Modell-Studien zur Chemie der arktischen Stratosphäre : simulierte Ozonverlustraten im Vergleich zu Ergebnissen der Matchanalysen

• Main Author: Becker, G.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Forschungszentrum, Zentralbibliothek 1999
• Subjects: Arktis*
• Online Access: https://juser.fz-juelich.de/record/39973; https://juser.fz-juelich.de/search?p=id:%22PreJuSER-39973%22

The aim of this thesis was a quantitative test of the current understanding of the stratospheric ozone chemistry in the Arctic winter. For that purpose box model studies corresponding to the Match analyses of the winters 1991/92 and 1994/95 were carried out. The Match technique allows the determination of the chemically induced ozone loss from a statistical analysis of pairs of ozonesonde measurements that took place at different times and locations of a calculated air mass trajectory. Under twilight conditions, as they are typical for the polar winter, the ozone loss rate strongly varies with the solar zenith angle. Thus it was necessary to simulate the ozone loss along each of the Match trajectories to obtain results quantitatively comparable to the Match analyses. In order to obtain initial values for these model runs the seasonal development of the relevant trace gas mixing ratios was simulated using idealized trajectories. It could be shown that the model significantly underestimates the early winter ozone loss. The Match dataset of the winter 1991/92 allows a time dependent comparison of the ozone loss rates only on the 475 K potential temperature level (~ 19 km). From mid February on the ozone loss rates are well reproduced by the model. But during the period of maximum ozone loss rates, from mid January to mid February, the modeled values are considerably lower than the Match results. Extensive sensitivity studies show that this discrepancy can not be explained by uncertainties of model parameters. For the winter 199'1/95, the height dependence of the ozone loss rates could also be examined. The ozone loss rates simulated for early winter 1994/95 agree well with the Match results for potential temperatures below 475 K. But for potential temperatures above 475 K the model underestimates the ozone loss rates by up to a factor of two. In the winter 1994/95 significant ozone loss occurred not only in early winter but also during a cold period in Marcil. Therefore the ozone loss accumulated over the winter ...