Science Objectives: Ozone

Ozone research has remained at the forefront of atmospheric science for many years because stratospheric ozone shields the Earth's surface (and its inhabitants) from harmful ultraviolet radiation. Since recent declines in stratospheric ozone have been linked to human activity, accurate long-term measurements of ozone remain crucial. SAGE III ozone measurements will provide important contributions in the following areas:

• It is important to monitor ozone levels in the lower stratosphere and upper troposphere since observed trends are the largest and most poorly understood at those altitudes. SAGE III's high vertical resolution and long-term stability make it uniquely well suited to make these measurements.

• The relationship between aerosol, cloud, and chemical processes affecting ozone argue for simultaneous measurements of these atmospheric constituents (such as those made by SAGE III).

• Ozone is a strong greenhouse gas that modifies the macroscopic structure of the atmosphere. Changes in the amount of stratospheric ozone can lead to changes in sensible weather at the Earth's surface. Accurate simulations of climate change require accurate assessments of changes in ozone levels.

• Changing levels of ozone can also cause changes in other chemically and radiatively important gases including methane and the hydroxyl radical.

• Ozone can also be used as tracer of dynamic processes in the stratosphere which are difficult to directly observe. These include the transport of air from the tropics to mid-latitudes.