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Overview of the TaIwan Multi-scale Community Ocean Model (TIMCOM)

Overview of the TaIwan Multi-scale Community Ocean Model (TIMCOM). Wee-Beng Tay 1 , Yu-heng Tseng 1 , Nelson Chien 2 , Yu-chiao Liang 1 , Mu-hua Chien 1. 1 Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan, 2 National Taiwan University, Taipei, Taiwan,. Outlines.

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Overview of the TaIwan Multi-scale Community Ocean Model (TIMCOM)

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  1. Overview of the TaIwan Multi-scale Community Ocean Model (TIMCOM) Wee-Beng Tay1, Yu-heng Tseng1, Nelson Chien2, Yu-chiao Liang1, Mu-hua Chien1 1Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan, 2National Taiwan University, Taipei, Taiwan,

  2. Outlines • Introduction • Objectives • Model Formulations • Features • Code Flow Chart • Test Cases • References

  3. Introduction • TIMCOM - TaIwan Multi-scale Community Ocean Model • Flexible community ocean model for simulating a variety of idealized and real ocean flows over a wide range of scales and boundary conditions. • Written in Fortran 90 with a flexible user interface, allowing customization with ease. • Evolved from DieCAST (Dietrich Center for Air Sea Technology) ocean model (Dietrich et al., 1997). Complete family tree of TIMCOM is shown below:

  4. Objectives • Provide a flexible, simple and user friendly community ocean modeling system for simulating a wide variety of real and idealized ocean flows over a wide range of scales and boundary conditions. • Multiple-grid capability resolves the key and fine features if needed (Dietrich et al., 2008). • Model suitable for resolving the multi-scale ocean dynamics. • Public version released by June 30 on the internet at http://efdl.as.ntu.edu.tw/research/timcom.

  5. Model Formulations • Governing equations of the hydrostatic TIMCOM model based on the 3D primitive equations for an incompressible, stratified fluid. (Quasi non-hydrostatic version also available.) • Conservation of potential temperature and salinity: • Horizontal momentum equations:

  6. Model Formulations • Conservation of mass, Hydrostatic equation and Equation of state: • The convection, horizontal diffusion operators L,Dm(h) are defined as:

  7. Features • Supporting hydrostatic/quasi non-hydrostatic approximation • Fully fourth-order-accurate approximations in the solution procedure and a new EVP parallel solver • Lagrangian tracers releases capacity • Grid coupling, multiple gridded one- and two-way grid coupling are supported (Dietrich et al., 2004; Dietrich et al., 2008) • Several turbulence parameterization options (PP, KPP and PWP)

  8. Features • Different time-advanced schemes options (Filtered, unfiltered Leap-frog, modified Leap-frog (Williams, 2009), Adam-Bashforth and Runge-Kutta third-order) • Immersed boundary methods for topology (mid. 2010) • NetCDF output to allow machine independent access and sharing of data. • NCL graphics output for portability and robustness • Ensemble simulation capability

  9. Code Flow Chart Prep • Rundata • Kbview_prep • EVP • Windmix • Ibmarray Metgen • Kbview • Yzgrid Indata • Zkb • Initial • Boundaries • Depth • Invu • Annualevitus • Winds • Fixedlev • Preprocessor Vertical diffusion coefficients Z level info EVP pressure solver coefficient VBK, VHK data Immersed boundary data - Depth, land/water classification • Old temperature, salinity data • Sponge layer climatology • Depth info • Model and input level • Old temperature, salinity data • Levitus climatology/ Hellerman winds • Modelfied Levitus climatology Z coordinates data Topography parameters

  10. Code Flow Chart • There are 7 kinds of template source code type • P - General procedure for main and input • O - General modules and useful solvers , tools • M - TIMCOM principal template source code • I - Include file for M type code • S - Ocean dynamic simulation template source code • T - Multi-zone coupling template source code • G - Non-directory, file generated by configurator • Main processing - Source Code Structure

  11. Code Flow Chart • Target code generator, generate case source code from template source code. • Configure file：read in by configurator, defines domain name by typing DOMAIN <DOMAIN> key word. • Supports one domain and multi domain • Usage：./configure <configure file> • Example：./configure configure.txt • An example for configure.txt • DOMAIN NPB • DOMAIN TAI • Main processing - Configurator

  12. Code Flow Chart SZONE SZONE DZONE DZONE SZONE SZONE DZONE DZONE • Main processing - Multi-Domain diagram ZONE A SZONE2DZONE ZONE B ZONE C DZONE2SZONE DOMAIN TYPE for TIMCOM SLAVE MASTER SLAVE

  13. Code Flow Chart • MAIN ( P type：main.f90 ) • TIMCOM_GETARGS • TIMCOM_OPENLOG • INIT • TIME EVOLUATION LOOP • TIMCOM ( G type ) • STOPSIG CHECK • STOPSIG READ • END OF TIME EVOLUATION LOOP • TIMCOM_CLOSELOG • TIMCOM_STOPSIG_SIGNAL • Main processing - Main Procedure Time Evolution Loop

  14. Code Flow Chart • Controlling running step • File：stoprun • Location：working directory • Value： • 0：finish the job without any condition • 1：checkpoint job and stop it • 2 or above：re-assign maximum evolution timestep • Coding in O type template source code：general.f90 • Running Controller - STOPSIG

  15. Code Flow Chart • Restarting a run • ensure all restart file has been preparedrestart directory：<work directory>/TEMP_<DOMAIN>/ • restart case with “./timcom 1” • Running Controller - Restart • Return Signal • Job return signal when job leave user space • 0：job successful complete • 1：job has been checkpoint and stop • 2：job failure • Coding in O type template source code：general.f90

  16. Test Cases • Two dimensional flow over an island • Two dimensional, hydrostatic TIMCOM ocean model, simulating the idealized oceanic flow around small islands patterned after Barbados, W. I. (Dietrich et al., 1996). The velocity fields are illustrated in the figure below at day 5 and 111 at (80x80).

  17. Test Cases • Investigating the generation processes of internal solitary waves (ISWs) in LS using a 2-D numerical model with idealized topography (Tao et al., 2008). • A strong tide is imposed, giving a steeper initial depression and a group of ISWS being generated.

  18. Test Cases • The idealized bottom density current problem for The Dynamics of Overflow Mixing and Entrainment (DOME) (Tseng and Dietrich (2006), patterned after the Denmark Strait). • Snapshots of bottom boundary tracer concentration (c) on 4 different model days from the 2.5-km resolution run (R3L).

  19. Test Cases • Dual-grid North Pacific Ocean (DUPOM) to simulate the regional circulation in Asian Marginal Seas. • Left figure shows the coupled model domains while the right shows the western Pacific domain with a higher horizontal resolution of 1/8°×1/8°.

  20. Test Cases • Dual-grid North Pacific Ocean (DUPOM) to simulate the regional circulation in Asian Marginal Seas. • The cycle of the Kuroshio path in the region south of Japan between LM and NLM paths repeats with a period of more than a year in this model. Strong broclinic dynamics are observed from the transition.

  21. Test Cases • The global 2°x2° resolution ocean model with 31 vertical levels. • Higher resolution is used for climate study. Sample instantaneous temperature contour and surface velocity vector are shown below.

  22. Test Cases • The global 2°x2° resolution ocean model with 31 vertical levels. • Tracer capability of TIMCOM is also demonstrated below.

  23. Thank you very much!

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