Stratospheric flight

H. 6. Booker, et al., Environmental Impact of Stratospheric Flight, National Academy of Sciences, Washington D. C., 1975. 

The stability of these species and their relatively long photochemical lifetimes by day (4 hours for HC N02 and CIONO2) means that their inclusion in atmospheric models reduces the predicted rates of ozone destruction. As Fig. 4 shows the inclusion of such species in atmospheric models has led to considerable changes over the last few years in the predictions for future ozone depletion by halocaibons and by nitrogen oxides from stratospheric flight... 

The discovery of ozone holes over Antarctica in the mid-1980s was strong observational evidence to support the Rowland and Molina hypothesis. The atmosphere over the south pole is complex because of the long periods of total darkness and sunlight and the presence of a polar vortex and polar stratospheric clouds. However, researchers have found evidence to support the role of CIO in the rapid depletion of stratospheric ozone over the south pole. Figure 11-3 shows the profile of ozone and CIO measured at an altitude of 18 km on an aircraft flight from southern Chile toward the south pole on September 21, 1987. One month earlier the ozone levels were fairly uniform around 2 ppm (vol). 

The ozone balance in the stratosphere is determined through complex interactions of solar radiation, meteorological movements within the stratosphere, transport to and from the troposphere, and the concentration of species based on elements other than oxygen that enter the stratosphere by natural or artificial means (such as flight of aircraft). 

It is difficult to envision that balloon-borne techniques will be able to satisfy the demand for more complex and frequent measurements. Therefore it is critical for maximizing the scientific return of balloon-borne flights to include simultaneous measurements of the right mix of species and photolysis rates. In the absence of frequent balloon-borne measurements it is nonetheless very gratifying to have achieved the coalescence of results by independent techniques as a zero-order substitute for intercomparisons. A possible direction for future stratospheric research with a new platform, remotely piloted aircraft, that alleviates some disadvantages of balloon-borne platforms is discussed in the last section of this chapter. 

NOx emissions from subsonic aircraft flying in the troposphere and the lowermost stratosphere lead to a significant increase in ozone in the upper troposphere. Emissions of NOx and H20 from supersonic aircraft cruising in the stratosphere are calculated to decrease the column abundance of O3. The effects of aircraft emissions are found to be strongly dependent on flight altitudes and on assumed emission indices for NOx. 

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