Convert prsn data from mm to cm

dp/generate_climos.py

@@ -442,11 +442,14 @@ def convert_flux_var_units(input_file, climo_data):
         flux_variable = input_file.variables[flux_var]
         units = Unit.from_udunits_str(flux_variable.units)
 
-        if units in [Unit('kg / m**2 / s'), Unit('mm / s')]:
-            logger.info("Converting {} variable to units mm/day".format(flux_var))
+        if units in [Unit('kg / m**2 / s'), Unit('mm / s'), Unit('g / cm**2 / s'), Unit('cm / s')]:
+            if units in [Unit('kg / m**2 / s'), Unit('mm / s')]:
+                logger.info("Converting {} variable to units mm/day".format(flux_var))
+            else:
+                logger.info("Converting {} variable to units cm/day".format(flux_var))
             # Update units attribute
             attributes['units'] = (units * Unit('s / day')).to_udunits_str()
-            # Multiply values by 86400 to convert from mm/s to mm/day
+            # Multiply values by 86400 to convert from mm/s to mm/day or from cm/s to cm/day
             seconds_per_day = 86400
 
             if hasattr(flux_variable, 'scale_factor') or hasattr(flux_variable, 'add_offset'):
@@ -463,7 +466,7 @@ def convert_flux_var_units(input_file, climo_data):
                 # This is not a packed file; modify the values proper
                 # Extract variable
                 var_only = cdo.select('name={}'.format(flux_var), input=climo_data)
-                # Multiply values by 86400 to convert from mm/s to mm/day
+                # Multiply values by 86400 to convert from mm/s to mm/day or from cm/s to cm/day
                 var_only = cdo.mulc(str(seconds_per_day), input=var_only)
                 # Replace pr in all-variables file
                 climo_data = cdo.replace(input=[climo_data, var_only])

dp/generate_prsn.py

@@ -95,6 +95,7 @@ def create_prsn_netcdf_from_source(src, dst, to_delete=['original_name, comment'
 
     prsn_var.standard_name = 'snowfall_flux'
     prsn_var.long_name = 'Precipitation as Snow'
+    prsn_var.units = 'g cm-2 s-1'
 
     for item in set(to_delete):
         if hasattr(prsn_var, item):
@@ -166,8 +167,14 @@ def check_pr_units(pr_units):
     valid_units = [
         Unit('kg / m**2 / s'),
         Unit('mm / s'),
+	Unit('mm / d'),
         Unit('kg / d / m**2'),
-        Unit('kg / m**2 / d')
+        Unit('kg / m**2 / d'),
+	Unit('g / cm**2 / s'),
+	Unit('cm / s'),
+	Unit('cm / d'),
+	Unit('g / d / cm**2'),
+	Unit('g / cm**2 / d')
     ]
     units = Unit.from_udunits_str(pr_units)
     return units in valid_units
@@ -222,6 +229,11 @@ def process_to_prsn(variables, output_dataset, max_chunk_len):
             }
         means = np.mean([chunk_data['tasmin'], chunk_data['tasmax']], axis=0)
         prsn_data = np.where(means < freezing, chunk_data['pr'], 0)
+
+        prsn_units_from = ureg.parse_units('kg/m^2/s')
+        prsn_units_to = ureg.parse_units('g/cm^2/s')
+        prsn_data = prsn_data * Q_(1.0, prsn_units_from).to(prsn_units_to).magnitude	
+
         output_dataset.variables['prsn'][chunk] = prsn_data
 
 

tests/test_generate_prsn.py

@@ -67,7 +67,7 @@ def test_create_prsn_netcdf_from_source(tiny_dataset, fake_dataset):
     assert np.shape(fake_dataset.variables['prsn']) == (11688, 4, 2)
     assert fake_dataset.variables['prsn'].standard_name == 'snowfall_flux'
     assert fake_dataset.variables['prsn'].long_name == 'Precipitation as Snow'
-
+    assert fake_dataset.variables['prsn'].units == 'g cm-2 s-1'
 
 @pytest.mark.parametrize('tiny_dataset, new_var, expected', [
     ('downscaled_pr', 'prsn', 'prsn_day_BCCAQ2_ACCESS1-0_ACCESS1-0+historical+rcp45+r1i1p1_r1i1p1_19600101-19911231.nc'),