Long term validation of ESA operational retrieval (version 6.0) of MIPAS Envisat vertical profiles of methane, nitrous oxides, CFC-11 and CFC-12 using balloon borne observations and trajectory matching
Abstract. MIPAS-Envisat is a satellite-borne sensor which was measuring vertical profiles of a wide range of trace gases from 2002 to 2012 using IR emission spectroscopy. We present geophysical validation for the operational retrieval (version 6.0) of N2O, CH4, CFC-12 and CFC-11 by the European Space Agency (ESA) of MIPAS-Envisat. The geophysical validation data are derived from measurements of samples collected by a cryogenic whole air sampler flown to altitudes of up to 34 km by means of large scientific balloons. In order to increase the number of coincidences between the satellite and the balloon observations we applied a trajectory matching technique. The results are presented for different time periods due to a change in the spectroscopic resolution of MIPAS as of early 2005. Retrieval results for N2O, CH4 and CFC-12 show partly good agreement for some altitude regions, which differs for the periods with different spectroscopic resolution. However, significant differences to the balloon data are also observed for some altitude regions, which depend on species and spectroscopic resolution. These differences need to be considered when using these data. The CFC-11 results from the operation retrieval version 6 cannot be recommended for scientific studies due to a systematic overestimation of the CFC-11 mixing ratios.