Post on 20-Jan-2016
Bogdan Rosa1, Marcin Kurowski1, Damian Wójcik1, and Michał Ziemiański1
Acknowledgements: Oliver Fuhrer2, Zbigniew Piotrowski1,3
1. Institute of Meteorology and Water Management
2. Meteo Swiss
3. National Center for Atmospheric Research
Recent progress in the anelastic branch
COSMO General Meeting, Rome, 5-9 September 2011
Outline
COSMO General Meeting, Rome, 5-9 September 2011
Testing of the EULAG dynamical core for realistic flows over the Alpine topography with simplified physics parameterization
Coupling of EULAG dynamical core with COSMO via an interface
Technical testing of the coupled model by idealized cases
Testing the EULAG core for Alpine flows - a convection case study
COSMO General Meeting, Rome, 5-9 September 2011
Task 1.3: Tests of the EULAG dynamical core for realistic flows over the Alpine topography with simplified physics parameterization
To simulate realistic flows over the Alpine topography, with resolution ranging from 2.2, 1.1 km to 0.55 km, applying simplified parameterizations of basic subgrid processes. Compare results between EULAG and COSMO simulations.
Moist processes are only simulated on explicit grid (i.e. no shallow convection parameterization, no moist turbulence) with a simple microphysics (Kessler-scheme) in both models. Turbulent diffusion with a one-equation (TKE)-model (not necessarily the same in both models) without interactive parameterization, but using the surface and radiation fluxes from independent COSMO 2.2 km model runs (or simplified surface fluxes)
COSMO General Meeting, Rome, 5-9 September 2011
Description of the experiments
Experiments involve case study of summer Alpine convection on 12 July 2006.
Simplified parameterizations:• Boundary layer processes are represented by TKE (turbulent kinetic energy) model.• Surface fluxes and drag taken from the operation run of COSMO2 model for Switzerland.• Simple representation of moist processes (warm rain Kessler-scheme)
Experiment setup:• Horizontal resolution 1.1 km, vertical resolution as in COSMO2• The computational domain is restricted to 234x198 km and covers the Southern Alps• Initial, boundary conditions from COSMO2 operational run
General meteorological situation in the Alpine region - 12 July 2006
MSG (Meteosat Second Genertion) 12:00 UTC
Synoptic situation in the area: slow-moving cold front in a shallow surface trough of low pressure
Synoptic map – 2:00 UTC, 12 July 2006
This is representative case study for summer (convective) situations.
COSMO General Meeting, Rome, 5-9 September 2011
COSMO General Meeting, Rome, 5-9 September 2011
Diurnal cycle of potential temperature at the ground. Results from COSMO and EULAG experiments.
COSMO General Meeting, Rome, 5-9 September 2011
Time evolution of cloud water and stream lines from EULAG simulation.
12:00 UTC14:00 UTC
16:00 UTC 18:00 UTC
Comparison of the EULAG simulation with satellite images
12:00 UTC
15:00 UTC
12:00 UTC
15:00 UTC
Temporal and spatial structure of the simulated convection in the EULAG experiment closely resembles the actual development
COSMO General Meeting, Rome, 5-9 September 2011
Realization of the CDC plan – coupling
COSMO General Meeting, Rome, 5-9 September 2011
CDC Project Plan
Task 1.6: Coupling of EULAG dynamical core with COSMO via an interface.
To better compare the behavior of the new dynamical core in more realistic model applications with full physics parameterizations, the dynamical core of EULAG will be coupled with the COSMO-model. As an intermediate step and to keep the amount of work in a reasonable range this will be done via an interface.
This means that the EULAG dyn. core keeps his own variables, data structure, etc. It is not the aim to have a very efficient code version at this stage but to have a useable model version.
EULAG in Fortran 90
COSMO General Meeting, Rome, 5-9 September 2011
Migration of F77 EULAG code into F90
Dynamic memory allocation (ALLOCATE/DEALLOCATE), no COMMON blocks, no DATA and BLOCKDATA statements
Modularization (data and source code separation, logical code decomposition into specialized modules)
Fortran 90 language syntax (free format syntax, upper/lower cases, names and comments in English, COSMO-like code indentations, new operators (>, <, etc.), KIND argument for real and integer types, no GOTO instructions,...)
C&E coupling – plugging the new dynamical core in
COSMO General Meeting, Rome, 5-9 September 2011
A new configuration of EULAG dyn. core is done via namelists.
EULAG dynamical core is temporarily plugged instead of default R-K dynamical core in src_runge_kutta module. It uses a set of variables defined in data_eufields module.
In src_runge_kutta:
Sections 1-3a: unchanged(initial time step,
boundary tendencies, slow tendencies fromradiation, convection,
Rayleigh damping, etc.)
Sections 4a-6: unchanged (advection and diffusion
of scalars, saturation adjustment)
Sections 3b-3cR-K time
integration
EULAGtime
integration
COSMO fields to EULAG
beginof a time step
endof a time step
EULAG fields to COSMO
C&E coupling – parallelization
COSMO General Meeting, Rome, 5-9 September 2011
MPI communication is basically organized in COSMO (init_procgrid). A new subroutine (emulate_geomset) is used to initialize EULAG's MPI variables following COSMO structure. This ensures identical domain decomposition in both models, i.e. the same grid points lie on the same processor domain.
Domain decomposition in EULAG Single processor neighborhood
C&E coupling – grid adaptation
COSMO General Meeting, Rome, 5-9 September 2011
COSMO staggered C-grid and EULAG unstaggered A-grid
There are at least two options for distribution of vertical levels: 1) interpolation from COSMO to EULAG levels2) 1:1 transformation for mass levels with interpolation of the velocities only (operational?)
COSMO (1) (2)EULAG
dz
dz
dz
dz/2
dz/2
n levels n+1 levels n+2 levels
dom
ain
heig
ht
C&E coupling – data flow
COSMO General Meeting, Rome, 5-9 September 2011
Mutual data transfer between COSMO and EULAG
When data flow is required?1. at the initialization stage (to initialize EULAG dynamical core)2. at each time step
R-K integr.
EULAGintegr.
COSMO fields to EULAG
EULAG fields to COSMO
Sections 1-3a.
Sections 4a-6.
C-grid(u
C,v
C,w
C,T, p, forcings)
A-grid(u
E,v
E,w
E,Th, forcings)
(uC,v
C,w
C,T)
Realization of the CDC plan – testing C&E
COSMO General Meeting, Rome, 5-9 September 2011
Task 1.7: Technical testing with COSMO by idealised cases
The correct coupling of the EULAG dynamical core into COSMO can be at first tested with the implemented idealized test cases. This testing can be performed ‘by a press of a button’ in COSMO. The staff is now well trained with the idealized tests (see task 1.1), therefore it is not necessary to perform an extended analysis of such idealized tests, but simply to check if any technical coupling problems occur.
Performed tests:1. inertia-gravity wave (Skamarock and Klemp,
1994)2. cold density current (Straka et al., 1993)
Two dimensional time dependent simulation of inertia-gravity waves
COSMO General Meeting, Rome, 5-9 September 2011
Skamarock W. C. and Klemp J. B. Efficiency and accuracy of Klemp-Wilhelmson time-splitting technique. Mon. Wea. Rev. 122: 2623-2630, 1994
Initial potential temperature perturbation
Setup overview:
domain size 300x10 km resolution 1x1km, 0.5x0.5 km, 0.25x0.25 km rigid free-slip b.c. periodic lateral boundaries constant horizontal flow 20m/s at inlet no subgrid mixing hydrostatic balance stable stratification N=0.01 s-1
max. temperature perturbation 0.01K Coriolis force included
Constant ambient flow within channel 300 km and 6000 km long
km
km
outletinlet 220
/1
)/sin()0,,(
axx
Hztzx
c
Initial potential temperature perturbation
smtw
smtv
smtu
/0)0(
/0)0(
/20)0(
Initial velocity
COSMO General Meeting, Rome, 5-9 September 2011
Results - gravity waves in a short channel
EulagC&E
EulagC&E
EulagC&E
Comparison with analytical solution
COSMO General Meeting, Rome, 5-9 September 2011
Eulag
C&E
Analytical
Profiles of potential temperature along 5000m height
COSMO General Meeting, Rome, 5-9 September 2011
'
C&E
Analytical
Gravity waves in a long channel
COSMO General Meeting, Rome, 5-9 September 2011
Eulag
C&E
Eulag
C&E
Eulag
C&E
Gravity waves in a long channel
COSMO General Meeting, Rome, 5-9 September 2011
C&E
C&E
C&E
Analytical
Analytical
Analytical
COSMO General Meeting, Rome, 5-9 September 2011
Profiles of potential temperature along 5000m height
C&E
Analytical
COSMO General Meeting, Rome, 5-9 September 2011
Two dimensional time dependent simulation of cold blob descending to the ground
)300( Kconst
Straka, J. M., Wilhelmson, Robert B., Wicker, Louis J., Anderson, John R., Droegemeier, Kelvin K., Numerical solutions of a non-linear density current:A benchmark solution and comparison International Journal for Numerical Methods in Fluids, (17), 1993
free-slip b.c.
open b.c.
periodic b.c.periodic b.c.
r)(rTT
Experiment configuration:
• isentropic atmosphere, θ(z)=const (300K)• periodic lateral boundaries• free-slip bottom b.c.• constant subgrid mixing, K=75m2/s• domain size 51.2km x 6.4km• bubble min. temperature -15K• bubble size 8km x 4km• no initial flow• integration time 15min
COSMO General Meeting, Rome, 5-9 September 2011
Distribution of potential temperature after 900 sec
C&E inviscid 100m
C&E viscous – diffusive forcing from COSMO parameterizations100m
Comparison of the potential temperature distribution
COSMO General Meeting, Rome, 5-9 September 2011
C&E
Eulag
Cosmo100m
COSMO General Meeting, Rome, 5-9 September 2011
C&E
Eulag
Cosmo
Comparison of the horizontal and vertical velocities obtained from three different models
100m
Eulag
C&E
Cosmo100m
COSMO General Meeting, Rome, 5-9 September 2011
C&E
Eulag
Cosmo
Comparison of potential temperature distribution at resolution 25 m
25m
COSMO General Meeting, Rome, 5-9 September 2011
C&E
Eulag
Cosmo25m
C&E
Eulag
Cosmo25m
Comparison of the horizontal and vertical velocities obtained from three different models
1. MOTIVATION CONCLUSIONS
COSMO General Meeting, Rome, 5-9 September 2011
Temporal and spatial structure of the simulated convection in the EULAG experiment closely resembles the actual development.
EULAG code has been successfully implemented in COSMO. Results of the idealized tests obtained using the hybrid E&C
model are in good qualitative and quantitative agreement both with reference and analytical solutions.
Small differences indicate the need for further testing and verification of the E&C code.
Dynamical core of the developed prototype, cooperates correctly with the diffusive forcing from COSMO parameterizations.
Realization of the CDC plan – documentation of the already performed tasks.
COSMO General Meeting, Rome, 5-9 September 2011
B. Rosa, M. J. Kurowski, and M. Z. Ziemiański, 2011, Testing the anelastic nonhydrostatic model EULAG as a prospective dynamical core of a numerical weather prediction model. Part I: Dry Benchmarks, Acta Geophysica, 59 (6), DOI: 10.2478/s11600-011-0041-1. M. J. Kurowski, B. Rosa and M. Z. Ziemiański, 2011, Testing the anelastic nonhydrostatic model EULAG as a prospective dynamical core of numerical weather prediction model. Part II: Simulations of a supercell, Acta Geophysica, 59 (6), DOI: 10.2478/s11600-011-0051-z. M. Z. Ziemiański, M. J. Kurowski, Z. P. Piotrowski, B. Rosa and O. Fuhrer, 2011, Toward very high resolution NWP over Alps: Influence of the increasing model resolution on the flow pattern, Acta Geophysica, 59 (6), DOI: 10.2478/s11600-011-0054-9