Ozone distribution

The horizontal dispersion of a plume has been modeled by the use of expanding cells well mixed vertically, with the chemistry calculated for each cell (31). The resulting simulation of transformation of NO to NO2 in a power plant plume by infusion of atmospheric ozone is a peaked distribution of NO2 that resembles a plume of the primary pollutants, SO2 and NO. The ozone distribution shows depletion across the plume, with maximum depletion in the center at 20 min travel time from the source, but relatively uniform ozone concentrations back to initial levels at travel distances 1 h from the source. 

Oltmans, S. J., and W. D. Komhyr, Surface Ozone Distributions and Variations from 1973-1984 Measurements at the NOAA Geophysical Monitoring for Climatic Change Baseline Observatories, J. Geophys. Res., 91, 5229-5236 (1986). 

Munro, R., R. Siddans, W. J. Reburn, and B. J. Kerridge, Direct Measurement of Tropospheric Ozone Distributions from Space, Nature, 392, 168-171 (1998). 

Lu, R., and R. P. Turco, Ozone Distributions over the Los Angeles Basin Three-Dimensional Simulations with the Smog Model, Atmos. Environ., 30, 4155-4176 (1996). 

The model tropopause is defined by a PV level of 3.5 pvu poleward of 20° latitude, and by a -2 K km 1 temperature lapse rate equatorward of 20° latitude. Consequently, in this study the troposphere is defined as the volume between the surface and the simulated tropopause. Because the model does not consider typical stratospheric chemical reactions explicitly, ozone concentrations are prescribed from 1-2 levels above the model tropopause up to the top of the model domain at 10 hPa. In both hemispheres we apply monthly and zonally averaged distributions from a 2D stratospheric chemistry model [31]. In the present version of the model, we use the simulated PV and the regression analysis of the MOZAIC data (Section 2) to prescribe ozone in the NH extratropical lower stratosphere, which improves the representation of ozone distributions influenced by synoptic scale disturbances [32, 33]. Furthermore, the present model contains updated reaction rates and photodissociation data [34]. 

Figure 2. Comparison of simulated ozone (ppbv) and potential vorticity (pvu) with MOZAIC data for the flight from Frankfurt (Germany) to New York (USA) on March 15, 1996 (a) simulated horizontal ozone distribution at approximately 10 km altitude (03 in ppbv) solid line denotes the flight path (b) simulated vertical ozone distribution along the flight path solid line denotes the model tropopause, dashed line denotes the flight altitude (c) ECMWF (dotted) and modeled (solid line) potential vorticity along the flight path (d) observed (dotted) and modeled (solid line) ozone concentrations along the flight path.

We have addressed several aspects of STE of ozone and the impact on tropospheric ozone levels. Using ozone observations in the upper troposphere and lower stratosphere from MOZAIC, we have examined the rdation between ozone and PV in the lower stratosphere. A distinct seasonality in the ratio between ozone and PV is evident, with a maximum in spring and minimum in fall associated with the seasonality of downward transport in the meridional circulation and of the ozone concentrations in the lower stratosphere. The ozone-PV ratio is applied in our tropospheric chemistry-climate model to improve the boundary conditions for ozone above the tropopause, to improve the representativity of simulated ozone distributions near synoptic disturbances and realistically simulate cross-tropopause ozone transports. It is expected that the results will further improve when the model is applied in a finer horizontal and vertical resolution. 

Since the emissions of CO and CH4 from aircraft have little impact on the atmospheric composition compared to the impact from NOx emitted from aircraft, the result of NOx emission from aircraft is to enhance NOx distribution and thereby the ozone distribution through reactions R1 - R3, and to reduce the CO and CH4 distribution through the interaction with OH through reactions R4 and R6 respectively. NOx emissions from aircraft will therefore enhance the abundance of one important greenhouse gas (03) and reduce the abundance of another (CH4). A key point in studies of the climate impact of NOx emission from aircraft is therefore to determine these opposite effects. 

Wauben, W.M.F., J.P.F. Fortuin, P.F.J. van Velthoven, and H. Kelder, 1997b Comparison of modeled ozone distributions with sonde and satellite observations, J. Geophys. Res. (in press). 

A few studies of the impacts of changes in tropospheric ozone have been based on general circulation models (GCMs Hansen et ah, 1997b, Chalita et ah, 1996). In these studies ozone distributions were taken from CTMs, namely the MOGUNT1A and the IMAGES 3D CTM respectively. 

Large uncertainties remain due to insufficient knowledge about the ozone distributions in the unperturbed as well as the present atmosphere. The ozone distribution is particularly uncertain in the tropics. The best estimate of WMO (1999) of global-mean radiative forcing since the mid-1800s is 0.35 Wm 2 with an uncertainty range +0.15 Wm 2, bracketing the results from a majority of studies. 

The earliest measurement utilising the BUV technique was undertaken by Rawcliffe and Eliot (1966) using a photometer observing at 284 nm. Ozone distributions were determined utilising measurements from the USSR COSMOS satellites, which... 

Iozenas, V.A. et al. (1969b) An investigation of the planetary ozone distribution from satellite measurements of ultraviolet spectra. Izvestiya Akademii Nauk SSSR Fizika Atmosfery I Okeana 5 219-233. 

Munro, R R. Siddams, W.J. Rebum and B.J. Kerridge (1998) Direct measurement of tropospheric ozone distributions from space. Nature 392 168-171. 

Singer, S.F. and R.C. Wentworth (1957) A method for the determination of die vertical ozone distribution of ozone distribution from a satellite. Journal of Geophysical Research 62 299-308. 

The aim of this study is to describe the dynamical consequences (e.g. thermal response) of the middle atmosphere, which are directly related to the ozone distribution by using a mechanistic three-dimensional model of the middle atmosphere and the 3-D GEOS ozone data. 

On the basis of the OEOS ozone data, two model experiments were carried out experiment "A" - with 3-D ozone and experiment B - with zonal averaged ozone distribution. The model calculations started at the first day of the GEOS ozone data... 

Bojkov R. D., (1968) Planeta/y Features of total and vertical Ozone Distribution during 1QSY, IDOJARAS... 

Figure 28 Antarctic and Artie ozone distributions in the SH and NH spring periods.

Figure 4.3 shows the ozone distribution within the stratosphere, before 1984. (The problemetic ozone hole is dealt with in Chapter 8). 

FIGURE 8.2. Ozone distribution over Antarctica in different years. 

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