Calibration of the Total Carbon Column Observing Network using aircraft profile data

The Total Carbon Column Observing Network (TCCON) produces precise measurements of the column average dry-air mole fractions of CO<sub>2</sub>, CO, CH<sub>4</sub>, N<sub>2</sub>O and H<sub>2</sub>O at a variety of sites worldwide. These observations rely on spectroscopic parameters that are not known with sufficient accuracy to compute total columns that can be used in combination with in situ measurements. The TCCON must therefore be calibrated to World Meteorological Organization (WMO) in situ trace gas measurement scales. We present a calibration of TCCON data using WMO-scale instrumentation aboard aircraft that measured profiles over four TCCON stations during 2008 and 2009. These calibrations are compared with similar observations made in 2004 and 2006. The results indicate that a single, global calibration factor for each gas accurately captures the TCCON total column data within error