Validation of Column-Averaged Dry-Air Mole Fraction of CO2 Retrieved from OCO-2 Using Ground-Based FTS Measurements

In order to correctly use the column-averaged atmospheric CO2 dry-air mole fraction (XCO2) data in the CO2 flux studies, XCO2 measurements retrieved from the Orbiting Carbon Observatory-2 (OCO-2) in 2015 were compared with those obtained from the global ground-based high-resolution Fourier Transform Spectrometer (FTS) participating in the Total Carbon Column Observing Network (TCCON). The XCO2 retrieved from three observing modes adopted by OCO-2, i.e., nadir, target, and glint, were separately validated by the FTS measurements at up to eight TCCON stations located in different areas. These comparisons show that OCO-2 glint mode yields the best qualitative estimations of CO2 concentration among the three operational approaches. The overall results regarding the glint mode show no obvious systematic biases. These facts may indicate that the glint concept is appropriate for not only oceans but also land regions. Negative systematic biases in nadir and target modes have been found at most TCCON sites. The standard deviations of XCO2 retrieved from target and nadir modes within the observation period are similar, and larger than those from glint mode. We also used the FTS site in Beijing, China, to assess the OCO-2 XCO2 in 2016. This site is located in a typical urban area, which has been absent in previous studies. Overall, OCO-2 XCO2 agrees well with that from FTS at this site. Such a study will benefit the validation of the newly launched TanSat products in China.

[1]  Jie Chen,et al.  Impacts of aerosol and albedo on TanSat CO2 retrieval using the near infrared CO2 bands , 2014, Asia-Pacific Environmental Remote Sensing.

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

[3]  M. Buchwitz,et al.  Space‐based near‐infrared CO2 measurements: Testing the Orbiting Carbon Observatory retrieval algorithm and validation concept using SCIAMACHY observations over Park Falls, Wisconsin , 2006 .

[4]  Dorit Hammerling,et al.  Global CO2 distributions over land from the Greenhouse Gases Observing Satellite (GOSAT) , 2012 .

[5]  Hartmut Boesch,et al.  Retrieval of from simulated Orbiting Carbon Observatory measurements using the fast linearized R-2OS radiative transfer model , 2008 .

[6]  Krzysztof Wargan,et al.  Strengthening of the Tropopause Inversion Layer during the 2009 Sudden Stratospheric Warming: A MERRA-2 Study , 2016 .

[7]  Scot M. Miller,et al.  Spatio-temporal approach to moving window block kriging of satellite data v 1 . 0 , 2016 .

[8]  David Crisp,et al.  Comparisons of the Orbiting Carbon Observatory-2 (OCO-2) X CO 2 measurements with TCCON , 2016 .

[9]  Jovan M. Tadić,et al.  Spatio-temporal approach to moving window block kriging of satellite data v1.0 , 2016 .

[10]  R. Bennartz,et al.  Estimating bias in the OCO-2 retrieval algorithm caused by 3-D radiation scattering from unresolved boundary layer clouds , 2014 .

[11]  John Robinson,et al.  Retrieval of atmospheric CO2 with enhanced accuracy and precision from SCIAMACHY: validation with FTS measurements and comparison with model results , 2011 .

[12]  R. Spurr,et al.  Retrieval of X CO 2 from simulated Orbiting Carbon Observatory measurements using the fast linearized R-2 OS radiative transfer model , 2008 .

[13]  C. Rinsland,et al.  Intercomparison of retrieval codes used for the analysis of high-resolution, ground-based FTIR measurements , 2004 .

[14]  Tatsuya Yokota,et al.  Global Concentrations of CO2 and CH4 Retrieved from GOSAT: First Preliminary Results , 2009 .

[15]  Vineet Yadav,et al.  Mapping of satellite Earth observations using moving window block kriging , 2014 .

[16]  C. Frankenberg,et al.  Evaluation and attribution of OCO-2 XCO 2 uncertainties , 2016 .

[17]  Rebecca Castano,et al.  The ACOS CO 2 retrieval algorithm – Part 1: Description and validation against synthetic observations , 2011 .

[18]  Liping Lei,et al.  Spatiotemporal correlation analysis of satellite-observed CO2: Case studies in China and USA , 2013, 2013 IEEE International Geoscience and Remote Sensing Symposium - IGARSS.

[19]  Justus Notholt,et al.  The Total Carbon Column Observing Network , 2011, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

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

[21]  James B. Abshire,et al.  Calibration of the Total Carbon Column Observing Network using aircraft profile data , 2010 .

[22]  David Crisp,et al.  Measuring atmospheric carbon dioxide from space with the Orbiting Carbon Observatory-2 (OCO-2) , 2015, SPIE Optical Engineering + Applications.

[23]  Tatsuya Yokota,et al.  Preliminary validation of column-averaged volume mixing ratios of carbon dioxide and methane retrieved from GOSAT short-wavelength infrared spectra , 2010 .

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