Climate Dynamics

, Volume 39, Issue 11, pp 2713–2731 | Cite as

The representation of tropical upper tropospheric water in EC Earth V2

  • M. S. JohnstonEmail author
  • P. Eriksson
  • S. Eliasson
  • C. G. Jones
  • R. M. Forbes
  • D. P. Murtagh


Tropical upper tropospheric humidity, clouds, and ice water content, as well as outgoing longwave radiation (OLR), are evaluated in the climate model EC Earth with the aid of satellite retrievals. The Atmospheric Infrared Sounder and Microwave Limb Sounder together provide good coverage of relative humidity. EC Earth’s relative humidity is in fair agreement with these observations. CloudSat and CALIPSO data are combined to provide cloud fractions estimates throughout the altitude region considered (500–100 hPa). EC Earth is found to overestimate the degree of cloud cover above 200 hPa and underestimate it below. Precipitating and non-precipitating EC Earth ice definitions are combined to form a complete ice water content. EC Earth’s ice water content is below the uncertainty range of CloudSat above 250 hPa, but can be twice as high as CloudSat’s estimate in the melting layer. CERES data show that the model underestimates the impact of clouds on OLR, on average with about 9 W m−2. Regionally, EC Earth’s outgoing longwave radiation can be ∼20 W m−2 higher than the observation. A comparison to ERA-Interim provides further perspectives on the model’s performance. Limitations of the satellite observations are emphasised and their uncertainties are, throughout, considered in the analysis. Evaluating multiple model variables in parallel is a more ambitious approach than is customary.


Humidity Clouds IWC Tropics Climate Satellite 



The authors would like to thank Klaus Wyser (SMHI), Simona Ştefănescu (ECMWF) for their aid in setting up and running the model. Special thanks to George E. Ferriter for his linguistic critique of the article. The CERES data are obtained from the NASA Langley Research Centre EOSDIS Distributed Archive Center. Discussions with Norman Loeb and Dave Doelling were beneficial. We would like to thank the following organisations for their open access to the data used in this study: GSFC Earth Science Data and Information Services Center (GES DISC), the Jet Propulsion Laboratory, CloudSat Data Processing Center, and ISCCP, and IPSL/LMD for CALIPSO-GOCCP dataset available at


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • M. S. Johnston
    • 1
    • 2
    Email author
  • P. Eriksson
    • 1
  • S. Eliasson
    • 3
  • C. G. Jones
    • 2
  • R. M. Forbes
    • 4
  • D. P. Murtagh
    • 1
  1. 1.Department of Earth and Space SciencesChalmers University of TechnologyGöteburgSweden
  2. 2.Swedish Meteorological and Hydrological Institute (SMHI)NorrköpingSweden
  3. 3.Department of Computer Science, Electrical and Space EngineeringLuleå University of TechnologyKirunaSweden
  4. 4.ECMWFReading, BerkshireUK

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