Anatomy of the uncertainty of satellite vicarious calibration using radiosondes: concepts and preliminary results for microwave radiometric observations

• DOI: 10.1007/s42865-024-00073-y
• Publication Date: 2024-08-06T14:02:29Z
• Authors: Domenico Cimini; Vasileios Barlakas; Fabien Carminati; Francesco De Angelis; Francesco Di Paola; Alessandro Fassò; Donatello Gallucci; Sabrina Gentile; Tim Hewison; Salvatore Larosa; Fabio Madonna; Vinia Mattioli; Mario Montopoli; Filomena Romano; Marco Rosoldi; Mariassunta Viggiano; Axel Von Engeln; Elisabetta Riccia...
• Keywords: Satellite observations, microwave radiometry, vicarious calibration, radiosonde; 01 natural sciences; 0105 earth and related environmental sciences

Abstract Calibration of satellite observations is crucial for ensuring the quality of retrieved products essential for meteorological and climate applications. Calibration is obtained and monitored through a cascade of stages, including postlaunch vicarious calibration/validation activities through comparison with independent reference measurements. Here, the vicarious calibration method using radiative transfer simulations based on reference radiosondes is considered in the framework of the calibration/validation activities for the Microwave Imager (MWI) and the Ice Cloud Imager (ICI) to be launched with the Second Generation of the EUMETSAT Polar System. This paper presents an overview of the uncertainty characterizing the vicarious calibration of MWI and ICI using radiosondes as performed within the EUMETSAT-funded VICIRS study. The uncertainty characterization is pursued following a metrological approach, providing a preliminary estimation of all the identified sources. The same approach is used to develop a rigorous method for estimating the number of comparison pairs (i.e., observations vs. simulations) needed to reach a certain level of accuracy in bias determination.