Drop range related attributes on load (#3072)

Author: bouweandela

esmvalcore/preprocessor/_io.py

@@ -42,6 +42,28 @@
 }
 
 
+def _drop_range_attributes(cube: Cube) -> Cube:
+    """Drop range related attributes from cube and its components."""
+    drop_attrs = (
+        "actual_range",
+        "valid_max",
+        "valid_min",
+        "valid_range",
+    )
+    cube = cube.copy()
+    for attr in drop_attrs:
+        cube.attributes.pop(attr, None)
+        for coord in cube.dim_coords:
+            coord.attributes.pop(attr, None)
+        for aux_coord in cube.aux_coords:
+            aux_coord.attributes.pop(attr, None)
+        for cell_measure in cube.cell_measures():
+            cell_measure.attributes.pop(attr, None)
+        for ancillary_variable in cube.ancillary_variables():
+            ancillary_variable.attributes.pop(attr, None)
+    return cube
+
+
 def load(
     file: str
     | Path
@@ -133,7 +155,9 @@ def load(
             )
             warnings.warn(warn_msg, ESMValCoreLoadWarning, stacklevel=2)
 
-    return cubes
+    # Drop range related attributes as these are likely to be
+    # invalidated by preprocessing the data.
+    return CubeList(_drop_range_attributes(cube) for cube in cubes)
 
 
 def _load_zarr(

tests/integration/preprocessor/_io/test_load.py

@@ -9,7 +9,7 @@
 import numpy as np
 import pytest
 import xarray as xr
-from iris.coords import DimCoord
+from iris.coords import AncillaryVariable, CellMeasure, DimCoord
 from iris.cube import Cube, CubeList
 
 from esmvalcore.exceptions import ESMValCoreLoadWarning
@@ -39,6 +39,39 @@ def test_load(tmp_path, sample_cube):
     assert_array_equal(sample_cube.coord("latitude").points, [1, 2])
 
 
+def test_load_with_range_attrs(tmp_path: Path, sample_cube: Cube) -> None:
+    """Test loading multiple files."""
+    sample_cube.attributes["valid_max"] = 1
+    ancillary_var = AncillaryVariable(
+        [0, 1.1],
+        standard_name="land_area_fraction",
+        units="%",
+    )
+    ancillary_var.attributes["valid_max"] = 1
+    sample_cube.add_ancillary_variable(ancillary_var, data_dims=[0])
+    cell_measure = CellMeasure([1, 1], standard_name="cell_area", units="m2")
+    cell_measure.attributes["valid_min"] = 1
+    sample_cube.add_cell_measure(cell_measure, data_dims=[0])
+    temp_file = tmp_path / "cube.nc"
+    iris.save(sample_cube, temp_file)
+
+    cubes = load(temp_file)
+
+    assert len(cubes) == 1
+    sample_cube = cubes[0]
+    assert "valid_max" not in sample_cube.attributes
+    assert_array_equal(
+        sample_cube.data,
+        np.ma.array([1, 2], mask=[False, True]),
+    )
+    assert "valid_max" not in sample_cube.ancillary_variables()[0].attributes
+    assert_array_equal(
+        sample_cube.ancillary_variables()[0].data,
+        np.ma.array([0, 1.1], mask=[False, True]),
+    )
+    assert "valid_min" not in sample_cube.cell_measures()[0].attributes
+
+
 def test_load_grib():
     """Test loading a grib file."""
     grib_path = (