GABLS-4 : GEWEX Atmospheric Boundary Layer Study

SCM/LSM and LES intercomparison at DomeC (Antarctic Plateau)

E. Bazile (1), F. Couvreux(1), P. Le Moigne(1), C. Genthon (2),

O. Traullé(1*), W. Maurel(1), H. Barral(3), G. Canut(1), A.A.M. Holtslag(4), G. Svensson(5)

(1) Météo-France, CNRM/GAME, Toulouse, France (eric.bazile_at_meteo.fr)

(2) LGGE UMR 5183, Grenoble 38401 France

(1*) Météo-France, DSO, Toulouse, France

(3) LTHE/CNRS, Grenoble, 38401 France

(4) Meteorology and Air Quality Section, Wageningen University, the Netherlands,

(5) Department of Meteorology and Bert Bolin Centre for Climate Research, Stockholm University, Stockholm





From O. Traullé (left) and E. Brun (right)

Introduction :

Within GABLS (GEWEX Atmospheric Boundary Layer Study), inter-comparison studies are carried on for boundary layer parameterizations schemes in use by numerical weather prediction and climate models. Under stable stratifications, models still have large biases, which depend on the parameterizations used for boundary layer and for surface (Holtslag et al, 2013, BAMS). The first three GABLS inter-comparison studies (Cuxart et al. 2006, Svensson et al 2011, Bosveld et al 2014) dealt only with moderate stable conditions. (GABLS)

In the GABLS4 case, the aim is to study the interaction of a boundary layer with strong stability (Ri>>1) with a surface with a low conductivity and a high cooling potential, such as snow (glacier), it is easier to initialize as there is no need of soil moisture, vegetation type or soil characteristics. The case is based on a real case, the starting date is the 11th, Dec 2009 at 00UTC. Such a case is explored using observations at the Antarctic Plateau at DomeC. This intercomparison concerns Land-Snow Surface Models, Single Column Models and Large Eddy Simulations

Initial Case description

Updates :

- 18 Aug. 2014: correction of the reference height in the NetCdf file : driver_stage0 . 3.3m above the surface instead of 4.6m in the previous version.
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16 Sept. 2014 : Thanks to G. Balsamo the driver_stage0 file has been updated with exactly the same format and order as the one used in DICE. All the fields are exactly the same. The driver_stage1 has been also updated following the discussion we had during the GEWEX conference. The snow density profile and a more detailed temperature profile in the snow pack have been added in the file valid for the 11th Dec..2009
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06 Nov 2014 : Surface pressure correction in driver_stage1 : Ps=65100 pa value prescribed in driver_stage0 (instead of 64600 pa. )
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20 Nov 2014 : Units correction in driver_stage1 : temperature advection in K/s and humidity advection Kg/Kg/s
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25 Feb 2015 : Driver stage 2 and 3, specifications for LES are now available driver_stage2 , driver_stage3 and LES_specifications for stage 2 and 3
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20-22 May 2015 : Common GABLS4/DICE workshop at Météo-France Toulouse
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June 2015 : Additional simulations for the 1st October 2015:description
- 26 October 2016 : New simulations based on a “shorten ideal case” focussing only on the stable part : deadline 15th December 2016 :description

Events & presentations:

- Summer 2014 : GABLS4 Announcement during the GEWEX conference in July 2014 and during the World Weather Open Science Conference (WWOSC) in Montreal (GABLS4 presentation)
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20-22 May 2015 : Common GABLS4/DICE workshop at Météo-France Toulouse
- August 2015 : Summary of the Toulouse workshop Gewex Newsletter pp18-19
- 20-24 June 2016 : 22nd Symposium on Boundary Layers and Turbulence Salt Lake City (USA):
- Presentation on GABLS4 E. Bazile et al.
- Poster on LES results F. Couvreux et al.

For participants only: not yet open

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Acknowledgements :

This work is supported by the french national program LEFE/INSU(2015-2017)

The meteorological profiling observation program at Dome C which provides 40+ m data for model evaluation / validation for GABLS4, is supported by IPEV (program CALVA), CNRS/INSU (program CLAPA) and OSUG (program CENACLAM). The IPY-CONCORDIASI program, supported by CNES, IPEV and CNRS, provided radiosonde data.

Special thanks to Vincent Guidard (Météo-France,CNRM/GAME) for the 4Dvar re-analysis done with the ARPEGE configuration used during the Concordiasi experiment. Furthermore, the people responsible of the observations at DomeC and those who provided the data for the chosen period : Eric Aristidi (Laboratoire Lagrange, Université Nice Sophia Antipolis, France), Christian Lanconelli (ISAC/CNR, Italy), Ghislain Picard and Laurent Arnaud (LGGE, Grenoble, France), Andrea Pellegrini (ENEA, Italy) and Laura Genoni. We also thanks Etienne Vignon (LGGE), William Maurel (Météo-France,CNRM/GAME), Eric Brun (Météo-France,CNRM/GAME) and not forgetting Irina Sandu (ECMWF) as a most valuable beta tester for the atmospheric forcing used in the SCM.