Update UxGrid axis to "FACE" instead of "CELL"

Author: VeckoTheGecko

parcels/application_kernels/interpolation.py

@@ -32,7 +32,7 @@ def UXPiecewiseConstantFace(
     This interpolation method is appropriate for fields that are
     face registered, such as u,v in FESOM.
     """
-    return field.data.values[ti, position["Z"][0], position["CELL"][0]]
+    return field.data.values[ti, position["Z"][0], position["FACE"][0]]
 
 
 def UXPiecewiseLinearNode(
@@ -51,8 +51,8 @@ def UXPiecewiseLinearNode(
     velocity W in FESOM2. Effectively, it applies barycentric interpolation in the lateral direction
     and piecewise linear interpolation in the vertical direction.
     """
-    k, fi = position["Z"][0], position["CELL"][0]
-    bcoords = position["CELL"][1]
+    k, fi = position["Z"][0], position["FACE"][0]
+    bcoords = position["FACE"][1]
     node_ids = field.grid.uxgrid.face_node_connectivity[fi, :]
     # The zi refers to the vertical layer index. The field in this routine are assumed to be defined at the vertical interface levels.
     # For interface zi, the interface indices are [zi, zi+1], so we need to use the values at zi and zi+1.

parcels/uxgrid.py

@@ -11,7 +11,7 @@
 
 from .basegrid import BaseGrid
 
-_UXGRID_AXES = Literal["Z", "CELL"]
+_UXGRID_AXES = Literal["Z", "FACE"]
 
 
 class UxGrid(BaseGrid):
@@ -83,7 +83,7 @@ def try_face(fid):
         if fi == -1:
             raise FieldOutOfBoundError(z, y, x)
 
-        return {"Z": (zi, zeta), "CELL": (fi, bcoords[0])}
+        return {"Z": (zi, zeta), "FACE": (fi, bcoords[0])}
 
     def _get_barycentric_coordinates(self, y, x, fi):
         """Checks if a point is inside a given face id on a UxGrid."""
@@ -103,9 +103,9 @@ def _get_barycentric_coordinates(self, y, x, fi):
         return bcoord, err
 
     def ravel_index(self, axis_indices: dict[_UXGRID_AXES, int]):
-        return axis_indices["CELL"] + self.uxgrid.n_face * axis_indices["Z"]
+        return axis_indices["FACE"] + self.uxgrid.n_face * axis_indices["Z"]
 
     def unravel_index(self, ei) -> dict[_UXGRID_AXES, int]:
         zi = ei // self.uxgrid.n_face
         fi = ei % self.uxgrid.n_face
-        return {"Z": zi, "CELL": fi}
+        return {"Z": zi, "FACE": fi}