Make xgcm a dependency and remove vendored code

environment.yml

@@ -18,6 +18,7 @@ dependencies: #! Keep in sync with [tool.pixi.dependencies] in pyproject.toml
  - scikit-learn
  - zarr>=2.11.0,!=2.18.0,<3
  - uxarray>=2025.3.0
+ - xgcm>=0.9.0
  - pooch
 
  # Notebooks

parcels/fieldset.py

@@ -6,8 +6,8 @@
 
 import numpy as np
 import xarray as xr
+import xgcm
 
-from parcels import xgcm
 from parcels._core.utils.time import get_datetime_type_calendar
 from parcels._core.utils.time import is_compatible as datetime_is_compatible
 from parcels._typing import Mesh
@@ -130,14 +130,12 @@ def add_constant_field(self, name: str, value, mesh: Mesh = "flat"):
  correction for zonal velocity U near the poles.
  2. flat: No conversion, lat/lon are assumed to be in m.
  """
- da = xr.DataArray(
- data=np.full((1, 1, 1, 1), value),
- )
- grid = XGrid(xgcm.Grid(da))
+ ds = xr.Dataset({name: (["time", "lat", "lon", "depth"], np.full((1, 1, 1, 1), value))})
+ grid = XGrid(xgcm.Grid(ds))
  self.add_field(
  Field(
  name,
-da,
+ds[name],
  grid,
  interp_method=None, # TODO : Need to define an interpolation method for constants
  )