Surface ozone observations at Mt. Cimone Observatory (Italy)

摘要

Troposphere ozone concentration has been monitored since March 1991 at the Mt. Cimone Observatory (44$DGR@12' N, 10$DGR@42' E, 2165 m asl), a mountain site far from sources of anthropogenic pollution. The yearly trends of surface ozone concentration clearly evince a variation marked by peaks in spring and summer. That no ozone diurnal variations are usually found in late autumn, winter and early spring means that Mt. Cimone can be considered a baseline station over this period. In the warmer months, the daily ozone variation is affected by local mixing with the upwelling of ozone-poor low tropospheric air over the mid-daytime hours. Screening out the latter values, as well as those induced by horizontal transport phenomena from the pollutant-rich Po valley lowlands, yields free tropospheric ozone concentrations.