Concentration of trace gases in the lower troposphere,simultaneously recorded at neighboring mountain stations Part II: Ozone

Summary Long-term ozone recordings at different altitude levels, conducted in remote areas, can make a valuable contribution to an understanding of the background level of ozone, its periodical variations and possible long-term trends.The measuring stations (three high mountain stations between 740 and nearly 3000 m a.s.l. with small horizontal distance) are described together with recording and calibration procedures. Information is provided on the time history of all recordings since 1978, considering not only the annual means but also the monthly and 10-day means as a function of height. An analysis is presented of the annual variations which differ considerably in the respective height levels and—in three-dimensional diagrams—the correlation between daily and annual variation is shown as a function of height. Then follows a careful parameterization: analysis of the frequency distribution of the ozone concentration, correlation with relative humidity, relative sunshine duration, and temperature. It can be seen that the correlations are very different and partly inverse, depending on the altitude level.Many ozone profiles obtained between valley level and nearly 3000 m a.s.l. (cable car O₃ radiosonde) give a picture of the typical ozone profile for different meteorological situations and for the case of stratospheric intrusions of ozone into the troposphere. The stratospheric contribution of ozone to the tropospheric ozone budget is discussed.Since obviously a very high photochemical production rate can be established for ozone in the lowest layer above ground (correlation of O₃ with the daily variation of the sunshine duration) it was examined if this O₃ variation might be caused only by horizontal transport of ozone from remote areas with high anthropogenic activity by the daily quasiperiodical currents near the ground. But this is not the case.The correlation between ozone concentration, other trace gases such as nitrogen-oxygen compounds and hydrocarbons is shown.With 29 Figures