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UP: Fachverband Umweltphysik

UP 10: Poster: Umweltphysik

UP 10.5: Poster

Thursday, March 5, 2009, 17:48–19:00, VMP 9 Poster

Satellite validation of column-averaged methane on global scale: Harmonized data from 13 FTIR ground stations versus last generation ENVISAT/SCIAMACHY retrievals — R. Sussmann, •F. Forster, T. Borsdorff, and FTIR validation team — Research Center Karlsruhe, IMK-IFU, Garmisch-P.

Global measurements of column-averaged methane have recently shown a step forward in data quality via year 2003 and 2004 retrievals from two different processors (Frankenberg et al., 2008; Buchwitz et al., 2008). Accuracy and precision have approached the order of 1 %, and can be considered for inverse modelling of sources and sinks. This means that quality requirements for ground-based validation data have become higher. In order to guarantee a consistency of <1 % we performed a harmonization effort for 13 globally distributed mid-infrared FTIR stations. Station-to-station biases are eliminated by using identical micro-windows, spectroscopic line lists, retrieval parameters, sources of ancillary data like pressure-temperature profiles, and water vapor data for deriving dry air columns. Furthermore, a geophysically consistent set of prior information for the retrievals at all stations was established. Our study utilizes the validation strategy developed during the first validation of ENVISAT/SCIAMACHY column-averaged methane by FTIR (Sussmann et al., 2005). The outcome of the new study is the accurate determination of the satellite-ground station biases as a function of latitude on global scale, as well as an assessment of the ability of ENVISAT/SCIAMACHY to measure true day-to-day variability.