The spectrometer instrument SCIAMACHY is planned to be launched in 2001 to observe trace gas concentrations in the atmosphere. This instrument will alternately observe the same air mass in limb and nadir direction in the wavelength range of 240 to 2400 nm. The combination of these nadir and limb observations is likely to improve the ozone profile observations in the troposphere and stratosphere. In this sensitivity study the method of calculating the retrieval errors and covariances of the ozone profile values will be described, and the results will be presented for a few representative scenarios. It will be shown that the accuracy of ozone profile retrievals based on combined nadir/limb observations will no longer be limited by instrument noise. Therefore the accuracy of the retrieved ozone profiles in troposphere and stratosphere has the potential to be higher than of single-nadir observations from similar instruments. ¿ 2001 American Geophysical Union