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Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
WRF-CMAQ 2-way coupled system: Part IDavid Wong, Jonathan Pleim, Rohit Mathur, Robert Gilliam, Tanya Otte, Jeffery YoungNERL/AMD
Frank Binkowski and Aijun XiuInstitute for the Environment, UNC
CMAS 08October 6-8, 2008
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Outline
Current operation schemeMotivationCoupling issuesDesign and featuresOverall coupled structurePreliminary results
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Current operation scheme
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Motivation
Shortcomings of the current way of running met model- MCIP-CMAQ• 32-bit data storage in files• excessive data interpolation• lack of feedback (direct and indirect
effect) from CMAQ to the met model
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Coupling Issues
Compatibility of met model and CMAQ• model physical aspects• computational aspects
Coupling tool
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Coupling Issues: compatibility
Model physical aspects• map projection• coordinate system and grid format• layer structure• time step size• etc
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Coupling Issues: compatibility (cont’d)
Computational aspects• domain decomposition• processor and subdomain mapping
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Coupling Issues: compatibility (cont’d)
Runtime System Library, RSLRSL (MM5 and WRF), RSL-Lite (WRF)RSL-Lite is slightly faster than RSL
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Coupling Issues: Tools
Earth System Modeling Framework (ESMF)
Other choices: OpenMI (UK), Model Coupling Toolkit (MCT) (ANL)
M3IO IOAPI Buffered file
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Design Strategy
Maintain integrity of WRF and CMAQ modelsMinimal code changes:
• Keeping the same IOAPI calls• Easy to incorporate new version of WRF
Efficiency: Low coupling overhead• buffered file for data transfer (forward and backward)• buffered file always holds two time steps of data
allowing interpolation Flexibility: easy to add feedback parameters and outputs
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Features
Flexible time stepping • CMAQ can be called every WRF
timestep or at any user defined multiple Simple run time switch of feedbackSubdomain trackingSwitch back to disk I/O file for uncoupled mode
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
WRF-CMAQ system overview
WRF CMAQSolve.F
physics drivers
dynamics
aq_prep
CMAQ (time, t)
aerosol data
radiationmicrophysics
emissiondatavdiff
biogenic emisplume rise
surface fluxhadvzadvhdiffcldprocchemaero
feedback
initialconditions
boundaryconditions
met data
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Example of a call frequency ratio of 4
time line
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Preliminary results
Offline – 4:1O3 PM25
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Preliminary results (cont’d)
4:1 – 1:1O3 PM25
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Run Exec. Time
Met Only
MCIP
Offline CMAQ
Inline Model 4:1
Inline Model 1:1
Execution time
4:45:022:15:23
0:04:21
2:25:18
4:52:07
9:02:52
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Preliminary results (cont’d)
4:1 w/o – w/ feedback
O3 PM25
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Preliminary results (cont’d)w/ feedback 4:1 – 1:1
O3 PM25
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Preliminary results (cont’d)
w/ feedback 4x8 – 2x4O3 PM25
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
Execution time (cont’d)
Exec. time
w/o feedback w/ feedbackcase
2x4 1:1
1:1
1:1
4:1
4:1
4:1
4x4
4x8
16:36:04
8:18:00
9:34:28
5:20:56
5:55:10
3:34:47
9:26:11
5:13:50
Office of Research and DevelopmentAtmospheric Modeling Division, National Exposure Research Laboratory
To be continued …