[The two ozone problems: too much in the troposphere, too little in the stratosphere].

Trends analysis based on the long-term Swiss ozone measurements from Arosa and Payerne operationally performed by the Swiss Meteorological Institute are presented. These measurement include stratospheric ozone (approximately 90% of total ozone) and tropospheric ozone. The total ozone measurements from Arosa, the world longest series started at 1926, indicate, that total ozone has declined since about 1970 by approximately 5%. The ozone balloon soundings, operationally performed at Payerne since 1969 (2-3 ascents per week) show, that stratospheric ozone has decreased strongly in the last 20 years, whereas tropospheric ozone, remarkably has increased during this period. The relative change was strongest in the troposphere (more than 10% per decade, 3-4% increase per year during 1982-1988). However, on an absolute scale, changes in the stratosphere were strongest (relative decrease: 6 to 7% per decade at 20-22 km). The present scientific theories of the two ozone problems are reviewed: stratospheric ozone decrease was caused by the anthropogenic emissions of fluorochlorocarbons and other compounds mainly released from the earth surface. Tropospheric ozone has increased due to photochemical production of mainly anthropogenically emitted nitrogen oxides, volatile organic compounds and CO.