Articles | Volume 9, issue 3
Research article
14 Mar 2016
Research article |  | 14 Mar 2016

Long-term validation of ESA operational retrieval (version 6.0) of MIPAS Envisat vertical profiles of methane, nitrous oxide, CFC11, and CFC12 using balloon-borne observations and trajectory matching

Andreas Engel, Harald Bönisch, Tim Schwarzenberger, Hans-Peter Haase, Katja Grunow, Jana Abalichin, and Stephan Sala

Abstract. MIPAS-Envisat is a satellite-borne sensor which measured vertical profiles of a wide range of trace gases from 2002 to 2012 using IR emission spectroscopy. We present geophysical validation of the MIPAS-Envisat operational retrieval (version 6.0) of N2O, CH4, CFC-12, and CFC-11 by the European Space Agency (ESA). 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 in 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. The more recent low spectroscopic resolution data above 20 km altitude show agreement with the combined uncertainties, while there is a tendency of the earlier high spectral resolution data set to underestimate these species above 25 km. The earlier high spectral resolution data show a significant overestimation of the mixing ratios for N2O, CH4, and CFC-12 below 20 km. These differences need to be considered when using these data. The CFC-11 results from the operation retrieval version 6.0 cannot be recommended for scientific studies due to a systematic overestimation of the CFC-11 mixing ratios at all altitudes.

Short summary
We present a validation of MIPAS-ENVISAT vertical profiles (ESA operational retrieval version 6.0) of N2O, CH4, CFC-12, and CFC-11. The geophysical validation is performed using data from a balloon-borne cryogenic whole air sampler and trajectory matching. We show that the validation results are different for the period prior to 2005 compared to the post 2005 period. N2O, CH4, and CFC-12 show partly good agreement while CFC-11 data from this retrieval cannot be used for scientific studies.