Fix positive attributes in custom CMOR variables

esmvalcore/cmor/tables/custom/CMOR_clhmtisccp.dat

@@ -17,6 +17,5 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_clhtkisccp.dat

@@ -17,6 +17,5 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_cllmtisccp.dat

@@ -17,6 +17,5 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_clltkisccp.dat

@@ -17,6 +17,5 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_clmmtisccp.dat

@@ -17,6 +17,5 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_clmtkisccp.dat

@@ -17,6 +17,5 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_lwcre.dat

@@ -17,6 +17,6 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
+positive:          down
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_netcre.dat

@@ -17,6 +17,6 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
+positive:          down
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_rsnt.dat

@@ -17,6 +17,6 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
+positive:          down
 !----------------------------------
 !

esmvalcore/cmor/tables/custom/CMOR_swcre.dat

@@ -17,6 +17,6 @@ comment:           at the top of the atmosphere (to be compared with satellite m
 !----------------------------------
 dimensions:        longitude latitude time
 type:              real
-positive:          up
+positive:          down
 !----------------------------------
 !

esmvalcore/preprocessor/_derive/lwcre.py

@@ -31,5 +31,6 @@ def calculate(cubes):
 
         lwcre_cube = rlutcs_cube - rlut_cube
         lwcre_cube.units = rlut_cube.units
+        lwcre_cube.attributes['positive'] = 'down'
 
         return lwcre_cube

esmvalcore/preprocessor/_derive/netcre.py

@@ -43,5 +43,6 @@ def calculate(cubes):
 
         netcre_cube = lwcre_cube + swcre_cube
         netcre_cube.units = lwcre_cube.units
+        netcre_cube.attributes['positive'] = 'down'
 
         return netcre_cube

esmvalcore/preprocessor/_derive/rsnt.py

@@ -30,5 +30,7 @@ def calculate(cubes):
             Constraint(name='toa_outgoing_shortwave_flux'))
 
         rsnt_cube = rsdt_cube - rsut_cube
+        rsnt_cube.units = rsdt_cube.units
+        rsnt_cube.attributes['positive'] = 'down'
 
         return rsnt_cube

esmvalcore/preprocessor/_derive/swcre.py

@@ -30,5 +30,7 @@ def calculate(cubes):
             Constraint(name='toa_outgoing_shortwave_flux_assuming_clear_sky'))
 
         swcre_cube = rsutcs_cube - rsut_cube
+        swcre_cube.units = rsut_cube.units
+        swcre_cube.attributes['positive'] = 'down'
 
         return swcre_cube

tests/unit/preprocessor/_derive/test_lwcre.py

@@ -0,0 +1,28 @@
+"""Test derivation of `lwcre`."""
+import numpy as np
+import pytest
+from iris.cube import Cube, CubeList
+
+import esmvalcore.preprocessor._derive.lwcre as lwcre
+
+
+@pytest.fixture
+def cubes():
+    rlut_cube = Cube(
+        3, standard_name='toa_outgoing_longwave_flux', units='W m-2'
+    )
+    rlutcs_cube = Cube(
+        1,
+        standard_name='toa_outgoing_longwave_flux_assuming_clear_sky',
+        units='W m-2',
+    )
+    return CubeList([rlut_cube, rlutcs_cube])
+
+
+def test_lwcre_calculation(cubes):
+    """Test calculation of `lwcre`."""
+    derived_var = lwcre.DerivedVariable()
+    out_cube = derived_var.calculate(cubes)
+    np.testing.assert_equal(out_cube.data, -2)
+    assert out_cube.units == 'W m-2'
+    assert out_cube.attributes['positive'] == 'down'

tests/unit/preprocessor/_derive/test_netcre.py

@@ -0,0 +1,36 @@
+"""Test derivation of `netcre`."""
+import numpy as np
+import pytest
+from iris.cube import Cube, CubeList
+
+import esmvalcore.preprocessor._derive.netcre as netcre
+
+
+@pytest.fixture
+def cubes():
+    rlut_cube = Cube(
+        3, standard_name='toa_outgoing_longwave_flux', units='W m-2'
+    )
+    rlutcs_cube = Cube(
+        1,
+        standard_name='toa_outgoing_longwave_flux_assuming_clear_sky',
+        units='W m-2',
+    )
+    rsut_cube = Cube(
+        3, standard_name='toa_outgoing_shortwave_flux', units='W m-2'
+    )
+    rsutcs_cube = Cube(
+        1,
+        standard_name='toa_outgoing_shortwave_flux_assuming_clear_sky',
+        units='W m-2',
+    )
+    return CubeList([rlut_cube, rlutcs_cube, rsut_cube, rsutcs_cube])
+
+
+def test_netcre_calculation(cubes):
+    """Test calculation of `netcre`."""
+    derived_var = netcre.DerivedVariable()
+    out_cube = derived_var.calculate(cubes)
+    np.testing.assert_equal(out_cube.data, -4)
+    assert out_cube.units == 'W m-2'
+    assert out_cube.attributes['positive'] == 'down'

tests/unit/preprocessor/_derive/test_rsnt.py

@@ -0,0 +1,26 @@
+"""Test derivation of `rsnt`."""
+import numpy as np
+import pytest
+from iris.cube import Cube, CubeList
+
+import esmvalcore.preprocessor._derive.rsnt as rsnt
+
+
+@pytest.fixture
+def cubes():
+    rsdt_cube = Cube(
+        3, standard_name='toa_incoming_shortwave_flux', units='W m-2'
+    )
+    rsut_cube = Cube(
+        1, standard_name='toa_outgoing_shortwave_flux', units='W m-2'
+    )
+    return CubeList([rsdt_cube, rsut_cube])
+
+
+def test_rsnt_calculation(cubes):
+    """Test calculation of `rsnt`."""
+    derived_var = rsnt.DerivedVariable()
+    out_cube = derived_var.calculate(cubes)
+    np.testing.assert_equal(out_cube.data, 2)
+    assert out_cube.units == 'W m-2'
+    assert out_cube.attributes['positive'] == 'down'

tests/unit/preprocessor/_derive/test_swcre.py

@@ -0,0 +1,28 @@
+"""Test derivation of `swcre`."""
+import numpy as np
+import pytest
+from iris.cube import Cube, CubeList
+
+import esmvalcore.preprocessor._derive.swcre as swcre
+
+
+@pytest.fixture
+def cubes():
+    rsut_cube = Cube(
+        3, standard_name='toa_outgoing_shortwave_flux', units='W m-2'
+    )
+    rsutcs_cube = Cube(
+        1,
+        standard_name='toa_outgoing_shortwave_flux_assuming_clear_sky',
+        units='W m-2',
+    )
+    return CubeList([rsut_cube, rsutcs_cube])
+
+
+def test_swcre_calculation(cubes):
+    """Test calculation of `swcre`."""
+    derived_var = swcre.DerivedVariable()
+    out_cube = derived_var.calculate(cubes)
+    np.testing.assert_equal(out_cube.data, -2)
+    assert out_cube.units == 'W m-2'
+    assert out_cube.attributes['positive'] == 'down'