Merge remote-tracking branch 'origin/v4-dev' into feature/uxgrid-morton-hashing

Author: fluidnumericsJoe

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/_index_search.py

@@ -77,6 +77,30 @@ def curvilinear_point_in_cell(grid, y: np.ndarray, x: np.ndarray, yi: np.ndarray
 def _search_indices_curvilinear_2d(
     grid: XGrid, y: np.ndarray, x: np.ndarray, yi: np.ndarray | None = None, xi: np.ndarray | None = None
 ):
+    """Searches a grid for particle locations in 2D curvilinear coordinates.
+
+    Parameters
+    ----------
+    grid : XGrid
+        The curvilinear grid to search within.
+    y : np.ndarray
+        Array of latitude-coordinates of the points to locate.
+    x : np.ndarray
+        Array of longitude-coordinates of the points to locate.
+    yi : np.ndarray | None, optional
+        Array of initial guesses for the j indices of the points to locate.
+    xi : np.ndarray | None, optional
+        Array of initial guesses for the i indices of the points to locate.
+
+    Returns
+    -------
+    tuple
+        A tuple containing four elements:
+        - yi (np.ndarray): Array of found j-indices corresponding to the input coordinates.
+        - eta (np.ndarray): Array of barycentric coordinates in the j-direction within the found grid cells.
+        - xi (np.ndarray): Array of found i-indices corresponding to the input cooordinates.
+        - xsi (np.ndarray): Array of barycentric coordinates in the i-direction within the found grid cells.
+    """
     if np.any(xi):
         # If an initial guess is provided, we first perform a point in cell check for all guessed indices
         is_in_cell, coords = curvilinear_point_in_cell(grid, y, x, yi, xi)

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
             )