Accuracy of profile retrievals from mm-wave spectra of ClO and N 2O

The retrieval accuracy of a Chahine-Twomey retrieval algorithm, acting on pressure-broadened mm-wave rotational spectra measured with ground-based equipment, is explored for two radically different profiles, the first representing a two-layered Antarctic ClO distribution having a maximum mixing ratio of ~1.5 ppbv and no tropospheric component, and the second representing a typical polar N ₂O profile, with a tropospheric mixing ratio of 300 ppbv dropping rapidly in the low to mid-stratosphere. The uncertainties or errors due to intrinsic retrieval limits, practical levels of random noise, uncertainties in input parameters (atmospheric temperature and pressure profiles, pressure broadening), and in calibration of instrument sensitivity are all explored, and an overall error budget established a function of altitude