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WRF-CMAQ 2-way coupled system: Part I

WRF-CMAQ 2-way coupled system: Part I. David Wong, Jonathan Pleim, Rohit Mathur, Robert Gilliam, Tanya Otte, Jeffery Young NERL/AMD Frank Binkowski and Aijun Xiu Institute for the Environment, UNC. CMAS 08 October 6-8, 2008. Outline. Current operation scheme Motivation Coupling issues

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WRF-CMAQ 2-way coupled system: Part I

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  1. WRF-CMAQ 2-way coupled system: Part I David Wong, Jonathan Pleim, Rohit Mathur, Robert Gilliam, Tanya Otte, Jeffery Young NERL/AMD Frank Binkowski and Aijun Xiu Institute for the Environment, UNC CMAS 08 October 6-8, 2008

  2. Outline • Current operation scheme • Motivation • Coupling issues • Design and features • Overall coupled structure • Preliminary results

  3. Current operation scheme

  4. 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

  5. Coupling Issues • Compatibility of met model and CMAQ • model physical aspects • computational aspects • Coupling tool

  6. Coupling Issues: compatibility • Model physical aspects • map projection • coordinate system and grid format • layer structure • time step size • etc

  7. Coupling Issues: compatibility (cont’d) • Computational aspects • domain decomposition • processor and subdomain mapping

  8. Coupling Issues: compatibility (cont’d) • Runtime System Library, RSL • RSL (MM5 and WRF), RSL-Lite (WRF) • RSL-Lite is slightly faster than RSL

  9. Coupling Issues: Tools • Earth System Modeling Framework (ESMF) • Other choices: OpenMI (UK), Model Coupling Toolkit (MCT) (ANL) • M3IO IOAPI Buffered file

  10. Design Strategy • Maintain integrity of WRF and CMAQ models • Minimal 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

  11. Features • Flexible time stepping • CMAQ can be called every WRF timestep or at any user defined multiple • Simple run time switch of feedback • Subdomain tracking • Switch back to disk I/O file for uncoupled mode

  12. WRF-CMAQ system overview WRF CMAQ emission data Solve.F vdiff biogenic emis plume rise surface flux hadv zadv hdiff cldproc chem aero physics drivers radiation microphysics initial conditions dynamics aq_prep met data boundary conditions CMAQ (time, Dt) feedback aerosol data

  13. Example of a call frequency ratio of 4 time line

  14. Preliminary results Offline – 4:1 O3 PM25

  15. Preliminary results (cont’d) 4:1 – 1:1 O3 PM25

  16. Execution time 4:45:02 2:15:23 0:04:21 2:25:18 4:52:07 9:02:52

  17. Preliminary results (cont’d) 4:1 w/o – w/ feedback O3 PM25

  18. Preliminary results (cont’d) w/ feedback 4:1 – 1:1 O3 PM25

  19. Preliminary results (cont’d) w/ feedback 4x8 – 2x4 O3 PM25

  20. Exec. time case w/o feedback w/ feedback 1:1 16:36:04 2x4 8:18:00 4:1 1:1 9:26:11 9:34:28 4x4 4:1 5:13:50 5:20:56 1:1 5:55:10 4x8 3:34:47 4:1 Execution time (cont’d)

  21. To be continued …

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