^b Shiomi, K., S. Kawakami, T. Kina, Y. Mitomi, M. Yoshida, N. Sekio, F. Kataoka, and R. Higuchi, 2007, Calibration of the GOSAT sensors, in Sensors, Systems, and Next-Generation Satellites XI, Proceedings of SPIE, 6744, 67440G; Akihiko Kuze, Japan Aerospace Exploration Agency, Personal communication, 2009; Hamazaki, T., Y. Kaneko, A. Kuze, and H. Suto, 2007, Greenhouse gases observation from space with TANSO-FTS on GOSAT, in Fourier Transform Spectroscopy/Hyperspectral Imaging and Sounding of the Environment, Optical Society of America Technical Digest Series, paper FWB1.

^c <http://envisat.esa.int/instruments/sciamachy/>; Burrows, J.P., E. Hölzle, A.P.H. Goede, H. Visser, and W. Fricke, 1995, “SCIAMACHY—Scanning Imaging Absorption Spectrometer for Atmospheric Chartography, Acta Astronautica, 35, 445-451; Noël, S., H. Bovensmann, J.P. Burrows, J. Frerick, K.V. Chance, A.P.H. Goede, and C. Muller, 1998, The SCIAMACHY instrument on ENVISAT-1, in Sensors, Systems, and Next-Generation Satellites II, Proceedings of SPIE, 3498, 94-104; Buchwitz, M., R. de Beek, S. Noël, J.P. Burrows, H. Bovensmann, H. Bremer, P. Bergamaschi, S. Körner, and M. Heimann, 2005, Carbon monoxide, methane and carbon dioxide columns retrieved from SCIAMACHY by WFM-DOAS: Year 2003 initial data set, Atmospheric Chemistry and Physics, 5, 3313-3329.

^d Aumann, H.H., M.T. Chahine, C. Gautier, M.D. Goldberg, E. Kalnay, L.M. McMillin, H. Revercomb, P.W. Rosenkranz, W.L. Smith, D.H. Staelin, L.L. Strow, and J. Susskind, 2003, AIRS/AMSU/HSB on the Aqua Mission: Design, science objectives, data products, and processing systems, IEEE Transactions on Geoscience and Remote Sensing, 41, 253; Chahine, M.T., L. Chen, P. Dimotakis, X. Jiang, Q. Li, E.T. Olsen, T. Pagano, J. Randerson, and Y.L. Yung, 2008, Satellite remote sounding of mid-tropospheric CO₂, Geophysical Research Letters, 35, L17807, doi:10.1029/2008GL035022.

^e Phulpin, T., D. Blumstein, F. Prel, B. Tournier, P. Prunet, and P. Schlüssel, 2007, Applications of IASI on MetOp-A: First results and illustration of potential use for meteorology, climate monitoring, and atmospheric chemistry, in Atmospheric and Environmental Remote Sensing Data Processing and Utilization III: Readiness for GEOSS, Proceedings of SPIE, 6684, 66840F; Crevoisier, C., A. Chedin, H. Matsueda, T. Machida, R. Armante, and N.A. Scott, 2009, First year of upper tropospheric integrated content of CO₂ from IASI hyperspectral infrared observations, Discussion, Atmospheric Chemistry and Physics, 9, 8187-8222.

^f Instantaneous field-of-view/Swath.

^g The uncertainty represents the estimate of random errors (e.g., the effects of detector noise) and additional systematic errors (e.g., bias caused by cloud and aerosol effects) unaccounted for or otherwise eliminated from the total error. Bias is reduced by successful validation efforts.

The GOSAT uncertainty is dominated by the precision (random errors). For OCO, Crisp et al. (2004) and Miller et al. (2007) discuss the observational system simulation experiments, including modeling of the OCO instrument performance characteristics, that led to an instrument design that would meet a measurement requirement of 1 ppm. The as-built OCO instrument performance was verified during prelaunch tests, which included direct solar observations. The analysis of the latter gave the best confirmation that the as-built instrument performance exceeded its design requirements. See Crisp, D., R.M. Atlas, F.-M. Breon, L.R. Brown, J.P. Burrows, P. Ciais, B.J. Connor, S.C. Doney, I.Y. Fung, D.J. Jacob, C.E. Miller, D. O’Brien, S. Pawson, J.T. Randerson, P. Rayner, R.J. Salawitch, S.P. Sander, B. Sen, G.L. Stephens, P.P. Tans, G.C. Toon, P.O. Wennberg, S.C. Wofsy, Y.L. Yung, Z. Kuang , B. Chudasama, G. Sprague, B. Weiss, R. Pollock, D. Kenyon, and S. Schroll, 2004, The Orbiting Carbon Observatory (OCO) mission, Advances in Space Research, 34, 700-709; Miller, C.E., D. Crisp, P.L. DeCola, S.C. Olsen, J.T. Randerson, A.M. Michalak, A. Alkhaled, P. Rayner, D.J. Jacob, P. Suntharalingam, D.B.A. Jones, A.S. Denning, M.E. Nicholls, S.C. Doney, S. Pawson, H. Bösch, B.J. Connor, I.Y. Fung, D. O’Brien, R.J. Salawitch, S.P. Sander, B. Sen, P. Tans, G.C. Toon, P.O. Wennberg, S.C. Wofsy, Y.L. Yung, and R.M. Law, 2007, Precision requirements for space-based XCO2 data, Journal of Geophysical Research, 112, D10314, doi:10.1029/2006JD007659.

The methods for bias reduction and validation are the same for GOSAT and OCO. Washenfelder et al. (2006) demonstrated the OCO validation concept and the essential role of ground-based measurements for meeting those objectives. Bösch et al. (2006) used these ground-based measurements to validate SCIAMACHY CO₂. The GOSAT team also plans to use the same validation sites and instruments. OCO planned to include and use Aeronet measurements. The OCO validation plan purposely located ground-based validation measurements at ARM sites to capitalize on the wealth of ancillary atmospheric and surface measurements. See Bösch, H., G.C. Toon, B. Sen, R.A. Washenfelder, P.O. Wennberg, M. Buchwitz, R. deBeek, J.P. Burrows, D. Crisp, M. Christi, B.J. Connor, V. Natraj, and Y.L. Yung, 2006, Space-based near-infrared CO₂ measurements: Testing the OCO retrieval algorithm and validation concept using SCIAMACHY observations over Park Falls, Wisconsin, Journal of Geophysical Research, 111, D23302, doi:10.1029/2006JD007080;; Washenfelder, R.A., G.C. Toon, J.-F. Blavier, Z. Yang, N.T. Allen, P.O. Wennberg, S.A. Vay, D.M. Matross, and B.C. Daube, 2006, Carbon dioxide column abundances at the Wisconsin Tall Tower site, Journal of Geophysical Research, 111, D22305, doi:10.1029/2006JD007154.