Land shallow cumulus convection (ARM)
Case description
The ARM Cumulus (ARMCU) case simulates a diurnal cycle of shallow cumulus convection over the ARM (Atmospheric Radiation Measurement) Southern Great Plains site. This is a classic case for testing cumulus parameterization and LES modeling of continental shallow convection. The case exists in two configurations: 1D (single column) and 3D (LES).
Warning
The 3D configuration requires MPI parallelization and the 1D configuration can only be run on a single core.
Configuration
Parameter |
1D (ARMCU_1D_CONDSAMP) |
3D (ARMCU_LES) |
|---|---|---|
Category |
Idealized cases |
HPC cases |
Dynamics |
3D with 1D turbulence |
3D LES |
Horizontal grid spacing |
40000 m (1x1) |
500 m (64x64) |
Integration length |
54000 s (15 hours) |
43200 s (12 hours) |
Time step |
100 s |
2 s |
Coriolis effect |
enabled |
enabled |
Turbulence |
TKEL (1D) |
TKEL (3D) |
Cloud scheme |
ICE3 |
ICE3 |
Deep convection |
NONE |
NONE |
Shallow convection |
EDKF |
NONE |
Radiation |
NONE |
NONE |
LES diagnostics |
enabled |
enabled |
Declination
Configuration |
Turbulence |
Grid |
|---|---|---|
ARMCU_1D_CONDSAMP |
TKEL (BL89) |
1x1 |
ARMCU_LES/HM21 |
TKEL (HM21) |
64x64 |
ARMCU_LES/DEAR |
TKEL (DEAR) |
64x64 |
Steps
Step |
Script |
|---|---|
001_prep_ideal |
run_prep_ideal_case_xyz / run_prep_ideal |
002_mesonh |
run_mesonh_xyz / run_mesonh |
Specificities
Scientific specificities
Idealized forcing using time-varying surface fluxes (heat, moisture, momentum)
Surface latent heat flux switches from positive to negative during the transition from daytime heating to nighttime cooling
Deep large-scale forcing from ARM field campaign data
Conditional sampling (CONDSAMP) enabled with 3 sample levels for cloud statistics
LES diagnostics with time-averaging from 3600s to 43200s (12h daytime period)
Technical specificities
1D: Cartesian flat domain with single point (NIMAX=1, NJMAX=1), 100 vertical levels
3D: 64x64 horizontal grid, 100 vertical levels with 40m spacing
Model top at 1000m
Initialization from ARM SGP sounding (June 21, 1997)
Cyclic boundary conditions for 3D
Validation
Vertical profiles of mean quantities: MEAN_RC, MEAN_RR, MEAN_U, MEAN_V, MEAN_W, MEAN_THL
Subgrid flux profiles: SBG_WTHL, SBG_WRT
Total water and mass flux: MEAN_RT, MEAN_MF
Cloud fraction validation at different levels
Numerical ressources
1D: Single CPU (1 node, 1 core) 3D: 2 nodes, 128 cores (MPI parallel)
References
Brown, A.R., et al. (1999): Large-Eddy Simulation of Atmospheric Boundary Layer, BLM, 91, 271-289.
Xu, K.M., and D.K. Araker (1995): The behavior of macrophage-like cells in small cumulus clouds. J. Atmos. Sci., 52, 2923-2942.