Climate Dynamics

, Volume 43, Issue 7–8, pp 1753–1772

Sensitivity of the regional climate model RegCM4.2 to planetary boundary layer parameterisation

  • Ivan Güttler
  • Čedo Branković
  • Travis A. O’Brien
  • Erika Coppola
  • Branko Grisogono
  • Filippo Giorgi
Article

DOI: 10.1007/s00382-013-2003-6

Cite this article as:
Güttler, I., Branković, Č., O’Brien, T.A. et al. Clim Dyn (2014) 43: 1753. doi:10.1007/s00382-013-2003-6

Abstract

This study investigates the performance of two planetary boundary layer (PBL) parameterisations in the regional climate model RegCM4.2 with specific focus on the recently implemented prognostic turbulent kinetic energy parameterisation scheme: the University of Washington (UW) scheme. When compared with the default Holtslag scheme, the UW scheme, in the 10-year experiments over the European domain, shows a substantial cooling. It reduces winter warm bias over the north-eastern Europe by 2 °C and reduces summer warm bias over central Europe by 3 °C. A part of the detected cooling is ascribed to a general reduction in lower tropospheric eddy heat diffusivity with the UW scheme. While differences in temperature tendency due to PBL schemes are mostly localized to the lower troposphere, the schemes show a much higher diversity in how vertical turbulent mixing of the water vapour mixing ratio is governed. Differences in the water vapour mixing ratio tendency due to the PBL scheme are present almost throughout the troposphere. However, they alone cannot explain the overall water vapour mixing ratio profiles, suggesting strong interaction between the PBL and other model parameterisations. An additional 18-member ensemble with the UW scheme is made, where two formulations of the master turbulent length scale in unstable conditions are tested and unconstrained parameters associated with (a) the evaporative enhancement of the cloud-top entrainment and (b) the formulation of the master turbulent length scale in stable conditions are systematically perturbed. These experiments suggest that the master turbulent length scale in the UW scheme could be further refined in the current implementation in the RegCM model. It was also found that the UW scheme is less sensitive to the variations of the other two selected unconstrained parameters, supporting the choice of these parameters in the default formulation of the UW scheme.

Keywords

Eddy heat diffusivity Structural uncertainty RegCM Systematic errors 

Supplementary material

382_2013_2003_MOESM1_ESM.doc (726 kb)
Supplementary material 1 (DOC 726 kb)
382_2013_2003_MOESM2_ESM.doc (4.2 mb)
Supplementary material 2 (DOC 4,324 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Ivan Güttler
    • 1
  • Čedo Branković
    • 1
  • Travis A. O’Brien
    • 2
  • Erika Coppola
    • 3
  • Branko Grisogono
    • 4
  • Filippo Giorgi
    • 3
  1. 1.Croatian Meteorological and Hydrological Service (DHMZ)ZagrebCroatia
  2. 2.Earth Sciences DivisionLawrence Berkeley National LabBerkeleyUSA
  3. 3.Earth System Physics SectionInternational Centre for Theoretical Physics (ICTP)TriesteItaly
  4. 4.Department of Geophysics, Faculty of ScienceUniversity of ZagrebZagrebCroatia

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