Comparison of MIR and NIR xCO2 Retrievals for Validation of Greenhouse Gas Satellite Measurements
Buschmann, Matthias1; Deutscher, Nicholas1; Sherlock, Vanessa2; Dohe, Susanne3; Robinson, John2; Smale, Dan2; Schneider, Matthias3; Hase, Frank3; Jones, Nicholas4; Griffith, David4; Notholt, Justus1
1IUP Bremen, GERMANY; 2NIWA, NEW ZEALAND; 3KIT, GERMANY; 4University of Wollongong, AUSTRALIA
Monitoring networks like the NDACC (Network for the Detection of Atmospheric Composition Change) and TCCON (Total Carbon Column Observing Network) continuously monitor a variety of trace gases in the atmosphere by employing ground based Fourier Transform InfraRed (FTIR) spectroscopy on solar radiation. TCCON uses near infrared (NIR) spectral windows to retrieve total column CO2, which yield a high enough precision (<0.2%) to use as validation for satellite retrievals and model data. On the other hand, it has been considered difficult to obtain results with comparable precision from the middle infrared (MIR) from NDACC spectra. Most TCCON sites have been established relatively recently and cannot be used for longer term SCIAMACHY validation. It would therefore be useful to be able to use the longer time series of the NDACC stations and their more extensive geographic coverage to provide a time series for validating satellite retrievals dating back more than 20 years. Here we present an intercomparison study using different monitoring stations that routinely take both NIR and MIR spectra. This results in a validation scheme for a MIR time series based on the already well validated TCCON data.