Understanding the chemistry of this planetary boundary layer is a key element to tropospheric science. Chemical reactions in the troposphere that lead to the conversion, redistribution, and removal of atmospheric chemicals are being studied through use of extensive airborne missions. The Global Tropospheric Experiment is one of NASA's major airborne mission based experiments to study the troposphere. Langley's participation in global tropospheric experiment missions have probed atmospheric chemical change over the Atlantic Ocean, tropical rainforest and Arctic tundra, returning dramatic new evidence of the importance of these ecosystems to the Earth's climate. Langley's MAPs instrument which flies on the space shuttle monitors carbon monoxide in the troposphere and has shown the importance of biomass burning as a significant source of carbon monoxide.
Biomass burning is an example of a critical human initiated activity affecting the troposphere.
From a global perspective, Langley is gaining knowledge of the distribution and abundance of tropospheric chemicals and the role they play in the chemical changes of the atmosphere. A new era in remote sensing has begun with operations involving lasers. Lasers provide small area coverage, high vertical resolution and sensitivity to atmospheric particles. It provided global measurements of multiple layer clouds and aerosols. ASD has observed continental haze, Saharan dust, Hurricane Melissa and aerosols produced during biomass burning.