Calibration of aperture synthesis radiometers: the MIRAS/SMOS case

Tutorial de 4 hores impartit al International Geoscience and Remote Sensing Symposium. IGARSS 2012. Munich. GermanySMOS is the acronym for the Soil Moisture and Ocean Salinity mission by the European Space Agency (ESA). Its single payload, the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), was launched in November 2009. After a six months Commissioning Phase SMOS entered in operational mode in May 2010. Since then SMOS has been delivering a large amount of data to successfully produce the first relevant scientific results. MIRAS requires a complex multi-step calibration procedure that was successfully tested both during pre-flight ground tests and Commissioning Phase activities. Additionally, an assessment of SMOS system performance in terms of short and long term stability, radiometric sensitivity and radiometric accuracy was also produced. In this context, this tutorial is devoted to provide an overview of MIRAS calibration scheme by focusing on the rationale behind it. The course will be illustrated with relevant calibration and system performance plots from SMOS ground, commissioning and operational phase tests. 1.-Basic calibration concepts in aperture synthesis radiometry 2.-SMOS calibration rationale 2.1.- Error model and error budget 3.- SMOS calibration modes classification 3.1 Internal, external and ground calibration 4.- SMOS Calibration performance 4.1 Residual calibration errors 4.2 Calibration periodicity 5.- Brightness temperature retrievals 5.1.- ThePeer Reviewe