Ozone from aircraft measurements

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). 

For any event to be accurately recorded, it must persist for the pulse time of the instrument. This time is equal either to the rise time or to the time to 100% response, depending on the design of the instrument. For accurate data from aircraft sampling plumes, for example, it is necessary to obtain rise times of a few seconds or less. This is a very fast response for an analyzer and has only recently become possible for ozone measurements. 

Proffitt, M. H J. J. Margitan, K. K. Kelly, M. Loewenstein, J. R. Podolske, and K. R. Chan, Ozone Loss in the Arctic Polar Vortex Inferred from High-Altitude Aircraft Measurements, Nature, 347, 31-36 (1990). 

Continuous Measurement Methods for Trace Cases and Aerosols. Ozone. Three basic types of ozone instruments have been used in aircraft the ultraviolet photometric method and two chemiluminescent techniques measuring, respectively, light emitted from the reaction of 03 with ethylene and light emitted from the reaction of 03 with NO. Ultraviolet absorption photometry is one of the preferred methods for measuring 03 from aircraft because of the stability and reliability of commercially available instruments. The method is specific for 03 provided there are no immediate... 

Fig 3. Background ozone values over Greece. Upper panel Measurements of tropospheric ozone from 0 to 12 km altitude with ozonesonde (Thessaloniki) and the FALCON aircraft (Athens-Thessaloniki flight path). Lower panel Mean diurnal variation of ground ozone during PAURI at three sites. 

Case Study - A practical example of the dependence of ozone production on NO - An example of the experimental determination of these relationships is shown in Figure 13, a comparison of observed ozone production rates ( (03)) and concentrations of HO2 and OH from the NASA SONEX mission plotted as a function of NO. The data were taken from a suite of aircraft measurements between 8 and 12 km altitude at latitudes between 40 and 60°N. The model data suggest that (03) becomes independent of NO above 70 pptv and the turn-over point into a NO -saturated regime occurs at about 300 pptv. The bulk of the experimental observation below [NOJ < 300... 

The earliest observations of the chemical composition of the middle atmosphere were performed primarily by balloon-borne (stratosphere) and rocket-borne (mesosphere) instrumentation. In recent decades, however, systematic observations have been made by space-borne sensors, and information on chemical processes in the upper troposphere and lower stratosphere has been provided through chemical measurements made from aircraft platforms (e.g., from high-altitude aircraft such as the ER-2, the WB-57 and the Geofysika). Measurements from ground stations, combined with satellite observations, have provided accurate estimates of long-term ozone trends in the different regions of the world. 

Falconer, P. D., R. Pratt, and V. A. Mohnen (1978). The transport cycle of atmospheric ozone and its measurements from aircraft and at the earth s surface. In Man s Impact on the Troposphere, Lectures in Tropospheric Chemistry (J. S. Levine and D. R. Schryer, eds.), pp. 109-147. NASA Reference Publication 1022. National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia. 

Pearson, R. Jr., and Stedman, D. H. (1980) Instrumentation for fast-response ozone measurements from aircraft, Atmos. Technol. 12, 51-55. 

Fig. 2.84 Historical data on the dependence of ozone from altitude. Data from Konstantin-ova-Schlesinger (1937a, 1937b, 1938) from the Soviet Union in the 1930s years (Moscow 100 m, Elbrus 2200 m and 4300 m, aircraft measurements 9620 m, 13 000 m and 1400 m) Swiss date (Genf 200 m, Zermatt 1650 m, Rochers de Naye 2045 m and Gornergrat 3200 m) from Gmelin (1943) and Staehelin et al. (1994).

In the late 1980s, aircraft were flown into the austral and boreal polar stratosphere to investigate the depletion of lower stratospheric ozone at high latitudes. The aircraft measurements revealed that stratospheric air pole-ward of the wintertime zonal-mean jet core is highly isolated from midlatitude air during winter. This isolation, combined with the cold temperatures and subsequent polar stratospheric cloud appearance, allows the chemical environment to become highly perturbed. Stratospheric temperatures below about 195 K at 20 km are required for... 

Fig. 11-3. Stratospheric ozone and CIO concentrations at an altitude of 18 km measured by aircraft flying south over Antarctica on September 27,1987. The dramatic decrease in ozone at a latitude of 71 degrees is attributed to the role of CIO in catalytic destruction of ozone. Adapted from Anderson et al. (13).

Dias-Lalcaca, P., D. Brunner, W. Imfeld, W. Moser, and J. Staehelin, An Automated System for the Measurement of Nitrogen Oxides and Ozone Concentrations from a Passenger Aircraft Instrumentation and First Results of the NOXAR Project, Environ. Sci Technol., 32, 3228-3236 (1998). 

Figure 24-19 Partial gas chromatogram for which an electron capture detector was used to measure halogenated compounds in air collected by an aircraft at an altitude of 800 m at a location 1 400 km south of New Zealand in 1995. /From F. S. Howland, Stratospheric Ozone Depletion by Chloroftuorocarbons." Angtyw Chem. Int. Bd. Engl. 1996,35, 1787]...

Figure 1. This graph shows the rapid variation of CIO and 03 as the edge of the chemically perturbed region in the Antarctic polar vortex is penetrated by the National Aeronautics and Space Administration (NASA) ER-2 high-altitude aircraft over the Palmer Peninsula of Antarctica on September 16, 1987 (5). It is one of a series of 12 snapshots, or individual flights, during the Airborne Antarctic Ozone Experiment (AAOE) that show the development of an anticorrelation between CIO and 03 that began as a correlation in mid-August. When these two measurements are combined with all the others from the ER-2 aircraft, the total data set provides a provocative picture of how such chemistry occurs and what it is capable of doing to ozone.

A large number of observations, both remote and in situ, confirm this qualitative picture of the loss of ozone over Antarctica. The in situ data have come from instruments carried on small balloons and the NASA ER-2 high-altitude aircraft. Small-balloon measurements are of particle distributions and sizes, ozone, and water vapor (23, 33). ER-2 measurements, listed in Table I, are of particle size and composition atmospheric parameters such as temperature, pressure, lapse rate, and winds and trace gas abundances of 03, N20, NOy or NO, CIO and BrO, and stable gases, including CH4, chlorofluorocarbons, halons, and others (34-45). 

The Airborne Submillimeter SIS Radiometer (ASUR), operated on-board the German research aircraft FALCON, measures thermal emission lines of stratospheric trace gases at submillimeter wavelength. Measurement campaigns with respect to ozone depletion in the Arctic winter stratosphere were carried out in yearly intervals from 1992-97 to investigate the distributions of the radical chlorine monoxide (CIO), the reservoir species hydrochloric acid (HC1), the chemically inert tracer nitrous oxide (N20), and ozone (O3). The high sensitivity of the receiver allowed to take spatially well resolved measurements inside, at the edge, and outside of the Arctic polar vortex. This paper focuses on the results obtained for CIO from... 

International Arctic Ozone Study, which runs campaigns in winter every year. NASA researchers and many scientists from the U.S.A., the E.U., Canada, Iceland, Japan, Norway, Poland, Russia, and Switzerland work together in winter to measure ozone and other atmospheric gases. The scientists use aircraft, large and small balloons, ground-based instruments, and satellites. 

It follows from this discussion that the inadvertent ozone depletion in the past and at present is not expected to be measurable. This conclusion is supported by observational data on total ozone showing a net increase during recent years. This is confirmed by observations carried out at various places on the Earth s surface. Thus, according to Komhyr et al. (1971) between 1958 and 1970 the rate of this increase has been as large as several percent per decade (see Fig. 57). It is to be noted in this respect that Mastenbrock (1971) found that the stratospheric water vapour burden over the U.S.A. also increased significantly in recent years and this was attributed to the water vapour emission of supersonic aircraft. In Subsection 3.4.3 we mentioned that free radicals formed from water vapour can play a certain role in... 

The solar spectrum has been the subject of numerous rocket experiments undertaken since the 1940s. The first spectrum measured above the ozone layer by a V-2 rocket dates from October 1946 (Baum et al, 1946), and not until the 1950s was a solar spectrum observed from an altitude of 100 km (Johnson et al, 1952). Today the solar irradiance is routinely observed by spectrometers on board balloons, aircraft, or spacecraft. During the 1990s, for example, the solar UY flux was measured almost continuously between 120 and 400 nm by the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) and the Solar/Stellar Irradiance Comparison Experiment (SOLSTICE), both on board the... 

---