GEWEX Cloud System Study - Working Group 4

WG4 Model Intercomparison Projects

Case 1: Tropical oceanic squall line

Two- and three-dimensional modeling of a squall line on a time scale of a few hours. The initial conditions and evaluation data sets were obtained as part of an intensive observation period in TOGA COARE.

Case 1 description and results

Paper on cloud-resolving model intercomparison results

Paper on single-column model intercomparison results

Leader: Jean-Luc Redelsperger

Case 2: Tropical oceanic deep convection

Two- and three-dimensional modeling of the evolution of convection subjected to observed, time-dependent, large-scale forcing on a time scale of a week. Initial conditions for the simulations, the evolving large-scale forcing and the data used in model evaluation are averages over the TOGA COARE Intensive Flux Array (IFA).

Case 2 description and results

Leader: Steve Krueger

Case 2 radiation code offline intercomparison

The purpose of this exercise is to examine and compare the surface heat fluxes, radiative heating rates and fluxes, and microphysical fields from the CRM and SCM models at one instant of time during the Case 2 period.

Description

Leaders: Wei-Kuo Tao and Dan Johnson

Case 3: Continental deep convection

This model intercomparison case involves two new aspects:

• It is a continental case based on intensive measurements taken at the Dept of Energy's ARM (Atmospheric Radiation Measurement program) Southern Great Plains experimental site during June and July 1997. The millimeter cloud radar (MMCR) was operational during this time and has provided profiles of cloud fraction. The ARM SGP site also has a very extensive array of other meteorological instruments.
• It is being done in collaboration with the ARM Single Column Modeling Group. This has brought in more SCMers and the support of the ARM DSIT (Data and Science Integration Team) to provide the forcing and evaluation data and to compile the results submitted by the modelers.

Case 3 description and results

Leaders: Steve Krueger and Kuan-Man Xu

EUROCS (EUROpean Cloud Systems):

The project EUROCS aims to improve the treatment of cloud systems in global and regional climate models. EUROCS concentrates its efforts on four major and well identified deficiencies of climate models: i) stratocumulus over ocean, ii) diurnal cycle of cumulus, iii) diurnal cycle of precipitating deep convection over continents, and iv) sensitivity of deep convection development to the moisture profile. The last two areas (diurnal cycle of deep convection, led by Francoise Guichard and Jon Petch, and sensitivity of deep convection to the moisture profile, led by Stephen Derbyshire) are part of WG4 activities.

See the EUROCS web page for case descriptions and results.

Proposed Case 4: Daytime convective development over land: an idealized
case based on TRMM-LBA observations.

Wojciech W. Grabowski, NCAR
(with data provided by Steve Lang, NASA Goddard)

The purpose of this case is to investigate the development of the daytime convective boundary layer over land and the transition from shallow to deep convection.

Case 4 description

Procedures to submit Case 4 results

Example of Results

Results from benchmark set of simulations