Tropospheric ozone concentration at the tropopause. About 90% of total ozone in the atmosphere is in the stratosphere, and 10% is in the troposphere. Although tropospheric ozone is less concentrated than stratospheric ozone, it is of concern because of its health effects. Ozone in the troposphere is considered a greenhouse gas, and may contribute to global warming. Photo-chemical and chemical reactions involving ozone drive many of the chemical processes that occur in the troposphere by day and by night. At abnormally high concentrations (the largest source being emissions from combustion of fossil fuels), it is a pollutant, and a constituent of smog.
Global Ozone Monitoring by Occultation of Stars Global Ozone Monitoring by Occultation of Stars Global Ozone Monitoring by Occultation of Stars (GOMOS), is an instrument on board the European satellite Envisat launched 1 March 2002. It is the first space instrument dedicated to the study of the atmosphere of the Earth by the technique of stellar occultation. The spectrum of stars in the ultraviolet, visible and the near infrared parts of the electromagnetic spectrum is observed. It is aimed to use GOMOS to build a climatology of ozone and related species in the middle atmosphere (15 to 100 km). The 250-680 nm spectral domain is used for