{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,23]],"date-time":"2026-04-23T00:47:54Z","timestamp":1776905274797,"version":"3.51.2"},"reference-count":45,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2022,11,3]],"date-time":"2022-11-03T00:00:00Z","timestamp":1667433600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100015235","name":"Leibniz Institute for Tropospheric Research","doi-asserted-by":"publisher","award":["4-7323\/29\/5-2021\/2017"],"award-info":[{"award-number":["4-7323\/29\/5-2021\/2017"]}],"id":[{"id":"10.13039\/501100015235","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Given the important role of clouds in our planet\u2019s climate system, it is crucial to further improve our understanding of their governing processes as well as the resulting spatio-temporal variability of their properties. This co-variability of different cloud optical properties is adequately represented through the well-established concept of cloud regimes. The focus of the present study lies on the creation of a cloud regime dataset over Europe, named \u201cCloud Regime dAtAset based on the CLAAS-2.1 climate data record\u201d (CRAAS), in order to analyze their variability and their changes at different spatio-temporal scales. In addition, co-occurrences between the cloud regimes and large-scale weather patterns are investigated. The CLoud property dAtAset using Spinning Enhanced Visible and Infrared (SEVIRI) edition 2.1 (CLAAS-2.1) data record, which is produced by the Satellite Application Facility on Climate Monitoring (CM SAF), was used as the basis for the derivation of the cloud regimes over Europe for a 14-year period (2004\u20132017). In particular, the cloud optical thickness (COT) and cloud top pressure (CTP) products of CLAAS-2.1 were used in order to compute 2D histograms. Then, the k-means clustering algorithm was applied to the generated 2D histograms in order to derive the cloud regimes. Eight cloud regimes were identified, which, along with the geographical distribution of their frequency of occurrence, assisted in providing a detailed description of the climate of the cloud properties over Europe. The annual and diurnal variabilities of the eight cloud regimes were studied, and trends in their frequency of occurrence were also examined. Larger changes in the frequency of occurrence of the produced cloud regimes were found for a regime associated to alto- and nimbo-type clouds and for a regime connected to shallow cumulus clouds and fog (\u22120.65% and +0.70% for the time period of the study, respectively).<\/jats:p>","DOI":"10.3390\/rs14215548","type":"journal-article","created":{"date-parts":[[2022,11,4]],"date-time":"2022-11-04T04:00:51Z","timestamp":1667534451000},"page":"5548","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["CRAAS: A European Cloud Regime dAtAset Based on the CLAAS-2.1 Climate Data Record"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0231-6298","authenticated-orcid":false,"given":"Vasileios","family":"Tzallas","sequence":"first","affiliation":[{"name":"Leibniz Institute for Tropospheric Research (TROPOS), Remote Sensing of Atmospheric Processes, Permoserstra\u00dfe 15, 04318 Leipzig, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1424-4546","authenticated-orcid":false,"given":"Anja","family":"H\u00fcnerbein","sequence":"additional","affiliation":[{"name":"Leibniz Institute for Tropospheric Research (TROPOS), Remote Sensing of Atmospheric Processes, Permoserstra\u00dfe 15, 04318 Leipzig, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5449-0701","authenticated-orcid":false,"given":"Martin","family":"Stengel","sequence":"additional","affiliation":[{"name":"Deutscher Wetterdienst (DWD), Frankfurter Str. 135, 63067 Offenbach am Main, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6682-5062","authenticated-orcid":false,"given":"Jan Fokke","family":"Meirink","sequence":"additional","affiliation":[{"name":"Royal Netherlands Meteorological Institute (KNMI), R&D Satellite Observations, 3731 GA De Bilt, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nikos","family":"Benas","sequence":"additional","affiliation":[{"name":"Royal Netherlands Meteorological Institute (KNMI), R&D Satellite Observations, 3731 GA De Bilt, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9308-3823","authenticated-orcid":false,"given":"J\u00f6rg","family":"Trentmann","sequence":"additional","affiliation":[{"name":"Deutscher Wetterdienst (DWD), Frankfurter Str. 135, 63067 Offenbach am Main, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andreas","family":"Macke","sequence":"additional","affiliation":[{"name":"Leibniz Institute for Tropospheric Research (TROPOS), Remote Sensing of Atmospheric Processes, Permoserstra\u00dfe 15, 04318 Leipzig, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2082","DOI":"10.1029\/2003GL018367","article-title":"Objective identification of cloud regimes in the Tropical Western Pacific","volume":"30","author":"Jakob","year":"2003","journal-title":"Geophys. 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