Atmospheric Measurement Techniques Discussions www.atmos-meas-tech-discuss.net 1867-8610 2 4 2009 10.5194/amtd-2-1575-2009 http://www.atmos-meas-tech-discuss.net/2/1575/2009/ http://www.atmos-meas-tech-discuss.net/2/1575/2009/amtd-2-1575-2009.html http://www.atmos-meas-tech-discuss.net/2/1575/2009/amtd-2-1575-2009.pdf 1575 1624 2009-07-13 Non-Gaussian Bayesian retrieval of tropical upper tropospheric cloud ice and water vapour from Odin-SMR measurements B. Rydberg bengt.rydberg@chalmers.se P. Eriksson S. A. Buehler D. P. Murtagh Department of Radio and Space Science, Chalmers Univ. of Technology, Gothenburg, Sweden Department of Space Science, Luleå Univ. of Technology, Luleå, Sweden Improved Odin-SMR retrievals of upper tropospheric water are presented. The new retrieval algorithm retrieves humidity and cloud ice mass simultaneously and takes into account of cloud inhomogeneities. Both these aspects are introduced for microwave limb sounding inversions for the first time. A Bayesian methodology is applied allowing for a formally correct treatment of non-unique retrieval problems involving non-Gaussian statistics. Cloud structure information from CloudSat is incorporated into the retrieval algorithm. This removes a major limitation of earlier inversion methods where uniform cloud layers were assumed and caused a systematic retrieval error. The core part of the retrieval technique is the generation of a database that must closely represent real conditions. Good agreement with Odin-SMR observations indicates that this requirement is met. The retrieval precision is determined to be about 5–17% RHi and 65% for humidity and cloud ice mass, respectively. For both quantities, the vertical resolution is about 5 km and the best retrieval performance is found between 11 and 15 km. New data show a significantly improved agreement with CloudSat cloud ice mass retrievals, at the same time consistency with the Aura MLS humidity results is maintained. 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