Messung der Verteilung flugzeugbedingter Spurengase in der oberen Troposphaere und unteren Stratosphaere Abschlussbericht

During the summer and winter 1994, the research aircraft Falcon of the German Aerospace Research Establishment (DLR) Oberpfaffenhofen flew a total of 8 missions in the region of the transatlantic main flight corridor off the shores of Great Britain and Ireland. Besides the meteorological parameters temperature, humidity and wind (2-d), the measurements covered the mixing ratios of 0_3, NO_2, NO_y, CO, CO_2 and some volatile hydrocarbons (VOC) as well as the photolyserates of ozone. Cruising flight in this region occurs in clean air masses from the middle and upper troposphere, partly in air masses with marked stratospheric character and partly even in convection carried air masses from the lower troposphere. In most cases a very heterogeneous composition and mixing of different types of air masses was observed. Against this heterogeneous background individual exhaust plumes from airliners were detected during all flights. These trails are characterized as enrichments of the nitrogen oxide concentrations. Other trace gas measurements were not able to identify the trails. As a result of wind transportation the trails occur isolated in most cases. In few cases, when the wind vector ran parallel to the flight routes, the influence of air traffic on the nitrogen oxide concentrations was identified even in higher regions of 30 km horizontal extension or 200 m vertical extension. The results were interpreted by means of a photochemical box model specifically developed for this purpose. The model predictions of the ratios NO/NO_y and NO_x/NO_y in the trails correlated very well with the measurement results. The model results indicate that HNO_3 is created within the trails already at short time intervals after the emission, which being a relatively stable trace gas should remain as the signature of the aircraft emissions. In addition to this, at least for the period under investigation (up to one hour after emission of the exhaust gases), under the conditions of high solar irradiation the influence of the trails on the oxidation capacity of the atmosphere is not significant. (orig.)SIGLEAvailable from TIB Hannover: RR 1618(38) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman