1. Linkage between WRF/NMM and CMAQ Daewon Byun (PI) C.K. Song & P. Percell University of Houston Institute for Multidimensional Air Quality Studies (IMAQS) Coauthors: Jon Pleim, Tanya Otte, Jeff Young, Rohit Mathur ASMD, Air Resources Laboratory, NOAA In partnership with U.S. EPA and many others… Hsin-Mu Lin, David Wong, etc…

2. Consistent governing set of equations & state variables Consistent coordinates and grid structures Consistent numerics & physics, and parameterizations Flexible: able to help diverse stake holders (research – regulatory application – use of different emissions inputs) Allow studying effects of using different basic input data (e.g., Land Use/Land Cover, topography, emissions, etc) separately Same (*) numerics & physics, and parameterizations Same (*) coordinates and grid structures Same (*) governing set of equations & state variables What are the main science issues of the NWP & AQM coupling? Off-line On- line * Need to check how closely the dynamics variables and trace species are matched

3. WRF/nmm WRF/nmm Postprocessors (vertical/horizontal) PREMAQ* (consistent vertical coordinate) CMAQ Loose couplingTight coupling WRF/nmm WRF-CMAQ Interface Processor CMAQ/E-grid Components of Off-line Coupled system Spatial interpolation Lambert conformal projection C-grid On rotated lat/long E-grid coordinate Consistent vertical coordinate

4. Fully Compressible Atmosphere (OOyama, 1990) used for CMAQ Follow coordinates/grid of met model Reproduce Jacobian Couple state variables consistently Proper Coupling Requires

5. WRF/NMM http://www.dtcenter.org/wrf-nmm/users / Nonhydrostatic Mesoscale Model (NMM) core of the Weather Research and Forecasting (WRF) system was developed by NOAA/NCEP ARW (Advance Research WRF) + Terrain following hydrostatic P coord. or Terrain following sigma (ARW) + Arakawa-C + Conserves mass, momentum, dry entropy, and scalar WRF/NMM + Hybrid sigma-pressure coord. + Arakawa-E + Conserves mass, momentum, enstrophy, TKE and scalar WRF (ARW core)WRF (NMM core)

6. Hybrid Sigma-Pressure Coordinate

7. Initial Terrain-Following Hydrostatic Sigma coordinate Method 1 Method 2 : sigma interface of the lower and upper layers PD: pressure of top of lower layer Define J for the Generalized Vertical Coordinate

8. Vertical Jacobian Discontinuity Problem & Solution For example, SIGMA LEVELS = 1.0000,.9976,.9948,.9920,.9890,.9858,.9825,.9790,.9754,.9718,.9679,.9637,.9590,.9538,.9480,.9415,.9340,.9251,.9144,.9020,.8883,.8736,.8582,.8420,.8253,.8079,.7900,.7714,.7523,.7326,.7124,.6915,.6699,.6477,.6248,.6015,.5779,.5540,.5300,.5057,.4812,.4566,.4319,.4070,.3822,.3576,.3333,.3100,.2881,.2679,.2494,.2316,.2135,.1936,.1707,.1445,.1159,.0863,.0569,.0282,.0000, Case 1) Surface pressure = 101300 Pa & sigma(kc)=0.3822, P kc PDPD top Js(lower)Js(upper) JP method 418065949436806 118988/ρg73612/ρg UH method96300/ρg Case 2) Surface pressure = 70000 Pa & sigma(kc)=0.3822, P kc PDPD top Js(lower)Js(upper) JP method 418062819436806 56388/ρg73612/ρg UH Method45636/ρg96300/ρg One way to remove discontinuity

9. Horizontal E-Grid System of WRF/nmm: Rotated lat./long & Arakawa-E grid -> C-grid for CMAQ If we use diamond grid C(C,R,L,S) -> C*(CR, L,S)

10. Dynamics with Semi-Staggered Arakawa E grid The E grid is essentially a superposition of two C grids. When only the adjustment terms in the equations of motion and continuity are considered, two large-scale solutions from each C grid may exist independently, and a noisy total solution results. So, employ the forward-backward time differencing scheme to prevents gravity wave separation and thereby precludes the need for explicit filtering (Mesinger 1973: Mesingerand Arakawa 1976; Janji´c 1979). (1,1)(2,1) (1,2)(2,2) (223,501) (223,500) (222,501) (222,500) dx dy dx dx = 0.0534521 deg. (rotated Lon.) dy = 0.0526316 deg. (rotated Lat.) 2dx scalar vector Advantages of using E-grid with dynamics solution

11. Dimension for Grid Point Dot-PointCross-PointFlux-Point For MM5 (MCIP) (NCOL+1, NROW+1)(NCOL, NROW) X-dir (NCOL+1, NROW) Y-dir (NCOL, NROW+1) For WRF/ARW (WCIP) (NCOL+1, NROW+1)(NCOL, NROW) X-dir (NCOL+1, NROW) Y-dir (NCOL, NROW+1) For WRF/NMM (NCOL, NROW) Consistent coordinates and grid structures WRF/EM & CMAQ utilize Arakawa-C Grid Arakawa-B Grid (MM5) is linearly interpolated onto Arakawa-C Grid (CMAQ) What to do with NMM E-grid data?

12. How to Utilize Arakawa-E for CMAQ? Develop a horizontal advection algorithm in CMAQ for Arakawa E-grids Split 2-D horizontal advection operator into 1-D operators and use CMAQ- proven 1-D schemes, such as PPM, with alternation between appropriate X and Y directions Work directly with meteorological variables on the E-grid - avoid spatial interpolation Use rotated square cells (rotated B-grid then on C-grid) Spatial distribution of dependent variables for a uniformly spaced Arakawa E-Grid E-Grid with rotated square cells. Scalar variables are considered to be constant on each grid

13. Advantages Makes the E-Grid look like a B-grid whose “rows” and “columns” are along diagonal SW → NE and SE → NW lines Can use 1-D algorithm, e.g. PPM, along these lines CMAQ (and preprocessors) are familiar with turning B-grid data into C-grid flux point data Disadvantages Diagonal lines of cells have variable lengths, which requires non- trivial extra book-keeping (in EGRID_MODULE.F) Requires interpolation of wind velocities to get flux point values Jagged boundary effect Parallelization could be more difficult

14. Grid geometry changes depending on whether the number of columns or rows is even or odd Bookkeeping issues Partitioning for parallelization

15. Jagged Boundary Effect Boundary values propagate into the domain because boundaries are angled 45 degree rotated B-grid then on C-grid

16. Option 1: rotated B-grid then on C-grid CMAQ C-grid Comparison between regular CMAQ and Option 1

17. START get env./IOAPI variables define grid/coord. - rotated Lat./Lon coord. - E-grid structure - calculate Dx & Dy - allocate memory xgrid and cgrid get met. data calculation for WRF/NMM - Eta1 & Eta2 - geopotential height - hydrostatic pressure - hydrometeor derive dynamic fld. GRIDOUT METCRO/DOTOUT continue END Calculation Flow of WCIP/NMMMapping Variables

18. TEST Run - Target Period : 00Z June 28 - 06Z June 30, 2006 - Horizontal Resolution : ~ 12 km

19. Model Configuration C-GridE-Grid ----------------------------------------------------------------------------------------- Met.MM5 v3.6.1WRF/NMM v2.1 (w/ Eta forecast) MCIPMCIP v3.0WCIP/NMM v1.0 BCONBCON/StandardBCON/E-grid v1.0 ICONICON/ StandardICON/ E-grid v1.0 CMAQCMAQ v4.4CMAQ/ E-grid v1.0 ----------------------------------------------------------------------------------------- + I.C.C-Grid UH-AQF/CMAQ 12km resolution output 00Z June 28, 2006 + B.C.C-Grid UH -AQF /CMAQ 36km resolution output 00Z June 28 – 06Z June 30, 2006 + Emisson None + Chem. Mech.CB-IV

20. Domain Configuration C-GridE-Grid ----------------------------------------------------------------------------------------- Met.(MM5)(WRF/NMM) + nx(dx)100(12 km)85(0.0780 deg.*) + ny(dy)100(12 km)135(0.0724 deg.) + nz43 sigma 44 hybrid sigma-P CMAQ + nx(dx)89**57*** + ny(dx)89113 + nz23 (see COORD_23L.EXT)23 (JP & Dis.) ----------------------------------------------------------------------------------------- * ds=sqrt(dx**2+dy**2) ~ 12 km ** As for DOT case of MCIP, nx and ny should be 90 ** As for CRO/DOT case of WCIP/NMM, nx(ny) should be 59(115)

21. Recommended Model Physics for WRF/NMM Microphysics: Ferrier Cumulus Convection: Betts-Miller-Janjic Shortwave Radiation: GFDL Longwave Radiation: GFDL Lateral diffusion: Smagorinsky PBL, free atmosphere: Mellor-Yamada-Janjic Surface Layer: Janjic Scheme Land-Surface: 4-layer soil model

23. CMAQ Results No emissions, Transport & Chemistry Only 12Z (06 CST) June 28, 2006 (12 hrs after initial time)

24. C-Grid E-Grid Wind PBLH CO O3

25. hr18

26. C-Grid E-Grid ZH Jabobian Air temp. U-wind ---- 13000 m discontinuity

27. C-Grid E-Grid CO

28. C-Grid E-Grid O3

29. Conclusion + Presented a method to cast the WRF meteorological data on CMAQ grid & coordinate structures to represent transportation of pollutants. + Developed WCIP/NMM, BCON/E-grid, ICON/E-grid, and CMAQ/E-grid + Performed simulation (WRF/NMM -> CMAQ/E-grid) was successfully done + A simple evaluation with transport and chemistry was performed Results of CMAQ/E-grid simulation is generally consist with CMAQ/C-grid but reveal properly the discrepancy of meteorological fields Future Work + To solve some unsolved problems (WRF/NMM IOAPI, etc) + More Evaluations & Documentation + Deliver the developed codes to NOAA/EPA for National AQF