The Global Energy and Water Exchanges (GEWEX) Cloud Assessment (2005-2012, Stubenrauch et al. 2013) provided the first coordinated intercomparison of publically available, standard global cloud products (gridded, monthly statistics).

The GEWEX Cloud Assessment database, created by the participating teams, contains many cloud properties: their monthly means, variability and distributions within gridboxes of 1° latitude x 1° longitude and is available at

In addition to self-assessments (Annex I of Stubenrauch et al. 2012) which show the maturity of the various datasets, the analyses have shown how cloud properties are perceived by instruments measuring different parts of the electromagnetic spectrum and how cloud property averages and distributions are affected by instrument choice as well as some methodological decisions.

Since then, several teams have improved their datasets, and new global long-term datasets emerged.

Therefore, the GEWEX Data and Analysis Panel foresees an update of this cloud data base, which is actually in preparation and will be available on this website in 2020. The updated cloud data base will contain data until 2018, and updates are foreseen once per year.


Analyzed cloud properties

  • Cloud amount (CA)
  • Effective CA (CAE)
  • Cloud pressure (CP)
  • Cloud temperature (CT)
  • Cloud altitude (CZ)
  • Cloud optical depth (COD)
  • Cloud IR emissivity (CEM)
  • Cloud phase (ice/water)
  • Ice water path (CIWP)
  • Liquid water path (CLWP)
  • Effective particle radius: CREI (ice), CREW (water)