retrieval and monitoring of atmospheric trace gas concentrations in nadir and limb geometry using the spaceborne sciamachy instrument the scanning imaging absorption spectrometer for atmospheric chartography sciamachy onboard the european envisat spacecraft performs continuous spectral observations of reflected scattered and transmitted sunlight in various observation geometries a unique feature of sciamachy is the capability of probing the atmosphere in three different observation geometriesthe nadir limb and occultation measurement modes in nadir mode column densities of trace gases are retrieved with a spatial resolution of typically 30 x 60 km using the differential optical absorption spectroscopy doas technique platt and perner 1983 alternating with the nadir measurement vertical profiles of absorber concentration in the stratosphere are derived in limb and occultation in this paper we present an overview over some applications of sciamachy data in spacebased monitoring of atmospheric pollution the doas algorithms for the retrieval of total column amounts from nadir spectra are briefly described and case studies of pollution events are presented we also illustrate the technique used to derive stratospheric concentration profiles from limb observations and show comparisons with other remote sensing systems special emphasis will be given to techniques which take advantage of sciamachys different viewing geometries in particular we will discuss the potential and limits of strategies to infer tropospheric abundances of o3 and no2