This report describes the activity we have performed within phase I of the project EUM/CO/11/4600000996/PDW. This phase has been mostly dedicated to perform a review of state of art methodologies and tools concerning the exploitation of spatial and temporal variability to improve retrieval products from satellite observations of infrared radiances. The study is mostly aimed at defining a suitable retrieval methodology for the infrared channels of the Meteosat Second Generation (MSG) SEVIRI (Spinning Enhanced Visible and Infrared Imager) and in perspective for the METEOSAT Third Generation (MTG) Infrared Sounder.To date, the retrieval of geophysical parameters from satellite observations largely relies on a-priori information, which is derived from climatology and/or models for Numerical Weather Prediction. Thus, the retrieval problem can be efficiently analyzed within the broad context of data assimilation …