Analysis of averaged broadband residuals between MIPAS-Envisat spectra and line-by-line calculations

MIPAS-Envisat spectra are compared to broadband spectra calculated with the KOPRA radiative transfer algorithm, using atmospheric temperature and trace gas concentrations which have been derived from small spectral ranges, so called microwindows, of the MIPAS-Envisat spectra. The objective is to detect instrumental problems and inconsistencies in the retrievals as well as in the spectroscopic dataset. The HITRAN 2008 spectroscopic database is used for all calculations. In this paper, we discuss residuals between modelled and measured broadband spectra which are caused by inconsistencies in the HITRAN O 3 and HNO 3 datasets. We conclude that the intensity of the 16O 16O 18O Q-branch around 1090.3cm -1 is too low. HNO 3 spectroscopy has turned out to be largely improved in the HITRAN 2008 version. However, even these spectroscopic data still produce spectral radiances too low at 885.45 and 886.15cm -1. Generally the calculated spectral radiance in the ν 5/2ν 9 region is slightly too low. © 2012 Elsevier Ltd.