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d67096e55c Jeff*0001 .. _sec_global_oce_latlon:
0002
0003 Global Ocean Simulation
0004 =======================
0005
0006 (in directory: :filelink:`verification/tutorial_global_oce_latlon/`)
0007
0008 This example experiment demonstrates using the MITgcm to simulate the
0009 planetary ocean circulation. The simulation is configured with
0010 realistic geography and bathymetry on a
0011 :math:`4^{\circ} \times 4^{\circ}` spherical polar grid. Fifteen levels are used in the
0012 vertical, ranging in thickness from 50 m at the surface to 690 m at depth, giving a
0013 maximum model depth of 5200 m. Different time-steps are
0014 used to accelerate the convergence to equilibrium (see Bryan 1984 :cite:`bryan:84`)
0015 so that, at this resolution, the
0016 configuration can be integrated forward for thousands of years on a
0017 single processor desktop computer.
0018
0019 Overview
0020 --------
0021
0022 The model is forced with climatological wind stress data from Trenberth (1990)
0023 :cite:`trenberth:90` and NCEP surface flux data from Kalnay et al. (1996)
0024 :cite:`kalnay:96`. Climatological data (Levitus and Boyer 1994a,b :cite:`levitus:94a,levitus:94b`)
0025 is used to initialize the model
0026 hydrography. Levitus and Boyer seasonal climatology
0027 data is also used throughout the calculation to provide additional
0028 air-sea fluxes. These fluxes are combined with the NCEP climatological
0029 estimates of surface heat flux, resulting in a mixed boundary condition
0030 of the style described in Haney (1971) :cite:`haney:71`. Altogether, this
0031 yields the following forcing applied in the model surface layer.
0032
0033 .. math::
0034 {\cal F}_{u} = \frac{\tau_{x}}{\rho_{0} \Delta z_{s}}
0035 :label: eg-global_forcing-Fu
0036
0037 .. math::
0038 {\cal F}_{v} = \frac{\tau_{y}}{\rho_{0} \Delta z_{s}}
0039 :label: eg-global_forcing-Fv
0040
0041 .. math::
0042 {\cal F}_{\theta} = - \lambda_{\theta} ( \theta - \theta^{\ast} )
0043 - \frac{1}{C_{p} \rho_{0} \Delta z_{s}}{\cal Q}
0044 :label: eg-global_forcing-Ftheta
0045
0046 .. math::
0047 {\cal F}_{s} = - \lambda_{s} ( S - S^{\ast} )
0048 + \frac{S_{0}}{\Delta z_{s}}({\cal E} - {\cal P} - {\cal R})
0049 :label: eg-global_forcing-Fs
0050
0051 where :math:`{\cal F}_{u}`, :math:`{\cal F}_{v}`,
0052 :math:`{\cal F}_{\theta}`, :math:`{\cal F}_{s}` are the forcing terms in
0053 the zonal and meridional momentum and in the potential temperature and
0054 salinity equations respectively. The term :math:`\Delta z_{s}`
0055 represents the top ocean layer thickness in meters. It is used in
0056 conjunction with a reference density, :math:`\rho_{0}` (here set to
0057 999.8 kg m\ :sup:`-3`), a reference salinity, :math:`S_{0}`
0058 (here set to 35 ppt), and a specific heat capacity, :math:`C_{p}` (here
0059 set to 4000 J kg\ :sup:`-1` K\ :sup:`-1`), to
0060 convert input dataset values into time tendencies of potential
0061 temperature (with units of :sup:`o`\ C s\ :sup:`-1`),
0062 salinity (with units ppt s\ :sup:`-1`) and velocity (with units
0063 m s\ :sup:`-2`). The externally supplied forcing fields
0064 used in this experiment are :math:`\tau_{x}`, :math:`\tau_{y}`,
0065 :math:`\theta^{\ast}`, :math:`S^{\ast}`, :math:`\cal{Q}` and
0066 :math:`\mathcal{E}-\mathcal{P}-\mathcal{R}`. The wind stress fields (:math:`\tau_x`,
0067 :math:`\tau_y`) have units of N m\ :sup:`-2`. The
0068 temperature forcing fields (:math:`\theta^{\ast}` and :math:`Q`) have
0069 units of :sup:`o`\ C and W m\ :sup:`-2`
0070 respectively. The salinity forcing fields (:math:`S^{\ast}` and
0071 :math:`\cal{E}-\cal{P}-\cal{R}`) have units of ppt and
0072 m s\ :sup:`-1` respectively. The source files and
0073 procedures for ingesting this data into the simulation are described in
0074 the experiment configuration discussion in section
0075 :numref:`sec_eg-global-clim_ocn_examp_exp_config`.
0076
0077 Discrete Numerical Configuration
0078 --------------------------------
0079
0080 The model is configured in hydrostatic form. The domain is discretized
0081 with a uniform grid spacing in latitude and longitude on the sphere
0082 :math:`\Delta \phi=\Delta \lambda=4^{\circ}`, so that there are 90
0083 grid cells in the zonal and 40 in the meridional direction. The
0084 internal model coordinate variables :math:`x` and :math:`y` are
0085 initialized according to
0086
0087 .. math::
0088
0089 x &= r\cos(\phi), &\Delta x & = r\cos(\Delta \phi)
0090
0091 y &= r\lambda, &\Delta y &= r\Delta \lambda
0092
0093 Arctic polar regions are not included in this experiment. Meridionally
0094 the model extends from 80\ :sup:`o`\ S to
0095 80\ :sup:`o`\ N. Vertically the model is configured with
0096 fifteen layers with the following thicknesses:
0097
0098 | :math:`\Delta z_{1}` = 50 m
0099 | :math:`\Delta z_{2}` = 70 m
0100 | :math:`\Delta z_{3}` = 100 m
0101 | :math:`\Delta z_{4}` = 140 m
0102 | :math:`\Delta z_{5}` = 190 m
0103 | :math:`\Delta z_{6}` = 240 m
0104 | :math:`\Delta z_{7}` = 290 m
0105 | :math:`\Delta z_{8}` = 340 m
0106 | :math:`\Delta z_{9}` = 390 m
0107 | :math:`\Delta z_{10}` = 440 m
0108 | :math:`\Delta z_{11}` = 490 m
0109 | :math:`\Delta z_{12}` = 540 m
0110 | :math:`\Delta z_{13}` = 590 m
0111 | :math:`\Delta z_{14}` = 640 m
0112 | :math:`\Delta z_{15}` = 690 m
0113
0114 (here the numeric subscript indicates the model level index number,
0115 :math:`{\tt k}`) to give a total depth, :math:`H`, of
0116 -5200 m. The implicit free surface form of the pressure
0117 equation described in Marshall et al. (1997) :cite:`marshall:97a` is employed. A
0118 Laplacian operator, :math:`\nabla^2`, provides viscous dissipation.
0119 Thermal and haline diffusion is also represented by a Laplacian
0120 operator.
0121
0122 Wind-stress forcing is added to the momentum equations in
0123 :eq:`eg-global-model_equations_uv` for both the zonal
0124 flow :math:`u` and the meridional flow :math:`v`, according to
0125 equations :eq:`eg-global_forcing-Fu` and :eq:`eg-global_forcing-Fv`. Thermodynamic
0126 forcing inputs are added to the equations in
0127 :eq:`eg-global-model_equations_ts` for potential
0128 temperature, :math:`\theta`, and salinity, :math:`S`, according to equations
0129 :eq:`eg-global_forcing-Ftheta` and :eq:`eg-global_forcing-Fs`. This produces a set
0130 of equations solved in this configuration as follows:
0131
0132 .. math::
0133 :label: eg-global-model_equations_uv
0134
0135 \frac{Du}{Dt} - fv +
0136 \frac{1}{\rho}\frac{\partial p'}{\partial x} -
0bad585a21 Navi*0137 \nabla _h \cdot (A_{h} \nabla _h u) -
0138 \frac{\partial}{\partial z}\left(A_{z}\frac{\partial u}{\partial z}\right)
d67096e55c Jeff*0139 &=
0140 \begin{cases}
0141 \mathcal{F}_u & \text{(surface)} \\
0142 0 & \text{(interior)}
0143 \end{cases}
0144 \\
0145 \frac{Dv}{Dt} + fu +
0146 \frac{1}{\rho}\frac{\partial p'}{\partial y} -
0bad585a21 Navi*0147 \nabla _h \cdot (A_{h} \nabla _h v) -
0148 \frac{\partial}{\partial z}\left(A_{z}\frac{\partial v}{\partial z}\right)
d67096e55c Jeff*0149 &=
0150 \begin{cases}
0151 \mathcal{F}_v & \text{(surface)} \\
0152 0 & \text{(interior)}
0153 \end{cases}
0154
0155 .. math::
0bad585a21 Navi*0156 \frac{\partial \eta}{\partial t} + \nabla _h \cdot \vec{\bf u} = 0
d67096e55c Jeff*0157
0158 .. math::
0159 :label: eg-global-model_equations_ts
0160
0161 \frac{D\theta}{Dt} -
0bad585a21 Navi*0162 \nabla _h \cdot (K_{h} \nabla _h \theta)
0163 - \frac{\partial}{\partial z}\left(\Gamma(K_{z})\frac{\partial\theta}{\partial z}\right)
d67096e55c Jeff*0164 &=
0165 \begin{cases}
0166 {\cal F}_\theta & \text{(surface)} \\
0167 0 & \text{(interior)}
0168 \end{cases}
0169 \\
0bad585a21 Navi*0170 \frac{D S}{Dt} -
0171 \nabla _h \cdot (K_{h} \nabla _h S)
0172 - \frac{\partial}{\partial z}\left(\Gamma(K_{z})\frac{\partial S}{\partial z}\right)
d67096e55c Jeff*0173 &=
0174 \begin{cases}
0bad585a21 Navi*0175 {\cal F}_S & \text{(surface)} \\
d67096e55c Jeff*0176 0 & \text{(interior)}
0177 \end{cases}
0178 \\
0179
0180 .. math::
0181 g\rho_{0} \eta + \int^{0}_{-z}\rho' dz = p'
0182
0183 where :math:`u=\frac{Dx}{Dt}=r \cos(\phi)\frac{D \lambda}{Dt}` and
0184 :math:`v=\frac{Dy}{Dt}=r \frac{D \phi}{Dt}` are the zonal and
0bad585a21 Navi*0185 meridional components of the flow vector, :math:`\vec{\bf u}`, on the
d67096e55c Jeff*0186 sphere. As described in :numref:`discret_algorithm`, the time evolution of
0187 potential temperature :math:`\theta` equation is solved
0188 prognostically. The total pressure :math:`p` is diagnosed by summing
0189 pressure due to surface elevation :math:`\eta` and the hydrostatic
0190 pressure.
0191
0192 Numerical Stability Criteria
0193 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0194
0195 The Laplacian dissipation coefficient, :math:`A_{h}`, is set to
0196 :math:`5 \times 10^5` m s\ :sup:`-1`. This value is chosen to yield a Munk
0197 layer width (see Adcroft 1995 :cite:`adcroft:95`),
0198
0199 .. math::
0bad585a21 Navi*0200 M = \pi ( \frac { A_{h} }{ \beta } )^{\frac{1}{3}}
d67096e55c Jeff*0201 :label: eq:eg-global-munk_layer
0202
0203 of ~600 km. This is greater than
0204 the model resolution in low-latitudes,
0205 :math:`\Delta x \approx` 400 km, ensuring that the frictional
0206 boundary layer is adequately resolved.
0207
0208 The model is stepped forward with a time step
0209 :math:`\Delta
0210 t_{\theta}` = 24 hours for thermodynamic variables and
0211 :math:`\Delta t_{v}` = 30 minutes for momentum terms. With this time step, the
0212 stability parameter to the horizontal Laplacian friction
0213 (Adcroft 1995 :cite:`adcroft:95`)
0214
0215 .. math::
0bad585a21 Navi*0216 S_{\rm Lh} = 4 \frac{A_{h} \Delta t_{v}}{{\Delta x}^2}
d67096e55c Jeff*0217 :label: eq:eg-global-laplacian_stability
0218
0219 evaluates to 0.6 at a latitude of
0220 :math:`\phi` = 80\ :sup:`o`, which is above the 0.3 upper limit for
0221 stability, but the zonal grid spacing :math:`\Delta x` is smallest at
0222 :math:`\phi` = 80\ :sup:`o` where :math:`\Delta
0223 x=r\cos(\phi)\Delta \phi\approx` 77 km and the stability criterion
0224 is already met one grid cell equatorwards (at :math:`\phi` = 76\ :sup:`o`).
0225
0226 The vertical dissipation coefficient,
0227 :math:`A_{z}`, is set to :math:`1\times10^{-3}` m\ :sup:`2` s\ :sup:`-1`.
0228 The associated stability limit
0229
0230 .. math::
0bad585a21 Navi*0231 S_{\rm Lv} = 4 \frac{A_{z} \Delta t_{v}}{{\Delta z}^2}
d67096e55c Jeff*0232 :label: eg-global-laplacian_stability_z
0233
0234 evaluates to 0.0029 for the smallest
0235 model level spacing (:math:`\Delta z_{1}` = 50 m) which is well
0236 below the upper stability limit.
0237
0238 The numerical stability for inertial
0239 oscillations (Adcroft 1995 :cite:`adcroft:95`)
0240
0241 .. math::
0bad585a21 Navi*0242 S_{\rm inert} = f^{2} {\Delta t_v}^2
d67096e55c Jeff*0243 :label: eg-global-inertial_stability
0244
0245 evaluates to 0.07 for
0246 :math:`f=2\omega\sin(80^{\circ})=1.43\times10^{-4}` s\ :sup:`-1`,
0247 which is below the :math:`S_{i} < 1` upper limit for stability.
0248
0249 The advective CFL (Adcroft 1995 :cite:`adcroft:95`)
0250 for a extreme maximum horizontal flow
0bad585a21 Navi*0251 speed of :math:`| \vec{\bf u} |` = 2 m s\ :sup:`-1`
d67096e55c Jeff*0252
0253 .. math::
0bad585a21 Navi*0254 S_{\rm adv} = \frac{| \vec{\bf u} | \Delta t_{v}}{ \Delta x}
d67096e55c Jeff*0255 :label: eg-global-cfl_stability
0256
0257 evaluates to :math:`5 \times 10^{-2}`. This is
0258 well below the stability limit of 0.5.
0259
0260 The stability parameter for internal gravity
0261 waves propagating with a maximum speed of
0262 :math:`c_{g}` = 10 m s\ :sup:`-1` (Adcroft 1995 :cite:`adcroft:95`)
0263
0264 .. math::
0265 S_{c} = \frac{c_{g} \Delta t_{v}}{ \Delta x}
0266 :label: eg-global-gfl_stability
0267
0268 evaluates to :math:`2.3 \times 10^{-1}`. This is
0269 close to the linear stability limit of 0.5.
0270
0271 .. _sec_eg-global-clim_ocn_examp_exp_config:
0272
0273 Experiment Configuration
0274 ------------------------
0275
0276 The experiment files
0277
0278 - :filelink:`verification/tutorial_global_oce_latlon/input/data`
0279
0280 - :filelink:`verification/tutorial_global_oce_latlon/input/data.pkg`
0281
0282 - :filelink:`verification/tutorial_global_oce_latlon/input/eedata`
0283
0284 - ``verification/tutorial_global_oce_latlon/input/trenberth_taux.bin``
0285
0286 - ``verification/tutorial_global_oce_latlon/input/trenberth_tauy.bin``
0287
0288 - ``verification/tutorial_global_oce_latlon/input/lev_s.bin``
0289
0290 - ``verification/tutorial_global_oce_latlon/input/lev_t.bin``
0291
0292 - ``verification/tutorial_global_oce_latlon/input/lev_sss.bin``
0293
0294 - ``verification/tutorial_global_oce_latlon/input/lev_sst.bin``
0295
0296 - ``verification/tutorial_global_oce_latlon/input/bathymetry.bin``
0297
0298 - :filelink:`verification/tutorial_global_oce_latlon/code/SIZE.h`
0299
0300 contain the code customizations and parameter settings for these
0301 experiments. Below we describe the customizations to these files
0302 associated with this experiment.
0303
0304 Driving Datasets
0305 ~~~~~~~~~~~~~~~~
0306
0307 :numref:`fig_sim_config_tclim`-:numref:`fig_sim_config_emp`
0308 show the relaxation temperature (:math:`\theta^{\ast}`) and salinity
0309 (:math:`S^{\ast}`) fields, the wind stress components (:math:`\tau_x`
0310 and :math:`\tau_y`), the heat flux (:math:`Q`) and the net fresh water
0311 flux (:math:`{\cal E} - {\cal P} - {\cal R}`) used in equations
0312 :eq:`eg-global_forcing-Fu`-:eq:`eg-global_forcing-Fs`.
0313 The figures also indicate the lateral extent and coastline used in the
0314 experiment. Figure (*— missing figure —* ) shows the depth contours of
0315 the model domain.
0316
0317 .. figure:: figs/sst.png
0318 :width: 94%
0319 :align: center
0320 :alt: restoring sst field
0321 :name: fig_sim_config_tclim
0322
0323 Annual mean of relaxation temperature (:sup:`o`\ C)
0324
0325 .. figure:: figs/sss.png
0326 :width: 90%
0327 :align: center
0328 :alt: restoring sss field
0329 :name: fig_sim_config_sclim
0330
ba0b047096 Mart*0331 Annual mean of relaxation salinity (g/kg)
d67096e55c Jeff*0332
0333 .. figure:: figs/tx.png
0334 :width: 90%
0335 :align: center
0336 :alt: forcing tau_x field
0337 :name: fig_sim_config_taux
0338
0339 Annual mean of zonal wind stress component (N m\ :sup:`-2`)
0340
0341 .. figure:: figs/ty.png
0342 :width: 90%
0343 :align: center
0344 :alt: forcing tau_y field
0345 :name: fig_sim_config_tauy
0346
0347 Annual mean of meridional wind stress component (N m\ :sup:`-2`)
0348
0349 .. figure:: ../global_oce_in_p/figs/qnet.png
0350 :width: 90%
0351 :align: center
0352 :alt: forcing qnet field
0353 :name: fig_sim_config_qnet
0354
0355 Annual mean heat flux (W m\ :sup:`-2`)
0356
0357 .. figure:: ../global_oce_in_p/figs/emp.png
0358 :width: 90%
0359 :align: center
0360 :alt: forcing emp field
0361 :name: fig_sim_config_emp
0362
0363 Annual mean freshwater flux (Evaporation-Precipitation) (m s\ :sup:`-1`)
0364
0365 File :filelink:`input/data <verification/tutorial_global_oce_latlon/input/data>`
0366 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0367
0368 .. literalinclude:: ../../../verification/tutorial_global_oce_latlon/input/data
0369 :linenos:
0370 :caption: verification/tutorial_global_oce_latlon/input/data
0371
0372 This file specifies the main parameters
0373 for the experiment. The parameters that are significant for this
0374 configuration are
0375
0376 - Lines 7-8,
0377
0378 ::
0379
0380 tRef= 15*20.,
0381 sRef= 15*35.,
0382
0383 set reference values for potential temperature and salinity at each
0384 model level in units of :sup:`o`\ C and
0385 ppt. The entries are ordered from surface to depth.
0386 Density is calculated from anomalies at each level evaluated with
0387 respect to the reference values set here.
0388
0389 - Line 9,
0390
0391 ::
0392
0393 viscAr=1.E-3,
0394
0395 this line sets the vertical Laplacian dissipation coefficient to
0396 :math:`1 \times 10^{-3}` m\ :sup:`2` s\ :sup:`-1`. Boundary conditions for
0397 this operator are specified later.
0398
0399 - Line 10,
0400
0401 ::
0402
0403 viscAh=5.E5,
0404
0405 this line sets the horizontal Laplacian frictional dissipation
0406 coefficient to :math:`5 \times 10^{5}` m\ :sup:`2` s\ :sup:`-1`. Boundary
0407 conditions for this operator are specified later.
0408
0409 - Lines 11, 13,
0410
0411 ::
0412
0413 diffKhT=0.,
0414 diffKhS=0.,
0415
0416 set the horizontal diffusion coefficient for temperature and salinity
0417 to 0, since :filelink:`pkg/gmredi` is used.
0418
0419 - Lines 12, 14,
0420
0421 ::
0422
0423 diffKrT=3.E-5,
0424 diffKrS=3.E-5,
0425
0426 set the vertical diffusion coefficient for temperature and salinity
0427 to :math:`3 \times 10^{-5}` m\ :sup:`2` s\ :sup:`-1`. The boundary
0428 condition on this operator is :math:`\frac{\partial}{\partial z}=0`
0429 at both the upper and lower boundaries.
0430
0431 - Lines 15-17,
0432
0433 ::
0434
0435 rhoConst=1035.,
0436 rhoConstFresh=1000.,
0437 eosType = 'JMD95Z',
0438
0439 set the reference densities for sea water and fresh water, and
0440 selects the equation of state (Jackett and McDougall 1995 :cite:`jackett:95`)
0441
0442 - Lines 18-19,
0443
0444 ::
0445
0446 ivdc_kappa=100.,
0447 implicitDiffusion=.TRUE.,
0448
0449 specify an “implicit diffusion” scheme with increased vertical
0450 diffusivity of 100 m\ :sup:`2`/s in case of instable
0451 stratification.
0452
0453 - Line 28,
0454
0455 ::
0456
0457 readBinaryPrec=32,
0458
0459 Sets format for reading binary input datasets containing model fields
0460 to use 32-bit representation for floating-point numbers.
0461
0462 - Line 33,
0463
0464 ::
0465
0466 cg2dMaxIters=500,
0467
0468 Sets maximum number of iterations the two-dimensional, conjugate
0469 gradient solver will use, **irrespective of convergence criteria
0470 being met**.
0471
0472 - Line 34,
0473
0474 ::
0475
0476 cg2dTargetResidual=1.E-13,
0477
0478 Sets the tolerance which the 2-D conjugate gradient
0479 solver will use to test for convergence in
0480 :eq:`elliptic-backward-free-surface` to :math:`1 \times 10^{-13}`.
0481 Solver will iterate until tolerance falls below this value or until
0482 the maximum number of solver iterations is reached.
0483
0484 - Line 39,
0485
0486 ::
0487
0488 nIter0=0,
0489
0490 Sets the starting time for the model internal time counter. When set
0491 to non-zero this option implicitly requests a checkpoint file be read
0492 for initial state. By default the checkpoint file is named according
0493 to the integer number of time step value :varlink:`nIter0`. The internal
0494 time counter works in seconds. Alternatively, :varlink:`startTime` can be
0495 set.
0496
0497 - Line 40,
0498
0499 ::
0500
0501 nTimeSteps=20,
0502
0503 Sets the time step number at which this simulation will terminate. At
0504 the end of a simulation a checkpoint file is automatically written so
0505 that a numerical experiment can consist of multiple stages.
0506 Alternatively :varlink:`endTime` can be set.
0507
0508 - Line 44,
0509
0510 ::
0511
0512 deltaTmom=1800.,
0513
0514 Sets the timestep :math:`\Delta t_{v}` used in the momentum equations
0515 to 30 minutes. See :numref:`time_stepping`.
0516
0517 - Line 45,
0518
0519 ::
0520
0521 tauCD=321428.,
0522
0523 Sets the D-grid to C-grid coupling time scale :math:`\tau_{CD}` used
0524 in the momentum equations.
0525
0526 - Lines 46-48,
0527
0528 ::
0529
0530 deltaTtracer=86400.,
0531 deltaTClock = 86400.,
0532 deltaTfreesurf= 86400.,
0533
0534 Sets the default timestep, :math:`\Delta t_{\theta}`, for tracer
0535 equations and implicit free surface equations to
0536 24 hours. See :numref:`time_stepping`.
0537
0538 - Line 76,
0539
0540 ::
0541
0542 bathyFile='bathymetry.bin'
0543
0544 This line specifies the name of the file from which the domain
0545 bathymetry is read. This file is a 2-D (:math:`x,y`) map
0546 of depths. This file is assumed to contain 32-bit binary numbers
0547 giving the depth of the model at each grid cell, ordered with the :math:`x`
0548 coordinate varying fastest. The points are ordered from low
0549 coordinate to high coordinate for both axes. The units and
0550 orientation of the depths in this file are the same as used in the
0551 MITgcm code. In this experiment, a depth of 0 m indicates a
0552 solid wall and a depth of <0 m indicates open ocean.
0553
0554 - Lines 79-80,
0555
0556 ::
0557
0558 zonalWindFile='trenberth_taux.bin'
0559 meridWindFile='trenberth_tauy.bin'
0560
0561 These lines specify the names of the files from which the :math:`x`- and :math:`y`-
0562 direction surface wind stress is read. These files are also
0563 3-D (:math:`x,y,time`) maps and are enumerated and
0564 formatted in the same manner as the bathymetry file.
0565
0566 Other lines in the file :filelink:`input/data <verification/tutorial_global_oce_latlon/input/data>`
0567 are standard values that are described in the :numref:`customize_model`.
0568
0569 File :filelink:`input/data.pkg <verification/tutorial_global_oce_latlon/input/data.pkg>`
0570 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0571
0572 This file uses standard default values and does not contain
0573 customizations for this experiment.
0574
0575 File :filelink:`input/eedata <verification/tutorial_global_oce_latlon/input/eedata>`
0576 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0577
0578 This file uses standard default values and does not contain
0579 customizations for this experiment.
0580
0581 Files ``input/trenberth_taux.bin`` and ``input/trenberth_tauy.bin``
0582 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0583
0584 The ``input/trenberth_taux.bin`` and ``input/trenberth_tauy.bin`` files
0585 specify 3-D (:math:`x,y,time`) maps of wind stress
0586 :math:`(\tau_{x},\tau_{y})`, based on values from Treberth et al. (1990) :cite:`trenberth:90`.
0587 The units are N m\ :sup:`-2`.
0588
0589 File ``input/bathymetry.bin``
0590 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0591
0592 The ``input/bathymetry.bin`` file specifies a 2-D
0593 (:math:`x,y`) map of depth values. For this experiment values range
0594 between 0 and -5200 m, and have been derived
0595 from `ETOPO5 <https://www.ngdc.noaa.gov/mgg/global/etopo5.HTML>`_. The file contains a raw binary stream of data that is
0596 enumerated in the same way as standard MITgcm 2-D horizontal arrays.
0597
0598 .. _tut_global_oce_latlon_code_size:
0599
0600 File :filelink:`code/SIZE.h <verification/tutorial_global_oce_latlon/code/SIZE.h>`
0601 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0602
0603 .. literalinclude:: ../../../verification/tutorial_global_oce_latlon/code/SIZE.h
0604 :linenos:
0605 :caption: verification/tutorial_global_oce_latlon/code/SIZE.h
0606
0607 Four lines are customized in this file for the current experiment
0608
0609 - Line 45,
0610
0611 ::
0612
0613 sNx=45,
0614
0615 this line sets the number of grid points of each tile (or sub-domain)
0616 along the :math:`x`-coordinate axis.
0617
0618 - Line 46,
0619
0620 ::
0621
0622 sNy=40,
0623
0624 this line sets the number of grid points of each tile (or sub-domain)
0625 along the :math:`y`-coordinate axis.
0626
0627 - Lines 49,51,
0628
0629 ::
0630
0631 nSx=2,
0632 nPx=1,
0633
0634 these lines set, respectively, the number of tiles per process and the number of processes
0635 along the :math:`x`-coordinate axis. Therefore,
0636 the total number of grid points along the :math:`x`-coordinate axis
0637 corresponding to the full domain extent is :math:`Nx=sNx*nSx*nPx=90`.
0638
0639 - Line 55,
0640
0641 ::
0642
0643 Nr=15
0644
0645 this line sets the vertical domain extent in grid points.
0646
