Development and Evaluation of a High Resolution Oceanic General Circulation Model (OGCM)

1. Development and Evaluation of a High Resolution Oceanic General Circulation Model (OGCM) Yongqiang YU, Hailong Liu, Pengfei Lin, Xuehong Zhang, Huier Mo LASG/IAP/CAS Guilin, China, October 28th-31st , 2013

2. Outline • Introduction • Model Description • Numerical and Parallel Computing Schemes • Large-scale Circulation • Marginal Sea Circulation near China • Summary

3. 10.6% /10 years

4. Global Mean Surface Air Temperature Change (IPCC, 2013)

5. How to reduce the Model Uncertainties • Increase spatial resolution of climate system models • Improve Numerical Methods • Improve the subgrid physical parameterization schemes • Introduce new component models

6. Spectrum of Kinetic Energy in the ocean

7. Outline • Introduction • Model Description • Numerical and Parallel Computing Schemes • Large-scale Circulation • Marginal Sea Circulation near China • Summary

8. Ocean Model Development History at LASG/IAP • 4-Level (4X5) OGCM by Zhang et al. (1989) Convex-C120 • 20-Level (4X5) OGCM by Chen et al. (1997) Convex-C3210 • 30-Level (2X2) GCM by Jin et al. (1999) SGI workstation • LICOM1.0 (0.5X0.5) by Liu et al. (2003) SGI and IBM • LICOM2.0 (0.1X0.1) by Liu et al. (2012) and Yu et al. (2012) • (TH-1A)

9. Approximations and Equations

10. Barotropical Equations

11. Sub-Grid Physical Parameterizations • Turbulent Mixing schemes (Canuto, 2003,2007) • Solar radiation penetration scheme • Bottom drag scheme • Bi-Harmonic diffusion/viscosity

12. Outline • Introduction • Model Description • Numerical and Parallel Computing Schemes • Large-scale Circulation • Marginal Sea Circulation near China • Summary

13. Z-Coordinate and Latitude-Longitude grid • Leap-frog time integration • Barotropic and Baroclinic Split Technology • 2-order central difference for momentum advection • Two-step shape-preserving scheme for temperature and salinity advection • Implicit scheme for vertical diffusion/viscosity • 2-D MPI Parallel Computing

14. Speed-up in TianHe-1A • Zonal filter in high latitudes lead to imbalance • Serial IO becomes key bottleneck

15. Experiment Design of LICOM2.0 • 12-year spin-up forced NCEP climatological flux • 2000-2007 simulation by daily forcing form NCEP Heat Flux and QuickSCAT wind stress • A 60-year integration with NCEP reanalysis. • 1 model year/ 2 days

16. Outline • Introduction • Model Description • Numerical and Parallel Computing Schemes • Large-scale Circulation • Marginal Sea Circulation near China • Summary

17. Standard Deviation of Sea Level Height

18. SST Snapshot near Western Boundary

19. Observed and Simulated zonal cuurent in the tropic Pacific

20. Kuroshio Path from 2000 to 2007

21. 5-daily mean integrated transports MOC=FC+EK+MO FC：Florida Current transport ，r=0.43 RAPID (dash line) model (solid line) MOC， r=0.62 EK：Ekman transport r=0.96 MO：upper mid-ocean transport ， r=0.3

22. Power Spectrum of 5-daily mean transports CMIP3models (from Sarojini et al. 2011) the black line is OBS hardly reproduce the 30 to 40 days period LICOM successfully represent this feature LICOM

23. Velocity profile of ITF (m/s) . Lombok Makassar Ombai Lifatomola Timor

24. Annual mean volume transport

25. Time series of Volume transport

26. Outline • Introduction • Model Description • Numerical and Parallel Computing Schemes • Large-scale Circulation • Marginal Sea Circulation near China • Summary

27. Depth-Longitude section of observed and simulated temperature along 35N

28. Jan Apr Jul Oct

29. Luzon transport in upper(0-500), middle (500-1500) and deep layers (<1500).

30. Summary • Compared with coarse resolution of the ocean model LICOM, the eddy-resolving version well reproduces the meso-scale eddies as observed. • The model doesn’t only reproduce equatorial current system such as EUC, ETC etc, but also oceanic circulation in the North Pacific. • The model can simulate the large meander of Kuroshio, as well as its interannaul variability. • The marginal sea circulation near China are also reproduced by the eddy-resolving model. • The mass transport along 26.5N and Indonesian straits are well reproduced.

31. Ongoing Work • Sub-grid Parameterizations: Tidal mixing, wave mixing, internal wave mixing etc. • Dynamical Core: Time integration scheme • Tripole Coordinate: reduce load imbalance • Parallel Optimization : MPI + Open MP • High resolution coupled Ocean-Atmosphere Model

32. Next Step • 在LICOM模式中引进三极坐标 • 改进湍流混合方案 • 引进潮汐混合、波浪混合、底边界层混合方案等 • 进行高分辨率耦合试验.

33. Time mean temperature transects at 26.5ºN LICOM can reproduce the observational temperature structure WOA09 LICOM LICOM-WOA09 LICOM can’t resolve the Bahamas at the western boundary, and the depth of Florida Straits is too shallow compared to the real topography.

34. Schematic of MOC monitoring array at 26ºN from Rayner et al.，2011 QuickScat

35. meridional heat transport R=0.68 Underestimated by 0.2PW

36. Mass and Heat Transport along 26.5N in North Atlantic Purpose: evaluate the ability of the eddy-resolving ocean circulation model LICOM to reproduce the variabilities of AMOC on the time mean scale and the time scales less than one year against the high frequency observational data (RAPID data) along 26.5 ºN in Atlantic.

37. Volume Transport across Luzon Strait（Unit：Sv)

38. OBS (2007) OBS (2005) Model (2007) Model (2005) Observed and Simulated SSH Anomaly in 2005 and 2007

39. Zonal Current along 160E Mar Dec Jun Sep

40. LICOM SODA Deep layer transport across Luzon strait

41. Zonal Jets in the subtropics