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Gewählte Doctoral Thesis:

Michael Christian Fitzka (2014): CHARACTERISTICS OF SOLAR UV RADIATION AND STRATOSPHERIC OZONE IN AUSTRIA: CLIMATOLOGY, TRENDS AND VARIABILITY.
Doctoral Thesis - Institut für Meteorologie (BOKU-Met), BOKU-Universität für Bodenkultur, pp 72. UB BOKU obvsg

Abstract:

The concentration of stratospheric ozone, as well as the meteorological parameters cloud cover, surface albedo, and aerosols govern the intensity of UV radiation reaching the earth’s surface. These parameters are subject to changes in the past, the present and the future in the course of a changing global climate. The present work covers the characteristics of UV radiation and stratospheric ozone dependent on their governing factors in Austria. Special regard is given to the specific conditions at the Alpine meteorological observatory Hoher Sonnblick, i.e. complex topography, enhanced and quickly changing surface albedo, and cloud conditions. Continuous observations of spectral global UV irradiance and total ozone column have been performed on-site since late 1993 by the Institute of Meteorology of BOKU Wien, representing the main data basis for the present investigations. Trend analysis and estimation of long-term changes in time series of total and vertically resolved ozone reveals a significant increase in total ozone since 1994. A new selection method to determine thresholds for events with unusually high and low total ozone based on extreme value theory is proposed. The understanding of the long-term evolution of surface UV radiation plays a crucial role for assessing potential beneficial and harmful effects on the biosphere, with special regard to implications for human health. Positive trends in surface UV are attributed to changing cloud cover and decreasing aerosol optical depth. On a short time scale, the highest variability in surface UV levels is attributed to changes in total ozone, followed by clouds and albedo. Short-term variability at the shortest wavelengths due to ozone was found to be highest during late winter and early spring. During summer, the influence of ozone is surpassed by the impact of enhanced convective clouds during that time of year.

Betreuer: Kromp-Kolb Helga

1. Berater: Simic Stana

2. Berater: Weihs Philipp