06 Jun 2023
 | 06 Jun 2023
Status: a revised version of this preprint is currently under review for the journal ESSD.

CLAAS-3: the third edition of the CM SAF cloud data record based on SEVIRI observations

Nikos Benas, Irina Solodovnik, Martin Stengel, Imke Hüser, Karl-Göran Karlsson, Nina Håkansson, Erik Johansson, Salomon Eliasson, Marc Schröder, Rainer Hollmann, and Jan Fokke Meirink

Abstract. CLAAS-3, the third edition of the Cloud property dAtAset using SEVIRI, was released in December 2022. It is based on observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI), on board geostationary satellites Meteosat-8, 9, 10 and 11, which are operated by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). CLAAS-3 was produced and released by the EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF), which aims to provide high quality satellite-based data records suitable for climate monitoring applications. Compared to previous CLAAS releases, CLAAS-3 is expanded in terms of both temporal extent and cloud properties included, and it is based on partly updated retrieval algorithms. The available data span the period from 2004 to present, covering Europe, Africa, the Atlantic Ocean and parts of South America, the Middle East and the Indian Ocean. They include cloud fractional coverage, cloud-top height, phase (liquid or ice) and optical and microphysical properties (water path, optical thickness, effective radius and droplet number concentration), from instantaneous data (every 15 minutes) to monthly averages. In this study we present an extensive evaluation of CLAAS-3 cloud properties, based on independent reference data sets. These include satellite-based retrievals from active and passive sensors, ground-based observations and in situ measurements from flight campaigns. Overall results show very good agreement, with small biases attributable to different sensor characteristics, retrieval/sampling approaches, and viewing/illumination conditions. These findings demonstrate the fitness of CLAAS-3 to support the intended applications, which include evaluation of climate models, cloud characterization and process studies focusing especially on the diurnal cycle, and cloud filtering for other applications. The CLAAS-3 data record is publicly available via the CM SAF website ( (Meirink et al., 2022).

Nikos Benas et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on essd-2023-79', Caroline Poulsen, 13 Jun 2023
  • RC2: 'Comment on essd-2023-79', Anonymous Referee #2, 26 Jul 2023
  • EC1: 'Comment on essd-2023-79', Tobias Gerken, 26 Jul 2023

Nikos Benas et al.

Data sets

CLAAS-3: CM SAF CLoud property dAtAset using SEVIRI - Edition 3 J. F. Meirink, K.-G. Karlsson, I. Solodovnik, I. Hüser, N. Benas, E. Johansson, N. Håkansson, M. Stengel, N. Selbach, M. Schröder, and R. Hollmann

Nikos Benas et al.


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Short summary
This manuscript describes CLAAS-3, the Cloud property dAtAset using SEVIRI, Edition 3, which was created based on observations from geostationary Meteosat satellites. CLAAS-3 cloud properties are evaluated using a variety of reference datasets, with very good overall results. The demonstrated quality of CLAAS-3 ensures its usefulness in a wide range of applications, including studies of local to continental scale cloud processes and evaluation of climate models, among others.