A recent assessment of the state of global cloudiness in the satellite-based climate data records

 

Four decades of satellite-based observations of clouds are now available and there are currently four different global cloud climate data records (CDRs) available providing 35+ years of data from the passive imagers, namely CLARA-A3, ESA Cloud CCI, ISCCP and PATMOS-X. This contribution presents a comprehensive assessment of the latest versions of these four long-term cloud CDRs. Given the fact that clouds cover nearly 70% of our planet and exert strong control on the radiation budget through their effects on radiation, precipitation, circulation and through their susceptibility to aerosols, such a periodic observational assessment of their global state is necessary from the climate perspective. CLARA-A3, PATMOS-X and ISCCP have been improved considerably in the recent years, thanks mainly to improved calibration, better training, algorithm developments, and rigorous validations.

This contribution will focus on three main areas:

1) Presenting the state-of-the-art global climatologies of cloud properties from the said CDRs, while highlighting the agreements and disagreements among them.

2) Evaluating the decadal stability of cloudiness in these CDRs using CALIPSO and MODIS as the references in light of the stringent requirements set by the WMO Global Climate Observing Systems (GCOS).

3) Investigating the robust trends in global cloudiness and their commonalities across the CDRs.