Influence of the vertical motion field on ozone concentration in the stratosphere

Computations of the mean meridional motion field in the stratosphere are applied to ozone distributions to evaluate the associated ozone concentration changes. These changes are compared with those produced by photochemical and quasi-horizontal eddy processes. For the period January–April 1964 there is a cooperative action between the mean and eddy motions with mean subsidence in middle latitudes supplying ozone to be carried polawards and equatorwards by quasi-horizontal eddy processes. At low latitudes mean horizontal motions offset the eddy transport while at high latitudes mean rising motion is the offsetting term. The mean ozone flux through 50 mb, 3.5×10²⁹ molecules sec^–1, is comparable with the fluxes evaluated by other techniques.The spring maximum is thought to be due to a modulation of the energy supply to the stratospheric eddies which, in turn, force the mean motions. Longer-term changes are to be expected; for example during Ice Ages when increased tropospheric eddy activity is anticipated there should be higher total ozone.     

The concentration of molecular H2 and CH4 in the stratosphere

Stratospheric profiles of CH₄ and H₂ over eastern Texas have been derived up to 31 km altitude from air samples collected aboard a balloon and analyzed by gas chromatography. For H₂, contamination during flight and measurement presented a problem which has been resolved only recently. The earlier profiles require corrections which are rather large for the highest altitudes.The three profiles indicate an increase of the H₂ concentration in the lower stratosphere from about 0.5 p.p.m. per volume at the tropopause to about 0.8 p.p.m. at around 27 km altitude. Above that altitude the H₂ concentration decreases again. An air sample collected between 44 and 62 km by a rocket-borne cryogenic sampler had an H₂ concentration of 0.4 p.p.m.The five CH₄ profiles showed a decrease in CH₄ concentration with altitude generally with a steeper gradient directly above the tropopause and a weaker gradient at higher altitudes reaching 0.9 p.p.m. at 30 km altitude. The CH₄ concentration in the rocket sample was 0.25 p.p.m., in good agreement with the gradient obtained from the balloon samples.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

Traveling planetary waves in the stratosphere

This paper reviews the theory and observations of some traveling planetary waves in the stratosphere. Two categories of waves which appear prominently in the literature are discussed: westward propagating waves of periods in the range 3–7 days (the 5-day wave) and in the range 10–20 days (the 16-day wave). Although the observations seem to indicate that these waves are waves of the Rossby type (planetary waves), the evidence is less clear regarding (1) the question of whether these waves are forced internal waves or free (resonant) external waves, and (2) the identification of the observed waves with specific theoretical waves of the Rossby type. When recent observations are compared with theory, the evidence seems to favor the notion that the 5-day and 16-day waves of longitudinal wave number 1 may be identified, respectively, with the gravest and next gravest symmetric free Rossby modes. However, the observational evidence seems to be less clear regarding the nature of the 16-day wave than the 5-day wave.     

Instantaneous photochemical rates in the global stratosphere

Starting with the average actual distribution of ozone (Dütsch [15]) and temperature in the stratosphere, we have calculated the solar intensity as a function of wavelength and the instantaneous rates (molecules cm^–3 sec^–1) for each Chapman reaction and for each of several reactions of the oxides of nitrogen. The calculation is similar to that ofBrewer andWilson [5]. These reaction rates were calculated independently in each volume element in spherical polar coordinates defined by R=1 km from zero to 50, =5° latitude, and ø=15° longitude (thus including day and night conditions). Calculations were made for two times: summer-winter (January 15) and spring-fall (March 22). As input data we take observed solar intensities (Ackerman [1]) and observed, critically evaluated. constants for elementary chemical and photochemical reactions; no adjustable parameters are employed. (These are not photochemical equilibrium calculations.) According to the Chapman model, the instantaneous, integrated, world-wide rate of formation of ozone from sunlight is about five times faster than the rate of ozone destruction, and locally (lower tropical stratosphere) the rate of ozone formation exceeds the rate of destruction by a factors as great as 1000. The global rates of increase of ozone are more than 50 times faster thanBrewer andWilson's [5] estimate of the average annual transfer rate of ozone to the troposphere. The rate constants of the Chapman reactions are believed to be well-enough known that it is highly improbable that these discrepancies are, due to erroneous rate constants. It is concluded that something else besides neutral oxygen species is very important in stratospheric ozone photochemistry. The inclusion of a uniform concentration of the oxides of nitrogen (NO_x as, NO and NO₂) averaging 6.6×10^–9 mole fraction gives a balance between global ozone formation and destruction rates. The inclusion of a uniform mole fraction of NO_x at 28×10^–9 also gives a global balance. These calculations support the hypethesis (Crutzen [10],Johnston [24]) that the oxides of nitrogen are the most important factor in the global, natural ozone balance. Several authors have recently evaluated the natural source strength of NO_x in the stratosphere; the projected fleets of supersonic transports would constitute an artificial source of NO_x about equal to the natural value, thus promising more or less to double an active natural stratospheric ingredient.     

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.     

Relationship between the aerosol concentration in the stratosphere and ionization according to the data on conductivity and nitrate content of Greenland ice

This paper studies the data on the conductivity and concentration of nitrates (ions) in an ice core from central Greenland obtained with high time resolution. The performed analysis indicates that the abrupt increase in the concentration of sulfate aerosols in the stratosphere due to additional ionization resulted from precipitation of solar cosmic ray energetic particles is one of the main factors that cause simultaneous origination of powerful peaks in the nitrate conductivity and concentration. Thus, coincidences of peaks in both studied paleoseries are manifestations of the effect that has been experimentally registered with lidar and satellite equipment for the last 25 years. This demonstrates that the relationship between the aerosol concentration and the ionization rate in the stratosphere is real and makes it possible to expand the interval where this relationship exists to more than 200 years. The possible physical mechanisms of the observed phenomenon are discussed.     

Vertical profiles of condensation nuclei in the stratosphere

An automatic condensation nuclei counter was developed for the concentration range of about 1 to 400 particles per cubic centimeter. After expansion, the water droplets are photographed when they are still suspended in the air so that the counter can be considered an absolute one. The volume in which the droplets are counted is determined by the size of the picture of the droplets as a function of their distance from the focal plane. To eliminate any effect of decreasing pressure with altitude, the cloud chamber is filled with clean air prior to expansion to about half an atmosphere above ambient pressure. This counter was used to obtain vertical profiles of condensation nuclei up to altitudes of 27 km with high altitude balloons. A total of seven profiles was obtained over a period of about one year at 47° N over the United States. Because of the restrictions in the range of the meter no data could be obtained below 5 km. The profiles show the following main features:

1. 1.
   Although there are pronounced fluctuations in the individual flights the average nuclei concentration of 200 to 300/cm³ remains fairly constant from 5 km to the tropopause.     
   
   

The ineffectiveness of Joule heating in the stratosphere

Several papers have recently invoked Joule heating in the stratosphere, generated from electric currents induced by solar wind interactions with Earth, as possibly playing a significant role in warming the polar stratosphere. This commentary assesses the accuracy of that contention and demonstrates that in situ Joule heating can take no significant part in warming the stratosphere, and thus cannot be used to suggest a link between stratospheric temperatures and solar activity.     

Ozone and temperature change in the winter stratosphere

Summary In an experiment to study the correlation between temperature and ozone in the disturbed winter atmosphere, two rocket-borne ozonesondes were flown during a time in which the temperature structure, in the stratosphere and lower mesosphere changed at certain altitudes from the previous day. The resulting ozone and temperature distribution, as compared to distribution on the control day at the end of the winter season, showed variations during the time the atmosphere was disturbed. These variations may be explained by considering the temperature-dependence of reaction rates for an oxygen atmosphere.     

On the behavior of nitrogen oxides in the stratosphere

A summary is presented of the relative importance of the principal aeronomic processes determining the vertical distribution of NO–NO₂ in the stratosphere. Formation and destruction of nitric oxide are considered with transport processes for steady-state conditions. Estimates of the vertical distribution of NO _x are made for extreme conditions of the eddy diffusion coefficient. It is pointed out that NO is determined by the values which are adopted for its photodissociation coefficient which is related to the absorption of solar radiation in the Schumann-Runge bands of molecular oxygen.     

The role of the stratosphere in climate change

A variety of climate perturbations have the potential to alter the thermodynamic and dynamical characteristics of the middle atmosphere, which may then affect tropospheric climate. Increased thermal emission from rising stratospheric CO₂ levels and scattering of solar radiation from stratospheric volcanic aerosols have a direct impact on surface temperatures, while variations in stratospheric water vapor and ozone can affect tropospheric temperatures. Observations and modeling experiments suggest that these perturbations, as well as solar irradiance variations operating through the stratosphere, may affect tropospheric dynamics, such as planetary wave amplitudes and Hadley cell intensity. In addition, climate changes will probably alter tropospheric/stratospheric exchange, with the potential for modifying trace gas distributions and climate forcing. These issues are reviewed in the light of the incorporation of middle atmosphere studies into IGBP.     

Ozone and temperature changes in the lower stratosphere

The vertical profiles of ozone and temperature from a series of balloon soundings at Delhi (28°N), Poona (18°N) and Trivandrum (8°N) were studied with synoptic meteorological data. While both ozone and temperature profiles show similar variations over all three stations, ozone maxima being always associated with thermally stable layers, the variations are most pronounced over Delhi, particularly in winter and in early spring when a series of western disturbances pass over north India. Both ozone and temperature profiles over Delhi show a layer structure characterized by a series of maxima and minima in both the vertical distribution of ozone and temperature and these are most pronounced in the lower stratosphere. These variations are associated with the influx of ozone-rich middle latitude stratospheric air over Delhi replacing subtropical air.     

Volcanoes, the stratosphere, and climate

A list of volcanic eruption plumes observed to ascend into or near the stratosphere since 1883 shows that the volcanoes divide readily into two groups, one at low and one at higher latitudes. A model for the rise of a buoyant volcanic plume rise as applied to volcanic eruptions is corrected for realistic temperature profiles and for the finite vertical extent of the resultant debris clouds. The utility of the model can be questioned, however, owing to the highly uncertain and variable nature of the efficiency of use of heat energy of buoyant rise. The observed correlation of stratospheric plumes with climatic effects indicates that those plumes nearer the equator have the largest impact on surface temperatures. Analysis of the observations also suggests that injection of debris into the stratosphere is more important in determining the effect on climate than either the total volcanic explosivity of the eruption or the actual height reached within the stratosphere.     

Atmospheric ozone and the movement of the air in the stratosphere

Using over 2200 ozonesonde ascents, published byHering andBorden [1]–[5] and byDütsch et al. [6], [7], the average vertical distribution of the ozone mixing ratio is found for different latitudes and for different seasons up to a height of 30 km. The method by which the ozone formed at great heights in low latitudes becomes concentrated in the lower stratosphere of high latitudes is discussed, and the meridional circulation theory is strongly suggested.Oxford, May 1972.     

Ozone variation in the lower stratosphere and its mechanism

Seasonal variations of ozone are studied by taking into consideration both photochemical and dynamical processes. Assuming that the seasonal variations of total ozone amounts are linear combinations of photochemical equilibrium variations and those due to atmospheric motions, the observed variations of the total ozone amount seem reasonably to be explained.The concept mentioned above implies that the time scale of ozone might be rather short in the lower stratosphere. The order of the half restoration time was estimated to be 10 to 10² days in the lower stratosphere. Thus the estimated time scale of ozone must be somewhat longer than that of the temperature in the lower stratosphere, of which variation usually shows its maximum in the midwinter in middle latitudes, while that of ozone shows its maximum in the late winter or early spring. As the maximum values of both quantities would appear in the early summer without air motions, the similarity in the phase differences of temperature and ozone suggests the validity of the concept of this paper.     

Nonlinear behavior on an ozone photochemical system in the stratosphere

A nonlinear box system describing ozone photochemistry in the stratosphere is presented. Influences of pollutants, such as odd chlorine (Cl_x) and odd nitrogen (NO_x) discharged by human activities, on photochemical states of the system are investigated in detail. The results show that the solutions of the box system constitute a ‘cusp’ catastrophe manifold in the state-parameter space. An increase of about 30% for Cl_x source strength or a decrease of about 30% for NO_x source strength from their current level may lead to catastrophic transition and results in a reduction of ozone concentration about 50 times. Project supported by the National Natural Science Foundation of China and Laboratory for Aeronomy and Global Environmental Observation of IAP.     

Mean meridional circulations of the stratosphere and mesosphere

Observations from the Nimbus 6 pressure modulator radiometer (PMR) have been used to estimate monthly mean planetary wave fluxes of heat and momentum in the stratosphere and mesosphere. While the eddy heat fluxes play an important role in the mean meridional circulation of the winter stratosphere they are shown to be less important in the upper mesosphere. Incorporation of the observed momentum fluxes into the Oxford two-dimensional circulation model has shown that they are incapable of providing the momentum transport necessary to balance the zonal flow accelerations induced by the mean meridional motion. Other unspecified transfer processes represented by Rayleigh frictional damping of the zonal fow are shown to dominate. In contrast the observed fluxes in the stratosphere achieve the necessary redistribution of momentum. Moreover their interannual variability profoundly influences the stratospheric circulation, as demonstrated in the model by the use of two different annual sets of observed momentum fluxes. The desirability of calculating the planetary wave behaviour within the model is indicated.     

Zonal and meridional air currents in the stratosphere over Europe

Wind observations in the stratosphere above the British isles are treated statistically, with special regard to the variations of zonal and meridional wind components with height and during the year.

---

Zusammenfassung Windbeobachtungen aus der Stratosphäre über den Britischen Inseln sind statistisch bearbeitet worden, wobei das Hauptgewicht darauf gelegt wurde, das Verhalten der zonalen und meridionalen Windkomponente im Jahresgang und als Funktion der Höhe zu beschreiben und diskutieren.

     

Microwave measurements of the ozone content in winter arctic stratosphere

As a result of the long-term observations lead in region of Kola Peninsula, connection between character of variations of the ozone content in a stratosphere of Arctic regions and behavior and structure of a winter polar vortex is established. During winter seasons with well developed cyclone and duration of stable existence not less than 1.5–2 months were observed extremely low ozone number density at heights 20–25 km connected, apparently, with its chemical destruction. On the other hand, during disturbances of the vortex, accompanied strong stratospheric warming, was registered almost double increase of ozone amount in a high-altitude interval from 20 up to 40 km. Comparison of results of ground-based microwave monitoring of an ozone layer to data of the satellite instrument EOS MLS installed on satellite AURA is lead. In most cases comparison has shown satisfactory within the limits of an error of measurements coincidence of results. However in conditions of atmospheric disturbances when arose significant spatial heterogeneity, the discrepancy of results of comparison was marked. The possible reasons which cause the detected disagreement in results are discussed.