namespace mom_dynamics_split_rk2

Overview

Time step the adiabatic dynamic core of MOM using RK2 method. More…

namespace mom_dynamics_split_rk2 {

// global variables

integer id_clock_cor;

// global functions

subroutine, public step_mom_dyn_split_rk2(
    u u,
    v v,
    h h,
    tv tv,
    visc visc,
    Time_local Time_local,
    dt dt,
    forces forces,
    p_surf_begin p_surf_begin,
    p_surf_end p_surf_end,
    uh uh,
    vh vh,
    uhtr uhtr,
    vhtr vhtr,
    eta_av eta_av,
    G G,
    GV GV,
    US US,
    CS CS,
    calc_dtbt calc_dtbt,
    VarMix VarMix,
    MEKE MEKE,
    thickness_diffuse_CSp thickness_diffuse_CSp,
    Waves Waves
    );

subroutine, public register_restarts_dyn_split_rk2(
    HI HI,
    GV GV,
    param_file param_file,
    CS CS,
    restart_CS restart_CS,
    uh uh,
    vh vh
    );

subroutine, public initialize_dyn_split_rk2(
    u u,
    v v,
    h h,
    uh uh,
    vh vh,
    eta eta,
    Time Time,
    G G,
    GV GV,
    US US,
    param_file param_file,
    diag diag,
    CS CS,
    restart_CS restart_CS,
    dt dt,
    Accel_diag Accel_diag,
    Cont_diag Cont_diag,
    MIS MIS,
    VarMix VarMix,
    MEKE MEKE,
    thickness_diffuse_CSp thickness_diffuse_CSp,
    OBC OBC,
    update_OBC_CSp update_OBC_CSp,
    ALE_CSp ALE_CSp,
    setVisc_CSp setVisc_CSp,
    visc visc,
    dirs dirs,
    ntrunc ntrunc,
    calc_dtbt calc_dtbt
    );

subroutine, public end_dyn_split_rk2(CS CS);

} // namespace mom_dynamics_split_rk2

Detailed Documentation

Time step the adiabatic dynamic core of MOM using RK2 method.

This file time steps the adiabatic dynamic core by splitting between baroclinic and barotropic modes. It uses a pseudo-second order Runge-Kutta time stepping scheme for the baroclinic momentum equation and a forward-backward coupling between the baroclinic momentum and continuity equations. This split time-stepping scheme is described in detail in Hallberg (JCP, 1997). Additional issues related to exact tracer conservation and how to ensure consistency between the barotropic and layered estimates of the free surface height are described in Hallberg and Adcroft (Ocean Modelling, 2009). This was the time stepping code that is used for most GOLD applications, including GFDL’s ESM2G Earth system model, and all of the examples provided with the MOM code (although several of these solutions are routinely verified by comparison with the slower unsplit schemes).

The subroutine step_MOM_dyn_split_RK2 actually does the time stepping, while register_restarts_dyn_split_RK2 sets the fields that are found in a full restart file with this scheme, and initialize_dyn_split_RK2 initializes the cpu clocks that are used in this module. For largely historical reasons, this module does not have its own control structure, but shares the same control structure with MOM.F90 and the other MOM_dynamics_… modules.

Global Variables

integer id_clock_cor

CPU time clock IDs.

Global Functions

subroutine, public step_mom_dyn_split_rk2(
    u u,
    v v,
    h h,
    tv tv,
    visc visc,
    Time_local Time_local,
    dt dt,
    forces forces,
    p_surf_begin p_surf_begin,
    p_surf_end p_surf_end,
    uh uh,
    vh vh,
    uhtr uhtr,
    vhtr vhtr,
    eta_av eta_av,
    G G,
    GV GV,
    US US,
    CS CS,
    calc_dtbt calc_dtbt,
    VarMix VarMix,
    MEKE MEKE,
    thickness_diffuse_CSp thickness_diffuse_CSp,
    Waves Waves
    )

RK2 splitting for time stepping MOM adiabatic dynamics.

Parameters:

g	ocean grid structure
gv	ocean vertical grid structure
us	A dimensional unit scaling type
u	zonal velocity [L T-1 ~> m s-1]
v	merid velocity [L T-1 ~> m s-1]
h	layer thickness [H ~> m or kg m-2]
tv	thermodynamic type
visc	vertical visc, bottom drag, and related
time_local	model time at end of time step
dt	time step [s]
forces	A structure with the driving mechanical forces
p_surf_begin	surf pressure at start of this dynamic time step [Pa]
p_surf_end	surf pressure at end of this dynamic time step [Pa]
uh	zonal volume/mass transport
vh	merid volume/mass transport
uhtr	accumulatated zonal volume/mass transport
vhtr	accumulatated merid volume/mass transport
eta_av	free surface height or column mass time averaged over time step [H ~> m or kg m-2]
cs	module control structure
calc_dtbt	if true, recalculate barotropic time step
varmix	specify the spatially varying viscosities
meke	related to mesoscale eddy kinetic energy param
thickness_diffuse_csp	Pointer to a structure containing interface height diffusivities
waves	A pointer to a structure containing fields related to the surface wave conditions

subroutine, public register_restarts_dyn_split_rk2(
    HI HI,
    GV GV,
    param_file param_file,
    CS CS,
    restart_CS restart_CS,
    uh uh,
    vh vh
    )

This subroutine sets up any auxiliary restart variables that are specific to the unsplit time stepping scheme. All variables registered here should have the ability to be recreated if they are not present in a restart file.

Parameters:

hi	Horizontal index structure
gv	ocean vertical grid structure
param_file	parameter file
cs	module control structure
restart_cs	restart control structure
uh	zonal volume/mass transport [H L2 T-1 ~> m3 s-1 or kg s-1]
vh	merid volume/mass transport [H L2 T-1 ~> m3 s-1 or kg s-1]

subroutine, public initialize_dyn_split_rk2(
    u u,
    v v,
    h h,
    uh uh,
    vh vh,
    eta eta,
    Time Time,
    G G,
    GV GV,
    US US,
    param_file param_file,
    diag diag,
    CS CS,
    restart_CS restart_CS,
    dt dt,
    Accel_diag Accel_diag,
    Cont_diag Cont_diag,
    MIS MIS,
    VarMix VarMix,
    MEKE MEKE,
    thickness_diffuse_CSp thickness_diffuse_CSp,
    OBC OBC,
    update_OBC_CSp update_OBC_CSp,
    ALE_CSp ALE_CSp,
    setVisc_CSp setVisc_CSp,
    visc visc,
    dirs dirs,
    ntrunc ntrunc,
    calc_dtbt calc_dtbt
    )

This subroutine initializes all of the variables that are used by this dynamic core, including diagnostics and the cpu clocks.

Parameters:

g	ocean grid structure
gv	ocean vertical grid structure
us	A dimensional unit scaling type
u	zonal velocity [L T-1 ~> m s-1]
v	merid velocity [L T-1 ~> m s-1]
h	layer thickness [H ~> m or kg m-2]
uh	zonal volume/mass transport [H L2 T-1 ~> m3 s-1 or kg s-1]
vh	merid volume/mass transport [H L2 T-1 ~> m3 s-1 or kg s-1]
eta	free surface height or column mass [H ~> m or kg m-2]
time	current model time
param_file	parameter file for parsing
diag	to control diagnostics
cs	module control structure
restart_cs	restart control structure
dt	time step [s]
accel_diag	points to momentum equation terms for budget analysis
cont_diag	points to terms in continuity equation
mis	“MOM6 internal state” used to pass diagnostic pointers
varmix	points to spatially variable viscosities
meke	points to mesoscale eddy kinetic energy fields
thickness_diffuse_csp	Pointer to the control structure used for the isopycnal height diffusive transport.
obc	points to OBC related fields
update_obc_csp	points to OBC update related fields
ale_csp	points to ALE control structure
setvisc_csp	points to the set_visc control structure.
visc	vertical viscosities, bottom drag, and related
dirs	contains directory paths
ntrunc	A target for the variable that records the number of times the velocity is truncated (this should be 0).
calc_dtbt	If true, recalculate the barotropic time step

subroutine, public end_dyn_split_rk2(CS CS)

Close the dyn_split_RK2 module.

Parameters:

cs	module control structure