Stratospheric vertical distribution

Kourtidis, K., R. Borchers, and P. Fabian, Vertical Distribution of Methyl Bromide in the Stratosphere, Geophys. Res. Lett, 25, 505-508 (1998). 

The vertical distributions of some trace gases for some regions of the stratosphere would be expected to be smooth and slowly varying. For other trace gases in other regions, extreme vertical stratification and high temporal variability would be more likely. An example of this latter case is the Antarctic... 

In my filosofie licentiat thesis of 1968 at Stockholm University I analyzed this proposal and concluded that the rate constants that had been chosen for reactions R5 and R6 could not explain the vertical distribution of ozone in the stratosphere above 25 km. Furthermore, the above choice of rate constants would also lead to unrealistically rapid loss of ozone (on a timescale of only a few days) in the troposphere (9). Anticipating a possible role of HO in tropospheric chemistry, I also briefly mentioned the potential importance of a tropospheric reaction between HO with CH4. In fact, it was soon found that reactions R5 and R6 proceed about 25 and 10 times slower, respectively, than the values given above. 

Human activity has also caused ozone changes, due to emissions of substances that deplete ozone in the stratosphere and precursors that generate ozone in the troposphere. The ozone changes, in particular in the troposphere, vary on regional scales. As discussed in WMO (1995 1999) and IPCC (1996) the radiative forcing due to ozone has a longwave as well as a shortwave component and there is a critical dependence on the vertical distribution of ozone changes. 

SPARC - Stratospheric Processes And their Role in Cliamte, Assesment of Trends in the Vertical Distribution of Ozone, edited by N. Harris, R. Hudson and C. Philips, SPARC Report No.l, WMO Ozone Research and Monitoring Project Report No. 43,1998... 

This presentation focuses on the vertical distribution of halocarbons obtained by analysis of cryogenically collected whole-air samples. The balloon-borne cryogenic samplers developed and flown by the Max-Planck-Institut fur Aeronomie (MPAE) and the Kem-forschungsanlage Jiilich (KFA) are described by Fabian [17] and Schmidt [18]. Between 1977 and 1993, a total of 33 balloon ascents have been carried out by both institutions, 28 at northern midlatitudes (southern France, 44°N), 3 at high latitudes(Kiruna, 69°N) and 2 in the tropics (Hyderabad, 17,5°N). These stratospheric data are limited to balloon altitudes, i.e. up to about 35 km. Tropospheric data were obtained from balloon samples, samples collected aboard aircraft and at ground level. 

Fabian, P. and GOmer D. (1984) The vertical distribution of halocarbons in the stratosphere, Fresenius Z. Analyt. Chem. 319,890-897. 

Drevinsky, P.J. Pecci, J. (1965) Size and vertical distributions of stratospheric radioactive aerosols. In Radioactive Fallout from Nuclear Weapons Tests, ed. A.W. Element Jr. CONF765. U.S. Dept of Commerce. N.T.I.S. Springfield, Va. 

Ground-based mm-wave emission techniques have recently provided definitive identification of HO2 in the upper stratosphere, measurements which can be directly compared with previous in situ experiments [13]. Figure 8 presents those recent spectra. These observations can be used both to cross check in situ techniques, for which two have been reported, and to extend measurements of this key free radical above the maximum altitude attainable by balloons, specifically above 45 km. We thus find a critical combination of independent techniques with highly complementary temporal and spatial coverage evolving such that the vertical distribution of a key free radical will soon be established in the scientific literature. 

There were only a few measurements of radium-226 and uranium in the ground level air. Preliminary data on the vertical distribution of radium-226 and uranium in the troposphere and stratosphere measured during periods of 3-11 years have been reported by Jaworowski and Kownacka (1976), Kownacka (1980) and Kownacka et al. (1985), and measurements of uranium in six samples of high-altitude aerosols have been reported by Krey et al. (1979). 

The fundamental innovation of the VODARO technique (vertical ozone distributions from absorption and radiation by ozone) is application of infrared observations to determination of the vertical distribution of ozone. As with most new developments, the initial discovery must be followed by a period of modifications and testing before anything like perfection and wide usage can be expected. This is a summary of one year s data applied to computations of temperature changes in the stratosphere. 

Ozone is an essential atmospheric trace substance. This gas plays an important role in the control of the radiation and heat balance of the stratosphere since it absorbs solar radiation with wavelengths shorter than about 0.3 jun. An important consequence of this absorption is that U V radiation lethal to living species does not reach the lower layers of the atmosphere. Because of the importance of atmospheric 03, its study started rather early. Junge (1963) mentions that Dobson and his associates measured total ozone (see later) beginning in the twenties by a European network consisting of six stations. Later, this network became world-wide and even the determination of the vertical distribution of 03 is now a routine measurement. Owing to these studies our knowledge of atmospheric ozone is rather substantial compared to that of other trace constituents. 

Ehhalt, D. H.,Gravenhorst,G. and Pollock, W., 1977 Vertical distribution of N20 in the troposphere and stratosphere. Proc. Joint Symposium on Atm. Ozone vol. III. Akademie der Wissenschaften der DDK, Berlin, 9-49. 

Volz, A., Ehhalt, D. H. and Cosatto, H 1978 The vertical distribution of CFM and related species in the stratosphere Pure and Appl. Geophys. lltiy 545-553. 

Bischof, W., R. Borchers, P. Fabian, and B.C. Kruger, Increased concentration and vertical distribution of carbon dioxide in the stratosphere. Nature 316, 708, 1985. 

Thus, by choosing a set of wavelengths for which the cross section au is notably different, the mole fraction of the absorbant (proportional to c) can be retrieved at different altitudes. This method is commonly used to measure the vertical distribution of ozone in the stratosphere on the global scale. The vertical resolution, however, is not better than several kilometers. 

Figure 5.19. Vertical distribution of the CO mixing ratio observed in the stratosphere. (From Zander et al., 1981.)...

In the lower stratosphere the H202 lifetime becomes longer, and the time dependent equation (5.110), must be used with a transport term V (f) (H202) added. Heterogeneous removal in clouds must also be considered in the troposphere. Figure 5.28 shows calculated vertical distributions of H, OH, H02, and H202 between 10 and 70 km altitude. 

Figure 5.53. Vertical distribution of bromine compounds in the stratosphere (24-hour-average at 30°N equinox). Adapted from McElroy (2002).

Ehhalt, D.H., L.E. Heidt, R.H. Lueb, and W. Pollock, The vertical distribution of trace gases in the stratosphere. Pageoph 113, 389, 1975a. 

Pommereau, J-P., and J. Piquard, Observations of the vertical distribution of stratospheric OCIO. Geophys Res Lett 21, 1231, 1994a. 

SPARC (Stratospheric Processes and their Role in Climate), Assessment of Trends in the vertical distribution of ozone. WMO Report No. 43, Geneva, Switzerland, 1998. 

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