The Next-Generation The Next-Generation Flexible Global Flexible Global Atmospheric Model Atmospheric Model Hann-Ming Henry Juang Hann-Ming Henry Juang Environmental Modeling Center, NCEP Environmental Modeling Center, NCEP Dynamics group: lead by H.-L. Pan Dynamics group: lead by H.-L. Pan M. Iredell, H. Juang, S. Moorthi, J. M. Iredell, H. Juang, S. Moorthi, J. Sela Sela Mentor: Don Johnson Mentor: Don Johnson Symposium on the 50th Anniversary of Operational Symposium on the 50th Anniversary of Operational Numerical Weather Prediction Numerical Weather Prediction June 17, 2004 June 17, 2004
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The Next-Generation Flexible Global Atmospheric Model
The Next-Generation Flexible Global Atmospheric Model. Hann-Ming Henry Juang Environmental Modeling Center, NCEP Dynamics group: lead by H.-L. Pan M. Iredell, H. Juang, S. Moorthi, J. Sela Mentor: Don Johnson Symposium on the 50th Anniversary of Operational Numerical Weather Prediction - PowerPoint PPT Presentation
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The Next-Generation Flexible The Next-Generation Flexible Global Atmospheric ModelGlobal Atmospheric Model
Hann-Ming Henry JuangHann-Ming Henry JuangEnvironmental Modeling Center, NCEPEnvironmental Modeling Center, NCEP
Dynamics group: lead by H.-L. PanDynamics group: lead by H.-L. PanM. Iredell, H. Juang, S. Moorthi, J. SelaM. Iredell, H. Juang, S. Moorthi, J. SelaMentor: Don JohnsonMentor: Don Johnson
Symposium on the 50th Anniversary of Operational Symposium on the 50th Anniversary of Operational
Reasons to develop new codeReasons to develop new code Flexible to test different dynamical coresFlexible to test different dynamical cores Develop to work with others, e.g. ESMFDevelop to work with others, e.g. ESMF
ContentsContents Current design for flexibilityCurrent design for flexibility Current accomplishmentCurrent accomplishment Immediate next stepsImmediate next steps Future concernsFuture concerns
Rules of Code DesignRules of Code Design
Fortran 90 modules, libraries built.Fortran 90 modules, libraries built. C preprocessor for compiling optionsC preprocessor for compiling options NAMELIST for running-time dimensionNAMELIST for running-time dimension Data structure for generalizationData structure for generalization Pluggable physics packagesPluggable physics packages Possibly pluggable dynamics Possibly pluggable dynamics ESMF-type for super-structureESMF-type for super-structure Easy to maintain and friendly to useEasy to maintain and friendly to use
Concept of Code StructureConcept of Code Structure
Model layers
Super structure
APIs
APIs
APIs : official ESMF; local ESMF; WRF API etc.
Element of Super StructureElement of Super Structure
package
preprocessing
execution
postprocessing
atmos
atmos_initial
atmos_model
atmos_final
initial_prep
initial_input
initial_post
model_prep
model_integrate
Model_post
final_prep
final_outputfinal_post
(read namelist, allocation)
(read input and data etc)
(constant initialized)
(allocate temporary spaces)
(deallocate temporary spaces)
(prepare data for output)
(write output or restart data)
(deallocation)
model_integrate -
integrate_init
(integrate_getgrid)integrate_dynamics
integrate_dynamicsadj(integrate_getwave)
integrate_fine ( updating, time-filter etc)
( prepare coefficients )
integrate_physics(integrate_getwave)
integrate_physicsadj
integrate_radiation
integrate_dynamicpre
integrate_physicspre(integrate_getgrid)
integrate_radiationpre(integrate_getgrid)
integrate_dynamics -
dynamics_hybrid
dynamics_nonadv
dynamics_advect
( compute all values related to vertical coordinates etc )
Implement all designsImplement all designs Implement current operational Implement current operational
dynamics and physicsdynamics and physics Testing in three different platforms: Testing in three different platforms:
ibm-sp, origin-o2k, pc-linuxibm-sp, origin-o2k, pc-linux Stable up to monthly integrationsStable up to monthly integrations Single and multiple tasksSingle and multiple tasks
Model GridModel Grid
Spectral model with spherical transform is Spectral model with spherical transform is suitable for spherical domain.suitable for spherical domain.
Reduce Gaussian grid (Williamson and Reduce Gaussian grid (Williamson and Rosinski, 2000)Rosinski, 2000)
Hybrid Parallel ComputingHybrid Parallel Computing Code structure is the same for single and multi Code structure is the same for single and multi
PE sPE s Only IO and spectral transform routine contain Only IO and spectral transform routine contain
MPI related callsMPI related calls 2D decomposition with 1D option2D decomposition with 1D option
2D can run more PE s2D can run more PE s 1D is faster in vector machine1D is faster in vector machine
Multi-threads for outmost do-loopMulti-threads for outmost do-loop Consider vector in inner do-loopConsider vector in inner do-loop For different # of PEs without recompilingFor different # of PEs without recompiling
24-h accumulated rainfall from FGM
Contour intervals of 4x10-4 m
Next StepsNext Steps
Generalized vertical coordinatesGeneralized vertical coordinates Implemented a generalized coordinatesImplemented a generalized coordinates Emphasized on sigma-theta coordinatesEmphasized on sigma-theta coordinates Current variables: U, V, T, P, and tracersCurrent variables: U, V, T, P, and tracers
Comparisons forecast skillsComparisons forecast skills Differences between sigma-p to sigma-thetaDifferences between sigma-p to sigma-theta Differences from the operational oneDifferences from the operational one
Hydrostatic system in generalized vertical coordinates
P=0
P=P
P=P
P=Ps
P=A(P+B(Ps
Isentropicddt
sigma
s
=1
infinite
=0
Future ConcernsFuture Concerns
Improve Dynamics as well as PhysicsImprove Dynamics as well as Physics Un-approximated primitive equationUn-approximated primitive equation Higher resolution physicsHigher resolution physics
Improve Numerical MethodsImprove Numerical Methods Optimal between conservation and accuracyOptimal between conservation and accuracy Adopt multi-dynamical coresAdopt multi-dynamical cores
Linkage to other components of earth Linkage to other components of earth models through ESMFmodels through ESMF
Model EquationModel Equation
Nearly all global models areNearly all global models are Hydrostatic systemHydrostatic system Diagnosis vertical momentumDiagnosis vertical momentum Shallow-atmosphere assumptionShallow-atmosphere assumption
Next generation could be years laterNext generation could be years later Very high resolution is expectedVery high resolution is expected Hydrostatic is not validHydrostatic is not valid Full Coriolis effectFull Coriolis effect Deep atmosphere Deep atmosphere
Momentum EquationMomentum Equation
€
du
dt= −
1
ρ
∂p
rcosϕ∂λ+ f sv − fcw +
uv tanϕ
r−uw
r + Fu
dv
dt= −
1
ρ
∂p
r∂ϕ − fsu −
u2 tanϕ
r−vw
r + Fv
dw
dt= −
1
ρ
∂p
∂r− g + fcu +
u2
r+v 2
r+ Fw
where f s = 2Ωsinϕ and fc = 2Ωcosϕ
Un-approximated ApproachUn-approximated Approach
From energy point of viewFrom energy point of view Energy=1/2[u(du/dt)+v(dv/dt)+w(dw/dt)]Energy=1/2[u(du/dt)+v(dv/dt)+w(dw/dt)]
Coriolis force and curvature terms are cancelled Coriolis force and curvature terms are cancelled out out
Cosine component of Coriolis force contributes Cosine component of Coriolis force contributes to zonal vertical circulationto zonal vertical circulation
And r=a+z provides accurate curvature and And r=a+z provides accurate curvature and displacementdisplacement
Generalized vertical coordinates (Staniforth and Generalized vertical coordinates (Staniforth and Wood, 2003)Wood, 2003)
Full Coriolis EffectFull Coriolis Effect
Sine component of it modifies the flow Sine component of it modifies the flow pattern at middle- and high-latitudespattern at middle- and high-latitudes
Cosine component of it modifies the Cosine component of it modifies the vertical flow patterns at tropic and extra-vertical flow patterns at tropic and extra-tropic areas.tropic areas.
Coriolis force is approached to 10Coriolis force is approached to 10-4-4 from f and 10 from u, so it is about from f and 10 from u, so it is about 1010-3-3, and w is 10, and w is 10-2-2, 10% effect in w., 10% effect in w.
Not-shallow atmosphereNot-shallow atmosphere
For shallow assumptionFor shallow assumptionr = a (earth radius)r = a (earth radius)
For non-assumptionFor non-assumptionr = a + zr = a + z
Not only affect gradients, curvature terms but also Not only affect gradients, curvature terms but also displacement by wind, displacement by wind, since u = r cossince u = r cos d d/dt and v = r d/dt and v = r d/dt/dt
For example, 50 m/s wind from100 hPa (20km) to For example, 50 m/s wind from100 hPa (20km) to 0.2 hPa (60km), errors in r=a are from 0.2 to 0.2 hPa (60km), errors in r=a are from 0.2 to above 1%, thus, errors in displacement after 10 above 1%, thus, errors in displacement after 10 days are from 20 km to 432 km.days are from 20 km to 432 km.
Final NoteFinal Note
With the combinations ofWith the combinations of(1)(1) Sigma-theta coordinates to reduce the errors Sigma-theta coordinates to reduce the errors
in vertical advection in vertical advection (2)(2) Deep atmosphere to reduce the errors in Deep atmosphere to reduce the errors in
stratospheric horizontal advectionstratospheric horizontal advection(3)(3) Full Coriolis effect to have better vertical Full Coriolis effect to have better vertical
circulation along tropical areascirculation along tropical areasThe improvement on dynamical weather and The improvement on dynamical weather and
climate forecasts can be expected.climate forecasts can be expected.