Articles | Volume 10, issue 6
Atmos. Meas. Tech., 10, 2209–2238, 2017
Atmos. Meas. Tech., 10, 2209–2238, 2017

Research article 13 Jun 2017

Research article | 13 Jun 2017

Comparisons of the Orbiting Carbon Observatory-2 (OCO-2) XCO2 measurements with TCCON

Debra Wunch1,12, Paul O. Wennberg1, Gregory Osterman2,1, Brendan Fisher2,1, Bret Naylor2,1, Coleen M. Roehl1, Christopher O'Dell3, Lukas Mandrake2,1, Camille Viatte1, Matthäus Kiel1,10, David W. T. Griffith4, Nicholas M. Deutscher4,5, Voltaire A. Velazco4, Justus Notholt5, Thorsten Warneke5, Christof Petri5, Martine De Maziere6, Mahesh K. Sha6, Ralf Sussmann7, Markus Rettinger7, David Pollard8, John Robinson8, Isamu Morino9, Osamu Uchino9, Frank Hase10, Thomas Blumenstock10, Dietrich G. Feist11, Sabrina G. Arnold11, Kimberly Strong12, Joseph Mendonca12, Rigel Kivi13, Pauli Heikkinen13, Laura Iraci14, James Podolske14, Patrick W. Hillyard14,19, Shuji Kawakami15, Manvendra K. Dubey16, Harrison A. Parker16, Eliezer Sepulveda17, Omaira E. García17, Yao Te18, Pascal Jeseck18, Michael R. Gunson2,1, David Crisp2,1, and Annmarie Eldering2,1 Debra Wunch et al.
  • 1California Institute of Technology, Pasadena, CA, USA
  • 2Jet Propulsion Laboratory, Pasadena, CA, USA
  • 3Colorado State University, Fort Collins, CO, USA
  • 4University of Wollongong, Wollongong, Australia
  • 5University of Bremen, Bremen, Germany
  • 6Royal Belgian Institute for Space Aeronomy, Brussels, Belgium
  • 7Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK-IFU), Garmisch-Partenkirchen, Germany
  • 8National Institute of Water and Atmospheric Research, Lauder, New Zealand
  • 9National Institute for Environmental Studies (NIES), Tsukuba, Japan
  • 10Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany
  • 11Max Planck Institute for Biogeochemistry, Jena, Germany
  • 12University of Toronto, Toronto, Canada
  • 13Finnish Meteorological Institute, Sodankylä, Finland
  • 14NASA Ames Research Center, Moffett Field, CA, USA
  • 15Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan
  • 16Los Alamos National Laboratory, Los Alamos, NM, USA
  • 17Izaña Atmospheric Research Center, Meteorological State Agency of Spain (AEMet), Tenerife, Spain
  • 18LERMA-IPSL, Sorbonne Universités, UPMC Univ Paris 06, CNRS, Observatoire de Paris, PSL Research University, 75005 Paris, France
  • 19Bay Area Environmental Research Institute, Petaluma, CA, USA

Abstract. NASA's Orbiting Carbon Observatory-2 (OCO-2) has been measuring carbon dioxide column-averaged dry-air mole fraction, XCO2, in the Earth's atmosphere for over 2 years. In this paper, we describe the comparisons between the first major release of the OCO-2 retrieval algorithm (B7r) and XCO2 from OCO-2's primary ground-based validation network: the Total Carbon Column Observing Network (TCCON). The OCO-2 XCO2 retrievals, after filtering and bias correction, agree well when aggregated around and coincident with TCCON data in nadir, glint, and target observation modes, with absolute median differences less than 0.4 ppm and RMS differences less than 1.5 ppm. After bias correction, residual biases remain. These biases appear to depend on latitude, surface properties, and scattering by aerosols. It is thus crucial to continue measurement comparisons with TCCON to monitor and evaluate the OCO-2 XCO2 data quality throughout its mission.

Short summary
This paper describes the comparisons between NASA's Orbiting Carbon Observatory (OCO-2) column-averaged dry-air mole fractions of CO2 with its primary ground-based validation network, the Total Carbon Column Observing Network (TCCON). The paper shows that while the standard bias correction reduces much of the spurious variability in the satellite measurements, residual biases remain.