| Authorship: Forster, F., Sussmann, R., Borsdorff, T., Rettinger, M., Blumenstock, T.,
Buchwitz, M., Burrows, J.P., Duchatelet, P., Frankenberg, C., Hannigan, J., Hase, F., Jones,
N., Klyft, J., Mahieu, E., De Mazière, M., Mellqvist, J., Notholt, J., Petersen, K., Schneising,
O., Strong, K., Taylor, J., Vigouroux, C.
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, namely
IMAP-DOAS ver. 49 and WFM-DOAS ver. 1.0 (Frankenberg et al., 2008; Schneising et al.,
2009). Accuracy and precision have approached the order of 1 %, and can be considered for
inverse modelling of sources and sinks. This means at the same time that the quality
requirements for ground-based validation data have become higher. In order to guarantee a
station-to-station consistency of |