AOSC Departmental Seminar
February 25, 2016

Watching the Earth Breathe - Measuring Atmospheric Carbon Dioxide with NASA’s Orbiting Carbon Observatory-2 (OCO-2)

David Crisp
Jet Propulsion Laboratory, California Institute of Technology

The Orbiting Carbon Observatory-2 (OCO-2) is the first NASA Earth Science mission designed to measure atmospheric carbon dioxide (CO2) with the precision, accuracy, resolution, and coverage required to quantify CO2 emission sources and natural sinks on regional scales over the globe. OCO-2 was successfully launched from Vandenberg Air Force Base in July of 2014. For just over a year, its 3-channel, imaging grating spectrometer has been routinely returning around one million observations of the column-averaged CO2 dry air mole fraction (XCO2) over the sunlit hemisphere each day. Global maps XCO2 compiled from these measurements clearly reveal some of the most robust features of the atmospheric carbon cycle. XCO2 enhancements co-located with intense fossil fuel emissions in eastern U.S. and eastern China are most obvious between October and December, when the north-south XCO2 gradient is small. Enhanced XCO2 coincident with biomass burning in the Amazon, central Africa, and Indonesian is also obvious in this season. In the late spring and early summer, when the north-south XCO2 gradient was largest, these sources were less apparent in global maps. From late May to mid-July, OCO-2 maps show a 2-3% reduction in XCO2 across the northern hemisphere, as photosynthesis by the land biosphere rapidly absorbs CO2. As noted above, these are some of the best known features of the global carbon cycle, but they have never before been observed at this resolution. As the carbon cycle community continues to analyze these OCO-2 data, quantitative estimates of regional-scale emission sources and natural sinks are expected to emerge.