In the ultraviolet and visible of the solar spectrum nadir measurements of space borne spectrometers like GOME and SCIAMACHY are sensitive to the state of polarization of the observed light. The correction for this polarization sensitivity is based on broadband polarization measurements (PMDs). However, due to atmospheric absorption and inelastic Raman scattering the state of polarization is varying rapidly with wavelength, which causes a insufficient polarization correction and severely limits the accuracy of atmospheric parameters retrieved from polarization corrected measurements. In this presentation we demonstrate that this problems due to the instrument polarization sensitivity can be solved in a natural way by the use of polarization modeling. For the forward of a retrieval algorithm we propose the combination of a vector radiative transfer model to simulate the transport of radiation in the probed atmosphere including inelastic Raman scattering in first order and a straight forward simulation of the instrument sensitivity by use of the Mueller matrix approach.