Retrieval of nitric oxide in the mesosphere and lower thermosphere from SCIAMACHY limb spectra

We use the ultra-violet (UV) spectra in the range 230-300 nm from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) to retrieve the nitric oxide (NO) number densities from atmospheric emissions in the gamma-bands in the mesosphere and lower thermosphere. Using 3-D ray tracing, a 2-D retrieval grid, and regularisation with respect to altitude and latitude, we retrieve a whole semi-orbit simultaneously for the altitude range from 60 to 160 km. We present details of the retrieval algorithm, first results, and initial comparisons to data from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Our results agree on average well with MIPAS data and are in line with previously published measurements from other instruments. For the time of available measurements in 2008-2011, we achieve a vertical resolution of 5-10 km in the altitude range 70-140 km and a horizontal resolution of about 9 from 60 S-60 N. With this we have independent measurements of the NO densities in the mesosphere and lower thermosphere with approximately global coverage. This data can be further used to validate climate models or as input for them. © 2013 Author(s).S. Bender and M. Sinnhuber thank the Helmholtz-society for funding this project under the grant number VH-NG-624. The IAA team (M. Lopez-Puertas and B. Funke) was supported by the Spanish MINECO under grant AYA2011-23552 and EC FEDER funds. The SCIAMACHY project was funded by German Aerospace (DLR), the Dutch Space Agency, SNO, and the Belgium ministry. ESA funded the Envisat project. The University of Bremen as Principal Investigator has led the scientific support and development of SCIAMACHY and the scientific exploitation of its data products. We acknowledge support by Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of Karlsruhe Institute of Technology.Peer Reviewe