OVERVIEW

Since the 1950's, it has become increasingly clear that human activities are modifying the composition of the atmosphere on a global scale. As the result of industrialization, the concentration of carbon dioxide has increased by about 20% during this period. (reference: Carbon Dioxide Information Analysis Center)

More recently, the stratospheric concentrations of chemically-active gases containing chlorine, bromine, and fluorine have dramatically increased (reference: World Climate Research Program).

These trends have created issues of global interest including global warming and declining levels of ozone (both globally and in the ozone "hole" in the Antarctic), which is needed to shield the Earth from harmful ultra-violet radiation.

It has become increasingly clear, however, that these processes do not occur independently of one another and can only be understood in the context of a global system. Accurate and precise measurements are needed to unravel complex and interactive relationships between chemical, radiative, and dynamical processes in the atmosphere, ocean, and on land.

NASA's Earth Observing System (EOS) consists of a series of spaceborne instruments to monitor crucial components of the Earth system, an advanced data handling system, and teams of scientists who will evaluate on-going climate change and predict future changes.

Ultimately, EOS will produce scientifically sound recommendations for environmental policy to national and international bodies to mitigate or prepare for these changes.

SAGE III's role in the EOS program is to provide global, long-term measurements of key components of the Earth's atmosphere. The most important of these are the vertical distribution of aerosols and ozone from the upper troposphere through the stratosphere.

In addition, SAGE III also provides unique measurements of temperature in the stratosphere and mesosphere and profiles of trace gases such as water vapor and nitrogen dioxide that play significant roles in atmospheric radiative and chemical processes.

The SAGE III Science Team functions in a dual role where they ensure the data quality and interpret the SAGE III data in the broader context of global change.

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