FieldSet checking and kernel compatability

[VeckoTheGecko]

In main we have check_fieldsets_in_kernels which defines restrictions on the FieldSet. I think that these can be implemented a different way directly via the kernel API in v4.

I propose that we remove check_fieldsets_in_kernels for now and implement this down the line in v4 - using this issue to track discussion.

Code

Parcels/parcels/kernel.py

Lines 320 to 381 in c42ca55

	def check_fieldsets_in_kernels(self, pyfunc):
	"""
	Checks the integrity of the fieldset with the kernels.
	This function is to be called from the derived class when setting up the 'pyfunc'.
	"""
	if self.fieldset is not None:
	if pyfunc is AdvectionRK4_3D:
	warning = False
	if (
	isinstance(self._fieldset.W, Field)
	and self._fieldset.W._creation_log != "from_nemo"
	and self._fieldset.W._scaling_factor is not None
	and self._fieldset.W._scaling_factor > 0
	):
	warning = True
	if isinstance(self._fieldset.W, NestedField):
	for f in self._fieldset.W:
	if f._creation_log != "from_nemo" and f._scaling_factor is not None and f._scaling_factor > 0:
	warning = True
	if warning:
	warnings.warn(
	"Note that in AdvectionRK4_3D, vertical velocity is assumed positive towards increasing z. "
	"If z increases downward and w is positive upward you can re-orient it downwards by setting fieldset.W.set_scaling_factor(-1.)",
	KernelWarning,
	stacklevel=2,
	)
	elif pyfunc is AdvectionAnalytical:
	if self.fieldset.particlefile is not None:
	self.fieldset.particlefile._is_analytical = True
	if self._ptype.uses_jit:
	raise NotImplementedError("Analytical Advection only works in Scipy mode")
	if self._fieldset.U.interp_method != "cgrid_velocity":
	raise NotImplementedError("Analytical Advection only works with C-grids")
	if self._fieldset.U.grid._gtype not in [GridType.CurvilinearZGrid, GridType.RectilinearZGrid]:
	raise NotImplementedError("Analytical Advection only works with Z-grids in the vertical")
	elif pyfunc is AdvectionRK45:
	if not hasattr(self.fieldset, "RK45_tol"):
	warnings.warn(
	"Setting RK45 tolerance to 10 m. Use fieldset.add_constant('RK45_tol', [distance]) to change.",
	KernelWarning,
	stacklevel=2,
	)
	self.fieldset.add_constant("RK45_tol", 10)
	if self.fieldset.U.grid.mesh == "spherical":
	self.fieldset.RK45_tol /= (
	1852 * 60
	) # TODO does not account for zonal variation in meter -> degree conversion
	if not hasattr(self.fieldset, "RK45_min_dt"):
	warnings.warn(
	"Setting RK45 minimum timestep to 1 s. Use fieldset.add_constant('RK45_min_dt', [timestep]) to change.",
	KernelWarning,
	stacklevel=2,
	)
	self.fieldset.add_constant("RK45_min_dt", 1)
	if not hasattr(self.fieldset, "RK45_max_dt"):
	warnings.warn(
	"Setting RK45 maximum timestep to 1 day. Use fieldset.add_constant('RK45_max_dt', [timestep]) to change.",
	KernelWarning,
	stacklevel=2,
	)
	self.fieldset.add_constant("RK45_max_dt", 60 * 60 * 24)

[VeckoTheGecko]

Hmm, actually this can't really be removed at the moment since it patches the FieldSet. Let's still keep this open so that we can reconsider how its done in v4