Total and tropospheric ozone changes: observations and numerical modelling

A survey has been made of total and tropospheric ozone dynamics in the cont ext of its impacts on climate, human health and ecosystems. Observation dat a on total ozone content (TOZ) in the atmosphere and relevant numerical mod elling results have been discussed as well as similar information for tropo spheric ozone, whose formation and changes are being determined by quite di fferent causes. A necessity has been emphasized to get more adequate global observational data on TOZ and tropospheric ozone (this is especially impor tant in the latter case, because information on tropospheric ozone is far f rom being complete). Unsolved problems relevant to both total and troposphe ric ozone have been briefly considered.