from . import core
from . import _pygetm
from .constants import FILL_VALUE, CENTERS
[docs]
class Base:
"""Base class for calculating the internal pressure gradient
in x- and y-direction.
These gradients are represented by internal-pressure-associated tendencies
of layer-integrated velocity, which equal the difference between tendencies
associated with the total horizontal pressure gradient DP/dx (or DP/dy) and
those associated with the external pressure gradient, which follows from
the horizontal gradient in free surface elevation (dz/dx or dz/dy):
idpdx = -hu/rho0 * dP/dx + hu * g * dz/dx
idpdy = -hv/rho0 * dP/dy + hv * g * dz/dy
with all quantities defined at the current (tracer) time level.
Note that the rightmost terms, which remove the external pressure gradient,
will be subtracted again in the momentum equations to recover the impact of the
total pressure gradient.
"""
idpdx: core.Array
idpdy: core.Array
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def initialize(self, ugrid: core.Grid, vgrid: core.Grid):
self.idpdx = ugrid.array(
name="idpdx",
units="m2 s-2",
long_name="tendency of layer-integrated x-velocity due to internal pressure",
z=CENTERS,
fill_value=FILL_VALUE,
)
self.idpdy = vgrid.array(
name="idpdy",
units="m2 s-2",
long_name="tendency of layer-integrated y-velocity due to internal pressure",
z=CENTERS,
fill_value=FILL_VALUE,
)
[docs]
def __call__(self, buoy: core.Array):
"""Update tendencies of layer-integrated velocity due to internal pressure.
Args:
buoy: buoyancy (m s-2)
"""
raise NotImplementedError
[docs]
class Prescribed(Base):
"""Prescribed internal pressure gradient.
To set the gradients, provide arguments `idpdx` and `idpdy` when creating
an instance, or call :meth:`pygetm.core.Array.set` on the `idpdx` and `idpdy`
attributes of the instance after initialization."""
def __init__(self, idpdx: float = 0.0, idpdy: float = 0.0):
"""
Args:
idpdx: initial tendency of layer-integrated x-velocity (m2 s-2)
idpdy: initial tendency of layer-integrated y-velocity (m2 s-2)
"""
super().__init__()
self._initial_idpdx = idpdx
self._initial_idpdy = idpdy
[docs]
def initialize(self, ugrid: core.Grid, vgrid: core.Grid):
super().initialize(ugrid, vgrid)
self.idpdx.fill(self._initial_idpdx)
self.idpdy.fill(self._initial_idpdy)
def __call__(self, buoy: core.Array):
return
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class BlumbergMellor(Base):
"""Internal pressure gradient calculated as described by `Blumberg and Mellor (1987)
<https://doi.org/10.1029/CO004p0001>`_."""
def __call__(self, buoy: core.Array):
_pygetm.blumberg_mellor(buoy, self.idpdx, self.idpdy)
[docs]
class ShchepetkinMcwilliams(Base):
"""Internal pressure gradient calculated as described by `Shchepetkin and McWilliams
(2003) <https://doi.org/10.1029/2001JC001047>`_."""
def __call__(self, buoy: core.Array):
_pygetm.shchepetkin_mcwilliams(buoy, self.idpdx, self.idpdy)