Author(s)

Stefan Bronnimann, Urs Neu and Heinz Wanner

Abstract

Correlations between Total Ozone and Near-Surface Ozone at Mountain Sites in Switzerland in Late Winter Guest contribution Stefan Bronnimann, Urs Neu and Heinz Wanner Institute of Geography, University of Bern, Hallerstr. 12, CH-3012 Bern, Switzerland Introduction The impact of changing UV radiation on tropospheric chemistry has become an important issue in environmental research in recent years. Theoretical considerations suggest that with increased UV radiation ozone photolysis and thus the formation of OH radicals is enhanced. This leads to an increase or decrease of near-surface ozone formation, depending on the NOx concentrations. Different model calculations (Liu and Trainer, 1988; Kriiger et #/., 1997) agree that an increase is expected for a polluted and a decrease for a clean atmosphere. Liu and Trainer (1988) calculated a threshold of 0.17 ppb NO% at 40° N in summer. Bronnimann and Neu (19

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