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Vertical Ozone transports in the Alps II


VOTALP II is a follow-up project of VOTALP, already funded by the EC.It is the aim of VOTALP II to make best use of the insights gained so far, continuing the work on some topics, applying methods and models developed during VOTALP and investigating new important questions that arose from VOTALP.
In mountainous regions, the vertical exchange between the boundary layer and the free troposphere is significantly enhanced. This leads to a much stronger venting of pollutants into the free troposphere than above the lowlands, increasing tropospheric background concentrations of primary pollutants above Europe. As more ozone molecules per NOx molecule are formed under low-NOx conditions (in the free troposphere) than under high-NOx conditions (in the polluted boundary layer), the total ozone formation, averaged over both the boundary layer and the free troposphere, is enhanced. This motivates the fundamental question of VOTALP II:

What is the effect of the strong vertical exchange on the ozone concentrations in the Alps and in Europe as a whole?

This question shall be answered by case studies using Eulerian meteorological-photochemical model experiments with a flattened topography and long-term Lagrangian particle dispersion model runs with parameterized vertical exchange in the Alpine area. Several other topics that give the necessary background knowledge, but are also interesting for themselves, are investigated as well: the local ozone production in Alpine valleys and the effect of emission reductions, the ozone influx from the stratosphere, the effects of clouds on vertical exchange, the importance of vertical exchange in Alpine foothills, and the advection of urban plumes into the Alps.

Funding Scheme

CSC - Cost-sharing contracts


18,Turkenschanzstrasse 18
1180 Wien

Participants (1)

University of Ljubljana
1000 Ljubljana