Add VectorField.time_interval

Author: VeckoTheGecko

parcels/field.py

@@ -166,7 +166,13 @@ def __init__(
         self.name = name
         self.data = data
         self.grid = grid
-        self.time_interval = get_time_interval(data)
+        try:
+            self.time_interval = get_time_interval(data)
+        except ValueError as e:
+            e.add_note(
+                f"Error getting time interval for field {name!r}. Are you sure that the time dimension on the xarray dataset is stored as datetime or cftime datetime objects?"
+            )
+            raise e
 
         # For compatibility with parts of the codebase that rely on v3 definition of Grid.
         # Should be worked to be removed in v4
@@ -531,6 +537,13 @@ def __init__(
         self.V = V
         self.W = W
 
+        if W is None:
+            assert_same_time_interval((U, V))
+        else:
+            assert_same_time_interval((U, V, W))
+
+        self.time_interval = U.time_interval
+
         if self.W:
             self.vector_type = "3D"
         else:
@@ -670,3 +683,16 @@ def get_time_interval(data: xr.DataArray | ux.UxDataArray) -> TimeInterval | Non
         return None
 
     return TimeInterval(data.time.values[0], data.time.values[-1])
+
+
+def assert_same_time_interval(fields: list[Field]) -> None:
+    if len(fields) == 0:
+        return
+
+    reference_time_interval = fields[0].time_interval
+
+    for field in fields[1:]:
+        if field.time_interval != reference_time_interval:
+            raise ValueError(
+                f"Fields must have the same time domain. {fields[0].name}: {reference_time_interval}, {field.name}: {field.time_interval}"
+            )

tests/v4/test_field.py

@@ -105,6 +105,11 @@ def test_field_time_interval(data, grid):
     assert field.time_interval.right == np.datetime64("2001-01-01")
 
 
+def test_vectorfield_init_different_time_intervals():
+    # Tests that a VectorField raises a ValueError if the component fields have different time domains.
+    ...
+
+
 def test_field_unstructured_grid_creation(): ...