Articles | Volume 17, issue 9
Atmos. Chem. Phys., 17, 5809–5828, 2017
Atmos. Chem. Phys., 17, 5809–5828, 2017

Research article 11 May 2017

Research article | 11 May 2017

CLARA-A2: the second edition of the CM SAF cloud and radiation data record from 34 years of global AVHRR data

Karl-Göran Karlsson1, Kati Anttila2, Jörg Trentmann3, Martin Stengel3, Jan Fokke Meirink4, Abhay Devasthale1, Timo Hanschmann3, Steffen Kothe3, Emmihenna Jääskeläinen2, Joseph Sedlar1, Nikos Benas4, Gerd-Jan van Zadelhoff4, Cornelia Schlundt3, Diana Stein3, Stefan Finkensieper3, Nina Håkansson1, and Rainer Hollmann3 Karl-Göran Karlsson et al.
  • 1Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden
  • 2Finnish Meteorological Institute (FMI), Helsinki, Finland
  • 3Deutscher Wetterdienst (DWD), Offenbach, Germany
  • 4Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands

Abstract. The second edition of the satellite-derived climate data record CLARA (The CM SAF Cloud, Albedo And Surface Radiation dataset from AVHRR data – second edition denoted as CLARA-A2) is described. The data record covers the 34-year period from 1982 until 2015 and consists of cloud, surface albedo and surface radiation budget products derived from the AVHRR (Advanced Very High Resolution Radiometer) sensor carried by polar-orbiting, operational meteorological satellites. The data record is produced by the EUMETSAT Climate Monitoring Satellite Application Facility (CM SAF) project as part of the operational ground segment. Its upgraded content and methodology improvements since edition 1 are described in detail, as are some major validation results. Some of the main improvements to the data record come from a major effort in cleaning and homogenizing the basic AVHRR level-1 radiance record and a systematic use of CALIPSO-CALIOP cloud information for development and validation purposes. Examples of applications studying decadal changes in Arctic summer surface albedo and cloud conditions are provided.

Short summary
The paper presents the second version of a global climate data record based on satellite measurements from polar orbiting weather satellites. It describes the global evolution of cloudiness, surface albedo and surface radiation during the time period 1982–2015. The main improvements of algorithms are described together with some validation results. In addition, some early analysis is presented of some particularly interesting climate features (Arctic albedo and cloudiness + global cloudiness).
Final-revised paper