CLARA-A 2 : The second edition of the CM SAF cloud and 1 radiation data record from 34 years of global AVHRR data 2 3

14 The second edition of the satellite-derived climate data record CLARA (“The CM SAF cLoud, Albedo and 15 surface RAdiation dataset from AVHRR data” second edition denoted CLARA-A2) is described. The data 16 record covers the 34-year period from 1982 until 2015 and consists of cloud, surface albedo and surface 17 radiation budget products derived from the AVHRR (Advanced Very High Resolution Radiometer) sensor 18 carried by polar-orbiting, operational meteorological satellites. The data record is produced by the EUMETSAT 19 Climate Monitoring Satellite Application Facility (CM SAF) project as part of the operational ground segment. 20 Its upgraded content and methodology improvements since edition 1 are described in detail as well as some 21 major validation results. Some of the main improvements of the data record come from a major effort in cleaning 22 and homogenising the basic AVHRR level 1 radiance record and a systematic use of CALIPSO-CALIOP cloud 23 information for development and validation purposes. Examples of applications studying decadal changes in 24 ArcticPolar sSummer surface albedo and cloud conditions, as well as global cloud redistribution patterns, are 25 provided. 26 27