Stratosphere function

Ozone has received increased attention for its occurrence and function in the Earth s atmosphere.For example the decreasing ozone concentration in the stratospheric ozone layer, becoming most obvious with the Antarctic ozone hole. 

This process does not lead to net ozone depletion because it is rapidly followed by reaction 2, which regenerates the ozone. Reactions 2 and 3 have, however, another important function, namely the absorption of solar energy as a result, the temperature increases with altitude, and this inverted temperature profile gives rise to the stratosphere (see Figure 1). In the lower layer, the troposphere, the temperature decreases with altitude and vertical mixing occurs on a relatively short time scale. In contrast, the stratosphere is very stable towards vertical mixing because of its inverted temperature profile. 

The turnover time of water vapor in the atmosphere obviously is a function of latitude and altitude. In the equatorial regions, its turnover time in the atmosphere is a few days, while water in the stratosphere has a turnover time of one year or more. Table 7-1 Qunge, 1963) provides an estimate of the average residence time for water vapor for various latitude ranges in the troposphere. Given this simple picture of vertical structure, motion, transport, and diffusion, we can proceed to examine the behavior of... 

In principle any pre-functionalized resin can be formed into a plug and the monoliths show good solvent resistance except to e.g. hot toluene or xylene. The size of each plug makes them easily manipulated by a robot and use in scavenging situations seems very attractive. Some applicahons have already been reported [56] and the monoliths will be made available as StratoSphere Plugs via Polymer Laboratories (Church Stretton, UK). 

Many addition reactions such as the OH-SOz reaction are in the falloff region between second and third order in the range of total pressures encountered from the troposphere through the stratosphere. Troe and co-workers have carried out extensive theoretical studies of addition reactions and their reverse unimolecular decompositions as a function of pressure (e.g., see Troe, 1979, 1983). In this work they have developed expressions for the rate constants in the falloff region these are now most commonly used to derive the... 

FIGURE 12.46 Model-calculated cumulative loss of ozone from August 1 to the day of maximum ozone depletion as a function of stratospheric bromine ([Cl,.] = 12.5 ppbv, [NO,.] = 2 ppb, 70°S at an altitude corresponding to 50 mbar total pressure in these calculations) (adapted from Danilin et al., 1996). 

Figure 13.1 also shows the estimated equivalent effective stratospheric chlorine content as a function of year under the Copenhagen Amendments. Chlorine is expected to peak around the year 2000 and then decrease. As discussed by Holmes and Ellis (1996), non-compliance and allowed exemptions could lead to a much slower decline than projected in Fig. 13.1. 

Grams, G. W., 1981. In-situ measurements of scattering phase functions of stratospheric aerosol particles in Alaska during July 1979, Geophys. Res. Lett., 8, 13-14. 

From the data of Figure 1 and the mean altitude of the tropopause as a function of latitude the computation of the tropospheric inventory of 14C is straightforward. Although the stratosphere is more difficult to... 

From Table VIII—1B and JQj of Fig. VIII-7, re,(03) is calculated as a function of altitude. This relationship is shown in Fig. VIII—9. The equilibrium time scale near the top of the stratosphere is about a day, while below 15 km Te (Oj) more than a year and downward physical transport processes of 03 become important. 

The topographic distribulion of fallout is divided into three categories called (I) local (or close-in) (2) tropospheric (or intermediate) and 3i stratospheric or worldwide) fallout. No distinct boundaries exist between these categories. The distinction between local and tropospheric fallout is a function of dislance from source to point of deposit The primary dislinclion between tropospheric and stratospheric fallout is the place of injection of the dehris into the atmosphere, above or below the iropopause. Whether the radioactive debris from a nuclear weapon becomes tropospheric or stratospheric fallout depends on yield, height, and lalilude of burst (the height of the iropopause is a function of latitude). 

ORM assumes that the atmosphere is in local thermodynamic equilibrium this means that the temperature of the Boltzmann distribution is equal to the kinetic temperature and that the source function in Eq. (4) is equal to the Planck function at the local kinetic temperature. This LTE model is expected to be valid at the lower altitudes where kinetic collisions are frequent. In the stratosphere and mesosphere excitation mechanisms such as photochemical processes and solar pumping, combined with the lower collision relaxation rates make possible that many of the vibrational levels of atmospheric constituents responsible for infrared emissions have excitation temperatures which differ from the local kinetic temperature. It has been found [18] that many C02 bands are strongly affected by non-LTE. However, since the handling of Non-LTE would severely increase the retrieval computing time, it was decided to select only microwindows that are in thermodynamic equilibrium to avoid Non-LTE calculations in the forward model. 

As noted above, the LUT algorithm assumes a unimodal lognormal functional form to describe stratospheric aerosols. This approximation is well suited for most non-volcanic stratospheric aerosols as shown by Pueschel et al. [7] and Yue et al. [8]. Volcanic size distributions, however, are typically bi- or trimodal. This raises the question of whether the assumption of unimodality in the LUT can introduce bias into retrieved values of Rt//, S and V. Russell et al. [1] have shown that retrieved unimodal distributions accurately describe the second, larger mode of several measured bimodal size distributions, but fail to account for the smaller particles in the first mode. The smaller particles, which contribute little to the measured extinction spectra, are not accounted for in the LUT retrievals. Unless this bias is accounted for, the values of Rtff retrieved under the assumption of a unimodal distribution will be overestimated. 

The main goal of this research is to construct a global, vertically-resolved data set of several stratospheric aerosol parameters retrieved by the LUT algorithm. This section presents examples of LUT retrievals of Rtff, S, V and [Pg.356]

Bekorukov V.l. (1967) Seasonal changes of heating function of the stratosphere, Trydi of Central Aerological Observatoiy, vipusk 76, p.19-26 /in Russian/... 

---