NASA Orbiting Carbon Observatory: measuring the column averaged carbon dioxide mole fraction from space

The NASA Orbiting Carbon Observatory (OCO) will make space-based measurements of atmospheric carbon dioxide (CO 2) with the precision, resolution, and coverage needed to characterize regional scale CO 2 sources and sinks and quantify their vari¬ability over the seasonal cycle. This mission will be launched in December 2008 and will fly in a 705 km altitude, 1:26 PM sun-synchronous orbit that provides complete coverage of the sunlit hemisphere with a 16-day ground track repeat cycle. OCO carries a single instrument designed to make co-boresighted spectroscopic measurements of reflected sunlight in near-infrared CO 2 and molecular oxygen (O 2) bands. These CO 2 and O 2 measurements will be combined to provide spatially resolved estimates of the column averaged CO 2 dry air mole fraction, X CO2. The instrument collects 12 to 24 X CO2 soundings/second over the sunlit portion of the orbit, yielding 200 to 400 soundings per degree of latitude, or 7 to 14 million soundings every 16 days. Existing studies indicate that at least 10% of these soundings will be sufficiently cloud free to yield X CO2 estimates with accuracies of ~0.3 to 0.5% (1 to 2 ppm) on regional scales every month.

[1]  Mark R. Schoeberl.  The afternoon constellation: a formation of Earth observing systems for the atmosphere and hydrosphere , 2002, IEEE International Geoscience and Remote Sensing Symposium.

[2]  Justus Notholt,et al.  Seasonal and latitudinal variations of column averaged volume‐mixing ratios of atmospheric CO2 , 2005 .

[3]  P ? ? ? ? ? ? ? % ? ? ? ? , 1991 .

[4]  G. Toon,et al.  Spaceborne measurements of atmospheric CO2 by high‐resolution NIR spectrometry of reflected sunlight: An introductory study , 2002 .

[5]  P. Rayner,et al.  The utility of remotely sensed CO2 concentration data in surface source inversions , 2001 .

[6]  V. Malathy Devi,et al.  Line strengths of 12C16O2: 4550–7000 cm−1 , 2006 .

[7]  Corinne Le Quéré,et al.  Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks , 2007, Proceedings of the National Academy of Sciences.

[8]  Hartmut Boesch,et al.  Evaluation of errors from neglecting polarization in the forward modeling of O2 A band measurements from space, with relevance to CO2 column retrieval from polarization-sensitive instruments , 2007 .

[9]  G. Toon,et al.  Carbon dioxide column abundances at the Wisconsin Tall Tower site , 2006 .

[10]  V. Malathy Devi,et al.  Self-broadened widths and shifts of 12C16O2: 4750–7000 cm−1 , 2006 .

[11]  Scott C. Doney,et al.  Variational data assimilation for atmospheric CO2 , 2006 .

[12]  David Crisp,et al.  The Orbiting Carbon Observatory instrument optical design , 2004, SPIE Optics + Photonics.

[13]  David Crisp,et al.  The Orbiting Carbon Observatory (OCO) mission , 2004 .

[14]  James T. Randerson,et al.  Differences between surface and column atmospheric CO2 and implications for carbon cycle research , 2004 .

[15]  Aaas News,et al.  Book Reviews , 1893, Buffalo Medical and Surgical Journal.

[16]  Peter J. Rayner,et al.  Global observations of the carbon budget, 2, CO2 column from differential absorption of reflected sunlight in the 1.61 μm band of CO2 , 2002 .

[17]  David Crisp,et al.  Precision requirements for space-based XCO2 data , 2007 .

[18]  James D. Spinhirne,et al.  Scattering layer statistics from space borne GLAS observations , 2005 .