Analysis of Uncertainties in using TCCON for GOSAT and SCIAMACHY Validation
Deutscher, Nicholas1; Notholt, Justus1; Sherlock, Vanessa2; Griffith, David3; Velazco, Voltaire3; Wunch, Debra4; Wennberg, Paul4; Toon, Geoffrey5; Mikaloff Fletcher, Sara2; Buschmann, Matthias1
1University of Bremen, GERMANY; 2National Institute of Water and Atmospheric Research, NEW ZEALAND; 3University of Wollongong, AUSTRALIA; 4California Institute of Technology, UNITED STATES; 5Jet Propulsion Laboratory, UNITED STATES

The Total Carbon Column Observing Network is an expanding network currently consisting of approximately 17 sites globally, making measurements of the vertically-integrated atmospheric burden of greenhouse gases CO2, CH4 and others. Due to the high-precision and accuracy of TCCON measurements, to date TCCON has been used as the primary validation tool for satellite measurements of CO2 and CH4 from GOSAT and SCIAMACHY. As the precision and accuracy of satellite CO2 and CH4 retrievals improves, any, particularly systematic, uncertainties in the TCCON data become relatively more important. In this paper we investigate the impact of known error sources in the TCCON data, including residual airmass-dependent biases, laser-sampling errors and the effect of instrument alignment. In addition, we use modeling tools to investigate the validity of bias-corrections based on the assumption that no large gradients exist in the southern hemisphere extra-tropics.