The Microwave Limb Sounder (MLS) instrument on NASA's Aura spacecraft observes ozone in Earth's stratosphere. In mid-March 2011 MLS measured very low ozone amounts (purple and grey colors over the north polar region) at an altitude of approximately 12 miles (20 kilometers). Large amounts of chlorine monoxide -- the primary agent of chemical ozone destruction in the cold polar lower stratosphere -- were observed for the same day and same altitude (dark blue colors). The white line marks the area within which the chemical ozone destruction took place.
On July 15, 2004, NASA's Aura spacecraft launched from California's Vandenberg Air Force Base on a mission to study Earth's ozone layer, air quality and climate. Aura's data are helping scientists address global climate change issues such as global warming; the global transport, distribution and chemistry of polluted air; and ozone depletion in the stratosphere, the layer of Earth's atmosphere that extends from roughly 15 to 50 kilometers (10 to 30 miles) in altitude.
Aura is the third and final major Earth Observing System satellite. Aura carries four instruments: the Ozone Monitoring Instrument, built by the Netherlands and Finland in collaboration with NASA; the High Resolution Dynamics Limb Sounder, built by the United Kingdom and the United States; and the Microwave Limb Sounder and Tropospheric Emission Spectrometer, both built by JPL. Aura is managed by NASA's Goddard Space Flight Center, Greenbelt, Md.
The Microwave Limb Sounder is a second-generation instrument that is helping scientists improve our understanding of ozone in Earth's stratosphere, especially how it is depleted by processes of chlorine chemistry. The instrument measures naturally occurring microwave thermal emission from the edge of Earth's atmosphere to remotely sense vertical profiles of atmospheric gases, temperature, pressure and cloud ice.