Ozone vertical profile atmosphere

FIGURE 12.5 Model-calculated ozone vertical profiles for a Chapman or Ox model, with only 02, O, and O, as reactive species and the reference atmosphere chosen to be typical of 1960 conditions (adapted from Kinnison et al., 1988). 

In the real atmosphere horizontal motions along latitude and longitude must also be taken into consideration. Thus, the ozone concentration profile should show a significant derivation near the tropopause due to the downward transport of 03 from the expected profile without vertical eddy diffusion. 

The monthly mean ozone from the Dobson time series (1957-1986) of Vigna di Valle (50 km apart from Rome) and from TOMS (Total Ozone Mapping Spectrometer) satellite data (1979-1991) version 6 are assumed as climatological frames of reference for Rome and Ispra, respectively. Aerosol optical depths at 550 nm are estimated by means of sunphotometry. Data from the two meteorological stations of Rome and Milan airports are used to describe the atmospheric conditions. Standard vertical profiles of pressure, temperature, relative humidity and ozone density are selected. 

Knapska, D., Schmid, U., Jebsen, C., Kulessa, G., Rudolph, J. and Penkett S.A. (1985) Vertical profiles of chlorinated source gases in the midlatitude statrosphere, in C.S. Zerefos and A. Ghazi (eds.), Atmospheric Ozone, Reidel, Dordrecht, pp. 117-121. 

The numerical technique for the determination of vertical profile information was also studied for the determination of total ozone in the atmosphere by NASA (Dave and Mateer, 1967 Mateer et al., 1971). The development of this retrieval technique has continued up to the present (Bhartia et al., 1996). 

The Backscatter Ultraviolet atmospheric ozone experiment (BUV) was the first of a series of instruments made by NASA and later NOAA, which has successfully made long-term measurements of the vertical profile and total amount of ozone (Heath et al., 1973) (Table 1). BUV was launched aboard the Nimbus 4 satellite into a circular polar orbit at an altitude of 1100 km. This orbit is sun-synchronous and the satellite crosses the equator in an ascending mode every 107 minutes close to local noon. 

The second stage realizes a two-step procedure that re-calculates the ozone concentration over the whole space S = (tp, A, z) (, A)e l 0atmospheric boundary layer (zH 70 km), whose consideration is important in estimating the state of the regional ozonosphere. These two steps correspond to the vertical and horizontal constituents of atmospheric motion. This division is made for convenience, so that the user of the expert system can choose a synoptic scenario. According to the available estimates (Karol, 2000 Kraabol et al., 2000 Meijer and Velthoven, 1997), the processes involved in vertical mixing prevail in the dynamics of ozone concentration. It is here that, due to uncertain estimates of Dz, there are serious errors in model calculations. Therefore the units CCAB, MFDO, and MPTO (see Table 4.9) provide the user with the principal possibility to choose various approximations of the vertical profile of the eddy diffusion coefficient (Dz). 

Solar Radiation. Of all the factors which collectively determine the amount and spectral distribution of the radiation entering a surface layer of the atmosphere, the best established appear to be the spectral irradiance outside the atmosphere and the attenuation by molecular scattering. The absorption coefficients of ozone are well established, but no easy method exists for determining the amount of ozone in a vertical profile of the atmosphere at a given time. The measurement of the particulate content of the atmosphere and its correlation with atmospheric transmission is a field in which much remains to be accomplished. Surprisingly few data exist on the spectral distribution of sky radiation and its variation with solar elevation and atmospheric conditions. The effect of clouds is of secondary importance, as intense smog generally occurs under a clear sky. 

By means of equation [3.17], the equilibrium vertical profile of the ozone concentration can be calculated. Thus, [02] on the right-hand side is known for various altitudes and k can be calculated for different temperatures.11 The greatest problem is the determination of /, and f2 as a function of altitude. The values of these latter parameters depend on the absorption of radiation, which varies in a complex way as solar radiation penetrates into the atmosphere. Theoretically /, and J2 are calculated by the following two equations ... 

The vertical profile of ozone expressed in nanobars as a function of atmospheric pressure (ordinate millibar) for different NO,(ppb)and H20 (ppm) mixing ratios (Diitsch, 1973). (By courtesy of Birkhauser... 

Chen et al., 1997). Perhaps most important is the ability of models to simulate the overall shapes of the vertical profiles of the responses obtained in both ozone and temperature, since these in turn support the calculation of the penetration of radiation into the atmosphere and hence provide a key test of theory. 

Another major feature of the vertical thermal structure of the atmosphere is due to the presence of ozone (O3) in the stratosphere. This layer is caused by photochemical reactions involving oxygen. The absorption of solar UV radiation by O3 causes the temperature in the stratosphere and mesosphere to be much higher than expected from an extension of the adiabatic temperature profile in the troposphere (see Fig. 10-1). 

Fig. 8.1 Comparison of vertical ozone profiles caleulated by the pure oxygen atmosphere themy (Chapman mechanism) and by observation (Adapted from Shrmazaki et al. 1987)...

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