Human activities are changing the Earth and its atmosphere. Long-term records show a rise in the global average temperature over the past few decades. Other observations reveal changes in the composition of the Earth’s atmosphere such as thinning of the stratospheric ozone layer and increases in the concentration of greenhouse gases. Scientists do not fully understand how these changes will affect climate. Therefore, highly accurate, long-term measurements are essential for gaining a better understanding of the processes that control climate change.

Artist rendering of the Russian Meteor 3M spacecraft with the SAGE III instrument onboard.

The Stratopsheric Aerosol and Gas Experiment (SAGE III) is a fourth-generation satellite instrument designed to observe the long-term health of the upper atmosphere. Managed by NASA Langley Research Center, SAGE III is part of NASA’s Earth Science Enterprise program of climate research. It launched aboard a Russian Meteor 3M spacecraft in December 2001 for a three year mission, a collaboration between NASA and the Russian Aviation and Space Agency (RASA). It extends a long-term working relationship between the United States and Russia to understand Earth’s environment.

The goal of SAGE III is to measure high-resolution vertical profiles of key components of the upper atmosphere—the most important being ozone, aerosols, (suspended particles) and water vapor. These measurements will enhance our understanding of climate and how human activities influence it. This information will enable national and international leaders to make informed policy decisions on climate change.

next: Aerosols and volcanic eruptions

by Julia Cole
March 5, 2002

SAGE III
Introduction
Aerosols and volcanic eruptions
Ozone in the upper atmosphere
Water vapor observations
Making measurements at the edge of the Earth