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 IntroductionObjectives Model Formulations Features Code Flow Chart Test Cases References

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:

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

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:

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

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)

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

Code Flow Chart Preprocessor Metgen - Kbview - Yzgrid -Z coordinates data - Topography parameters Indata - Zkb - Initial - Boundaries - Depth - Invu -Annualevitus - Winds - Fixedlev - 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 Prep - Rundata - Kbview_prep - EVP -Windmix -Ibmarray - Vertical diffusion coefficients - Z level info - EVP pressure solver coefficient - VBK, VHK data - Immersed boundary data

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

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

Code Flow Chart Multi-Domain diagram Main processing - Multi-Domain diagram ZONE A ZONE B ZONE C MASTER SLAVE DOMAIN TYPE for TIMCOM SZONE2DZONE DZONESZONEDZONESZONEDZONESZONEDZONESZONE DZONE2SZONE

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

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

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

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).Dietrich et al., 1996

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.

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).

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°.

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.

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.

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

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