1. Implementation of Grid Adaptation in CAM: Comparison of Dynamic Cores Babatunde J. Abiodun 1,2 William J. Gutowski 1, and Joseph M. Prusa 1,3 1 Iowa State University, Ames, IA 2 Federal Univ.Technology, Akure, Nigeria 3 Teraflux Corp., Boca Raton, FL

2. Motivation ► Accurate Representation of regional features in global climate Static GA: for areas of interest alternative to nested grid regional models alternative to nested grid regional models advantages: advantages: consistent dynamics over high and low resolution areas small scale and large scale features fully coupled Dynamic GA: for features of interest storm tracks, hurricanes, squall lines, storm tracks, hurricanes, squall lines, frontal precipitation, Asian monsoon, frontal precipitation, Asian monsoon, tornadoes, convection tornadoes, convection EULAG (Smolarkiewicz, NCAR) is a non-hydrostatic dycore is a non-hydrostatic dycore allows static and dynamic GA allows static and dynamic GA

3. Overview ► Features of EULAG dynamic core ► CAM-EULAG ► Baseline Simulation Tests ► Summary

4. Features of EULAG: Basic Moist Equations where and j,k = 1,2,3 Jacobian weighted density (Continuity) (Momentum) (Potential Temperature) Normalized elements of Jacobi matrix Density normalized pressure perturbation Potential temp. perturbation Environmental potential temp. Allows strict adherence of numerics to fundamental conservation laws (Moisture)

5. Features of EULAG Dynamic core u Grid Adaptivity (GA) via continuous transformation of coordinate - A signature characteristic of EULAG u Nonhydrostatic, Deep Moist Anelastic Approximation - Simplifies the design of accurate and efficient numerical solvers. u Non-oscillatory Forward in Time (NFT) advection solver - Smolarkiewicz and Margolin (1998), Smolarkiewicz et al. (1999) - Multidimensional, Positive Definite Advection Transport - Multidimensional, Positive Definite Advection Transport Algorithm (MPDATA) Algorithm (MPDATA) - Positive definite solver- no spurious sign changes - Positive definite solver- no spurious sign changes - Monotonicity option prevent dispersive ripples - Monotonicity option prevent dispersive ripples - Can do nested grids with sudden changes in metric coefficients u Eulerian and semi-Lagrangian advection solver These charateristics make EULAG a good dynamic core for GA simulations in CAM

6. F Held-Suarez (1994) flow [static grid]] ( Prusa and Gutowski, 2006 ) ( Prusa and Gutowski, 2006 ) - flat terrain - flat terrain - idealized Andes - idealized Andes F Regional inertio-gravity waves [dynamic grid] (Prusa & Smolarkiewicz, 2003) (Prusa & Smolarkiewicz, 2003) F Potential flow between flapping membranes [dynamic grid] (Wedi & Smolarkiewicz, 2004) (Wedi & Smolarkiewicz, 2004) Stratified flow over a winding valley [static grid]] F Stratified flow over a winding valley [static grid]] (Smolarkiewicz & Prusa, 2004) (Smolarkiewicz & Prusa, 2004) EULAG: Previous Dynamic core Testing

7. CAM-EULAG: Coupling ► Thermodynamic Pressure and Temperature ► CAM vertical pressure velocity ► CAM Tendencies - process-split coupling - process-split coupling - EULAG requires tedencies from CAM physics - EULAG requires tedencies from CAM physics - EULAG (MPDATA) advects all prognostic fields - EULAG (MPDATA) advects all prognostic fields ► Parallel version

8. CAM-EULAG: Baseline Simulation Tests ► Aqua-planet (Neale & Hoskins, 2001) -Ensure dynamic core and physics suites are well coupled. -Compare results with current dynamic cores in CAM (FV and ESP) -Further test static and Dynamic GA ► AMIP II: Full surface-atmospheric physics -Fine tune CAM physics for EULAG dynamic core -Compare results with observation and other models ► SGMIP II: Full surface-atmospheric physics with GA - Fine tune CAM physics for high-resolution simulations - Fine tune CAM physics for high-resolution simulations - Compare results with observations and other GA models - Compare results with observations and other GA models

9. Aqua-planet: Comparison of 3 dynamic cores ► Candidates: EULAG, FV and ESP [in CAM] ► Aims: To compare similarities and differences. ► Horizontal resolutions : 2x2.5 [EULAG and FV] and T42 [ESP] ► Vertical grid point: 26 level ► Time step: 600s (EULAG), 900s (FV and ESP) ► Forcing: Idealised zonally symmetric SST ► Initialization: Eulag started from rest, FV and ESP from their standard initial conditions

10. Zonally averaged zonal wind Westerly Jet cores: EULAG (55 m/s) FV (65 m/s) ESP (60 m/s) Easterly peaks: EULAG (10 m/s) FV (10 m/s) ESP (10 m/s)

11. Zonally averaged potential Temperatue There is a good agrement between EULAG and FV ESP simulates coldest boundary layer in the tropics

12. Zonally averaged specific humidity

14. Hovemoller plot of convective precipitation,averaged over 10 o S-10 o N

16. Aqua-planet: Simulation with static GA Resolution ( o )

17. Aquaplanet: Video of simualtion with Static GA

18. Aquaplanet: Simulation with Static GA

19. ERA40 - Feb 79

20. AMIP: CAM-EULAG - Feb 79

21. NCEP - Feb 79

22. SGMIP: CAM-EULAG Grid

23. Summary ► A non-hydrostatic dynamic core that has capability for both static and dynamic grid adaptation (EULAG) is coupled with CAM. ► CAM-EULAG aqua-planet simulation agree well those from standard CAM ► AMIP and SGMIP simulations using CAM-EULAG are in progress!!!

24. Thank you!!!