Introduction of the variable prodlnox for EMAC (#2499)

Co-authored-by: Manuel Schlund <32543114+schlunma@users.noreply.github.com>
Co-authored-by: Manuel Schlund <manuel.schlund@dlr.de>

esmvalcore/cmor/_fixes/emac/emac.py

@@ -211,6 +211,34 @@ def fix_metadata(self, cubes):
         return CubeList([cube])
 
 
+class Prodlnox(EmacFix):
+    """Fixes for ``prodlnox``."""
+
+    def fix_metadata(self, cubes):
+        """Fix metadata."""
+        noxcg_cube = self.get_cube(
+            cubes, var_name=['NOxcg_cav', 'NOxcg_ave', 'NOxcg']
+        )
+        noxic_cube = self.get_cube(
+            cubes, var_name=['NOxic_cav', 'NOxic_ave', 'NOxic']
+        )
+        dt_cube = self.get_cube(cubes, var_name='dt')
+
+        cube = ((
+            noxcg_cube.collapsed(
+                ['longitude', 'latitude'], iris.analysis.SUM, weights=None
+            ) +
+            noxic_cube.collapsed(
+                ['longitude', 'latitude'], iris.analysis.SUM, weights=None
+            )) /
+            dt_cube
+        )
+        cube.units = 'kg s-1'
+        cube.var_name = self.vardef.short_name
+
+        return CubeList([cube])
+
+
 Evspsbl = NegateData
 
 

esmvalcore/cmor/tables/custom/CMOR_prodlnox.dat

@@ -0,0 +1,20 @@
+SOURCE: CMIP6
+!============
+variable_entry:    prodlnox
+!============
+modeling_realm:    atmos
+!----------------------------------
+! Variable attributes:
+!----------------------------------
+standard_name:
+units:             kg s-1
+long_name:         Tendency of atmosphere mass content of NOx from lightning
+comment:           Production NOX (NO+NO2) by lightning globally integrated
+!----------------------------------
+! Additional variable information:
+!----------------------------------
+dimensions:        time
+out_name:          prodlnox
+type:              real
+!----------------------------------
+!

esmvalcore/config/extra_facets/emac-mappings.yml

@@ -74,6 +74,8 @@ EMAC:
     prc:
       raw_name: [aprc_cav, aprc_ave, aprc]
       channel: Amon
+    prodlnox: # derived from NOxcg_*, NOxic_*
+      channel: Amon
     prl:  # non-CMOR variable
       raw_name: [aprl_cav, aprl_ave, aprl]
       channel: Amon

tests/integration/cmor/_fixes/emac/test_emac.py

@@ -22,6 +22,7 @@
     MP_SS_tot,
     Od550aer,
     Pr,
+    Prodlnox,
     Rlds,
     Rlus,
     Rlut,
@@ -931,6 +932,36 @@ def test_clwvi_fix(cubes_2d):
     np.testing.assert_allclose(cube.data, [[[2.0]]])
 
 
+def test_get_prodlnox_fix():
+    """Test getting of fix."""
+    fix = Fix.get_fixes('EMAC', 'EMAC', 'Amon', 'prodlnox')
+    assert fix == [Prodlnox(None), AllVars(None), GenericFix(None)]
+
+
+def test_prodlnox_fix(cubes_2d):
+    """Test fix."""
+    cubes_2d[0].var_name = 'NOxcg_cav'
+    cubes_2d[1].var_name = 'NOxic_cav'
+    cubes_2d[2].var_name = 'dt'
+    cubes_2d[0].units = 'kg'
+    cubes_2d[1].units = 'kg'
+    cubes_2d[2].units = 's'
+
+    fixed_cubes = fix_metadata(cubes_2d, 'Amon', 'prodlnox')
+
+    assert len(fixed_cubes) == 1
+    cube = fixed_cubes[0]
+    assert cube.var_name == 'prodlnox'
+    assert cube.standard_name is None
+    assert cube.long_name == (
+        'Tendency of atmosphere mass content of NOx from lightning'
+    )
+    assert cube.units == 'kg s-1'
+    assert 'positive' not in cube.attributes
+
+    np.testing.assert_allclose(cube.data, [[[2.0]]])
+
+
 def test_get_co2mass_fix():
     """Test getting of fix."""
     fix = Fix.get_fixes('EMAC', 'EMAC', 'Amon', 'co2mass')