affect each level population. The vibrational temperatures and the relative contribution of every transition are presented as a function of altitude. The results show that the appearance of non-LTE populations for the fundamental levels is not produced by a direct imbalance between absorption and emission but as a consequence of imbalanced collisional transitions provoked by the overpopulation of O₃(0 v₂ 0) levels. This fact confirms that the relaxation cascade drives through the bending mode ν₂.     

Surface ozone variation associated with rainfall

Using an electrochemical surface ozone recorder, continuous monitoring of surface ozone is being carried out at Trivandrum (8°29N, 76°57E). A study of those surface ozone data together with rainfall and temperature reveals certain variations in ozone associated with rainfall, apart from other established variations reported so far. While daytime rainfall brings a decrease in surface ozone, nighttime rainfall produces an increase. The change in the surface ozone persists for a longer duration than the rainfall.     

Use of coupled ozone fields in a 3-D circulation model of the middle atmosphere

With a detailed chemistry scheme for the middle atmosphere up to 70 km which has been added to the 3-D Karlsruhe simulation model of the middle atmosphere (KASIMA), the effects of coupling chemistry and dynamics through ozone are studied for the middle atmosphere. An uncoupled version using an ozone climatology for determining heating rates and a coupled version using on-line ozone are compared in a 10-month integration with meteorological analyses for the winter 1992/93 as the lower boundary condition. Both versions simulate the meteorological situation satisfactorily, but exhibit a too cold lower stratosphere. The on-line ozone differs from the climatological data between 20 and 40 km by exhibiting too high ozone values, whereas in the lower mesosphere the ozone values are too low. The coupled model version is stable and differs only above 40 km significantly from the uncoupled version. Direct heating effects are identified to cause most of the differences. The well-known negative correlation between temperature and ozone is reproduced in the model. As a result, the coupled version slightly approaches the climatological ozone field. Further feedback effects are studied by using the on-line ozone field as a basis for an artificial climatology. For non-disturbed ozone conditions realistic monthly and zonally averaged ozone data are sufficient to determine the heating rates for modelling the middle atmosphere.     

Ozone content of the atmosphere. 2. Variability of the total ozone content in the atmosphere and the horizontal wind in the lower thermosphere (Central Europe)

The correlation between total ozone content lower thermosphere horizontal wind parameters, and standard indices of solar activity and geomagnetic activity has been studied. The satellite measurements of TOC for five observatories in Central Europe and the lower thermosphere wind measurements for Collm observatory (Germany) were used for 1996–2003. The quasi-periodic structure of these variations and the correlation between the corresponding periodograms were also studied. The quantitative evaluation of the statistically significant correlations and common periodicities were revealed.     

Variations of the total amount of ozone and the behaviour of some ionospheric parameters in the winter time upper atmosphere

Pure and Applied Geophysics -     

Model studies of the influence of O2 photodissociation parameterizations in the Schumann-Runge bands on ozone related photolysis in the upper atmosphere

A new parameterization for atmospheric transmission and O₂ photodissociation in the Schumann-Runge band region has been developed and tested with a 1D radiative-photochemical model. The parameterization is based on the O₂-column along the line of sight to the Sun and the local temperature. Line-by-line calculations have served as a benchmark for testing this method and several other, commonly used, parameterizations. The comparisons suggest that differences between the line-by-line calculations and currently accepted parameterizations can be reduced significantly by using the new method, particularly at large solar zenith angles. The production rate of O-atoms computed with this method shows less than 6% deviation compared to the line-by-line calculations at any altitude, all solar zenith angles and in all seasons. The largest errors are found toward the shorter wavelengths in the Schumann-Runge region at low altitudes. Transmittance is approximated to better than 4% at any altitude and/or solar zenith angle. The total O-production rate above 20 km is approximated to better than 2%. The new parameterization is easily implemented in existing photochemical models and in many cases it may simply replace the existing algorithm. The computational effort exceeds that of other parameterizations but in view of the total computation time needed for the actual calculation of the parameterized Schumann-Runge bands this should not lead to significant performance degeneration. The first 14 coefficients of the parameterization are included in this study. Both the complete sets of coefficients and a simple algorithm can be obtained by contacting the authors. A photochemical model study shows the largest effect of the parameterization method is on odd hydrogen concentrations. Subsequent interaction with an odd oxygen family causes differences in the ozone concentrations between the different parameterizations of more than 10% at selected altitudes. Although it is already established that deficiencies in the treatment of Schumann-Runge band absorption are unlikely to explain the current underestimation of ozone concentration at the stratopause in a variety of photochemical models, this study does show that the choice of parameterization has a large impact on the accuracy of the results at large solar zenith angles and in different seasons.     

Numerical simulation of the influence of stationary mesoscale orographic waves on the meridional circulation and ozone fluxes in the middle atmosphere

The authors’ parameterization of the dynamic and thermal action of stationary orographic waves generated by the Earth’s surface relief is included into the model of general circulation of the middle and upper atmosphere. Numerical simulation of the general circulation in the troposphere and stratosphere was performed and the influence of stationary orographic waves propagating upward from the Earth’s surface on the meridional and vertical velocity was studied. It is shown that the allowance for the dynamic and thermal action of these waves in the numerical model leads to changes by up to 20–30% in the meridional circulation and ozone fluxes associated with it at heights of the ozone layer maximum.     

Hydrocarbons in the atmosphere

Trace concentrations of highly reactive hydrocarbons of biogenic origin have been proposed for some time as being important in aerosol formation processes in the atmosphere. More recently, assessments of potential photochemical reactions in the troposphere have proposed a role in the atmospheric ozone cycle for hydrocarbons, even for compounds such as methane that had previously been considered nonreactive. An assessment of the atmospheric hydrocarbon reaction system has been limited by a lack of observational information on the nature of conditions in the remote or non-urban atmosphere. Recent data on terpene concentrations and other biogenic hydrocarbon compounds are presented. Data on ethane and acetylene from aircraft samples taken over the north and south Pacific Ocean show concentrations in the 0.5 to 1 /m³ range for ethane and in the 0.05 to 0.3 g/m³ range for acetylene. A concentration gradient is present for these compounds between the northern and southern hemisphere. A rudimentary global concentration pattern for these C₂ compounds has been developed on the basis of recent data.     

Further ozone transport calculations and the spring maximum in ozone amount

Summary Calculations of the covariance between ozone amounts and meridional wind in the lower stratosphere are presented for all stations in the northern hemisphere for the IGY-IGC. Northward ozone transport occurs by large-scale quasi-horizontal transient and standing eddies and the transport is a maximum early in the year. It is suggested that the transport is governed by the exchange of energy between the troposphere and stratosphere and data are presented on the energy transformations within the lower stratosphere and the transfer of energy into the region which support this suggestion. The vertical flux of energy is also calculated from tropospheric data and its seasonal changes are seen to be in the correct phase to explain the spring maximum in ozone amount.The research reported in this article was sponsored by the Atomic Energy Commission under Contract AT (30-1)2241.     

Acoustic-gravity modons in the atmosphere

It is shown that the equations governing low-frequency acoustic-gravity waves in a stable stratified atmosphere can have localized dipole-vortex solutions (modons). They propagate in the horizontal direction with a speed that is larger than that of all possible linear internal waves.     

Vortex streets in the earth's atmosphere

Summary Calculations of the Heisenberg parameter and Strouhal number, for mesoscale vortex streets in the atmosphere, support the analogy with the classical Kármán vortex wake. Revised estimates of the horizontal coefficient of eddy diffusion are obtained.     

A thermal cycle in the atmosphere

Summary It is shown that in order for a steady-state closed circulation to be maintained in the atmosphere, the working of the pressure force on a particle moving round the closed circuit is exactly balanced by the working of the particle against friction. It is concluded that sources of heat are associated with low surface pressure, and sinks with high surface pressure. This association of sources and sinkswith low and high surface pressure is verified, for circulations ranging in scale from that associated with an individual cumulus cloud to large-scale monsoonal systems.     

On sea-salt nuclei in the atmosphere

Summary The residues of cloud droplets collected at the summit of a mountain were examined with an electron microscope and their materials were identified with the aid of micro-electron-diffraction method. About 30% of nuclei of cloud droplets larger than 5 in radius were mainly composed of sodium chloride and their masses were 10^–1210^–13 gr. We also found salt particles in snow crystals. Some discussions are made about the process of the capture of these particles by snow crystals.     

Optical measurement in the middle atmosphere

The various measurement techniques and general problems in remote orin situ optical measurement of atmospheric minor gases are described.     

Temperature and ozone variations in the stratosphere

Examined are temperature and ozone variations in the Northern Hemisphere stratosphere during the period 1958–77, as estimated from radiosondes rocketsondes, ozonesondes, and Umkehr measurements. The temperature variation in the low tropical stratosphere is a combination of the variation associated with the quasi-biennial oscillation, and a variation nearly out of phase with the pronounced 3-yearly temperature oscillation (Southern Oscillation) present in the tropical troposphere since 1963. Based on radiosonde and rocketsonde data, the quasibiennial temperature oscillation can be traced as high as the stratopause, the phase varying with both height and latitude. However, the rocketsonde-derived temperature decrease of several degrees Celsius in the 25–55 km layer of the Western Hemisphere between 1969 (sunspot maximum) and 1976 (sunspot minimum) is not apparent in high-level radiosonde data, so that caution is advised with respect to a possible solar-terrestrial relation.There has been a strong quasi-biennial oscillation in ozone in the 8–16 km layer of the north polar region, with ozone minimum near the time of quasi-biennial west wind maximum at a height of 20 km in the tropics. A quasi-biennial oscillation in ozone (of similar phase) is also apparent from both ozonesonde data and Umkehr measurements in 8–16 and 16–24 km layers of north temperate latitudes, but not higher up. Both measurement techniques also suggest a slight overall ozone decrease in the same layers between 1969 and 1976, but no overall ozone change in the 24–32 km layer. Umkehr measurements indicate a significant 6–8% increase in ozone amount in all stratospheric layers between 1964 and 1970, and in 1977 the ozone amount in the 32–46 km layer was still 4% above average despite the predicted depletion due to fluorocarbon emissions. The decrease in ozone in the 32–46 km, layer of mid latitudes following the volcanic eruptions of Agung and Fuego is believed to be mostly fictitious and due to the bias introduced into the Umkehr technique by stratospheric aerosols of volcanic origin. Above-average water vapor amounts in the low stratosphere at Washington, DC, appear closely related to warm tropospheric temperatures in the tropics, presumably reflecting variations in strength of the Hadley circulation.     

Modelling the martian atmosphere

Stephen R Lewis shows how to model the climate of Mars, touching on the physics and dynamics of general circulation models, and the wealth of information that such models both need and produce – useful to climatologists on Earth as well as engineers planning future Mars missions.