SIDE BY SIDE MEASUREMENTS OF GREENHOUSE GASES BY GROUND-BASED FOURIER TRANSFORM INFRARED (FTIR) SPECTROMETRY

Atmospheric inversion studies of greenhouse gases currently rely on a combination of in situ measurements. In-situ measurements are highly precise but also have their limitations. The spatial coverege is limited and the vertical transport is not well known. These two factors limit the confidence in source-sink estimates derived from the corresponding models. Satellite observations can cover the whole globe, and their analysis does not depend on the vertical transport. They need to be validated by ground-based observations, measuring the same quantity, the total column. The ground-based solar absorption FTIR-spectrometry has been found suitable for this purpose. However, all ground-based instruments involved in a validation need to be absolutely comparable. The Institute of Environmental Physics (IUP) in Bremen, Germany performs intensive side-by-side measurements. In the framework of two EU-projects GEOMON and IMECC two fully automated FTIR-systems were built at the Institute and were successfully installed in Bialystok (Poland) and Orleans (France). Preliminary results of these comparability studies and first measurements of the sites will be presented.