Past GCSS BLCWG cases

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Stratocumulus to shallow cumulus transitions

EUCLIPSE-GCSS Intercomparison of Large-Eddy and Single-Column Models

• Case coordinators: Stephan de Roode at the Delft University of Technology and Irina Sandu and Bjorns Stevens at MPI
• There are two separate cases with the following specifications:
  • ASTEX Lagrangian
  • Composite cases
• First discussions of results is alongside the EUCLIPSE meeting in September 2010, with more results and discussion at the June 2011 Exeter joint meeting with CFMIP and EUCLIPSE
• de Roode et al (2016): Shallow cumulus cloud control on the stratocumulus lifetime: LES results of EUCLIPSE/GASS Lagrangian stratocumulus transitions
• Neggers et al (2017): Single-column model simulations of subtropical marine boundary-layer cloud transitions under weakening inversions

CGILS BL cloud climate change response

CFMIP-GCSS Intercomparison of Large-Eddy and Single-Column Models

• Case coordinator: Minghua Zhang of Stony Brook University, NY
• Case specifications.
• First discussions of results at the joint meeting with CFMIP, 8th - 12th June 2009, at the University of British Columbia in Vancouver
• Focussed workshops 1st-2nd March 2010 and 29th-30th Sept 2010
• Summary of progress written up in May 2010 GEWEX news article
• Further discussion at the June 2011 Exeter joint meeting with CFMIP and EUCLIPSE
• Zhang et al (2013): CGILS: First Results from an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in General Circulation Models
• Blossey et al (2013): Marine low cloud sensitivity to an idealized climate change: The CGILS LES intercomparison
• Blossey et al (2016): CGILS Phase 2 LES intercomparison of response of subtropical marine low cloud regimes to CO2 quadrupling and a CMIP3 composite forcing change

Radiation intercomparison study

EUCLIPSE intercomparison study of radiative fluxes in stratocumulus

• Case coordinator: Sara Dal Gesso at KNMI
• Case description: the main objective is to quantify the intermodel spread in albedo for typical marine stratocumulus arising purely from the radiative transfer code.
• First discussion of results will be at the CFMIP/GCSS/EUCLIPSE Meeting on Cloud Processes and Climate Feedbacks , The Met Office, Exeter, United Kingdom, 6th-10th June, 2011.

RICO: precipitating trade cumulus. Sept 2006, GISS, New York

Case coordinators: Margreet van Zanten (LES) and A. Pier Siebesma (SCM) of KNMI.
• Case specifications.
• All presentations from GCSS/GPCI/RICO workshop at GISS, New York, Sept. 2006, including preliminary results from RICO case and RICO observational presentations.
• vanZanten et al (2011) : controls on precipitation and cloudiness in simulations of trade-wind cumulus as observed during RICO, JAMES (pdf)

DYCOMS RF02 nocturnal drizzling stratocumulus case. May 2005, Athens.

Case coordinators Andy Ackerman of NASA/Goddard (LES) and Matt Wyant of U. Washington (SCM).
• LES and SCM case specifications/results.
• Talks from pan-GCSS BLCWG session.
• Update presentation of the DYCOMS precipitation case at the GCSS-BLCWG meeting Sept 2006 in New York.
• Ackerman, A.S. and coauthors, 2009: Large-eddy simulations of a drizzling, stratocumulus-topped marine boundary layer. Mon. Wea. Rev. 137, 1083-1110
• Wyant,M.C. and coauthors, 2007: A single-column model intercomparison of a heavily drizzling stratocumulus-topped boundary layer, J. Geophys. Res., 112, D24204, doi:10.1029/2007JD008536.

Nocturnal nonprecipitating stratocumulus off the California coast during DYCOMS RF01. Nov. 2003, Broomfield, Colorado, USA

• LES case description/instructions/results. Case coordinator: Bjorn Stevens
• SCM case description/instructions/results.  Case coordinators: Martin Koehler, ECMWF and Ping Zhu, U. Washington.
• Stevens, B., and coauthors, 2005: Observations of nocturnal marine stratocumulus as represented by large eddy simulation. Mon. Wea. Rev., 133, 1443-1462.  Full text copy.
• Zhu, P., and coauthors, 2005: Intercomparison and interpretation of single column model simulations of a nocturnal stratocumulus topped marine boundary layer. Mon. Wea. Rev., 133, 2741-2758. Full text copy.

EUROCS FIRE-I Sc diurnal cycle intercomparison. Aug. 2002, Madrid, Spain.

• Case description/instructions/results. Case coordinator: Peter Duynkerke, KNMI (deceased)
• Duynkerke et al., 2004 : Observations and numerical simulations of the diurnal cycle of the EUROCS stratocumulus case. Quart. J. Royal Meteorol. Soc., 130, 3269-3298.

Continental shallow cumulus boundary layer diurnal cycle (ARM Oklahoma site). Jan. 2000, Boulder, Colorado, USA

• Case coordinator: Andy Brown, Met Office, UK
• A compressed file containing the submitted LES data is here .
• Brown et al., 2002:  Large-eddy simulation of the diurnal cycle of shallow cumulus convection over land. Quart. J. Roy. Meteor.  Soc., 128, 1075-1093.  Full text copy.
• EUROCS single-column model intercomparison study for this case.

Transitional trade cumulus case from ATEX. Aug. 24-26, 1998, Madrid, Spain

• Case coordinator: Bjorn Stevens, UCLA
• B. Stevens et al., 2000: Simulations of trade-wind cumuli under a strong inversion, J. Atmos. Sci, 58,1870-1891.   Full text copy.
• Case summary, goals, specifications and results
• Animation of simulated cloud field, from 7-8 hours into an ATEX simulation, and one with a smaller subgridscale turbulent mixing length which generates a much larger cloud fraction near the inversion (courtesy Andy Ackerman of NASA/Ames).

BOMEX Trade cumulus case. July 1997, Seattle, WA, USA

• Case Coordinator: Pier Siebesma, KNMI, Netherlands
• Siebesma, A. P., and coauthors, 2003: A large-eddy simulation intercomparison study of shallow cumulus convection. J. Atmos. Sci., 60, 1201-1219.  Full text copy.
• Case summary and goals, detailed case specifications, and preliminary results.
• Animation of cloud top heights from a BOMEX trade cumulus simulation on an approximately 25 by 25 km domain using 256x256x72 gridpoints and a 100 m horizontal and 50 m vertical grid spacing, made by Dave Stevens of Lawrence Berkeley Labs. Blue cloudtops are at 600 m, just above the subcloud lifted condensation level, and red corresponds to about 2 km cloud tops. Note range of cloud top heights.

Drizzle/no drizzle LES intercomparison, based on ASTEX Lagrangian 1. August 1996, Clermont-Ferrand, France

• Case Coordinator: Peter Duynkerke (deceased)
• Case summary, goals, specifications and results are not available.
• Related observations from Stephan de Roode of IMAU, including references.

ASTEX Lagrangians, August 1995, De Bilt, Netherlands

• Case coordinators: Steve Krueger, Univ. of Utah, USA, and Chris Bretherton, Univ. of Washington, USA.
• Bretherton, C. S., S. K. Krueger, M. C. Wyant, P. Bechtold, E. van Meijgaard, B. Stevens, and J. Teixeira, 1999: A GCSS boundary layer model intercomparison study of the first ASTEX Lagrangian experiment. Bound.-Layer Meteor., 93, 341-380. Full text copy.
• ASTEX Lagrangians modellers data set
• Case summary, goals, and specifications

Smoke cloud case. August 1995, De Bilt, Netherlands

• Case coordinators: Malcolm MacVean, Met Office, UK and Chris Bretherton, Univ. of Washington, USA.
• Bretherton, C. S., M. K. MacVean, and 14 coauthors, 1999: An intercomparison of radiatively-driven entrainment and turbulence in a smoke cloud, as simulated by different numerical models. Quart. J. R. Meteor. Soc., 125, 391-423.  Full text copy.
• Case summary, goals, and specifications

Nocturnal subtropical stratocumulus case. August 1994, Boulder, Colorado, USA

• Case coordinator: Chin-Hoh Moeng, NCAR, USA
• Moeng, C.-H., and coauthors, 1996: Simulation of a stratocumulus-topped PBL: Intercomparison among different numerical codes. Bull. Amer. Meteor. Soc., 77, 261-278. Full text copy.
• Bechtold, P., and coauthors, 1996: Modeling a stratocumulus-topped PBL: Intercomparisons among different 1D codes and with LES. Bull. Amer. Meteor. Soc., 77, 2033-2042.  Full text copy.

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Presentations from Lake Arrowhead Workshop on the Planetary Boundary Layer, 14-16 June 2005. Many GCSS BLCWG participants attended this excellent workshop, though it was not formally a GCSS event.