Add min temperature diagnostic into workflow

Author: daflack

src/CSET/cset_workflow/meta/diagnostics/rose-meta.conf

@@ -941,7 +941,20 @@ description=IMPACT-BASED DIAGNOSTIC.
 help=This diagnostic identifies the daily minimum temperature at each grid point.
 type=python_boolean
 compulsory=true
-sort-key=dw9
+sort-key=dw12
+
+[template variables=DAILY_09_MINIMUM_TEMPERATURE_SPATIAL_DIFFERENCE]
+ns=Diagnostics/Derived/Daily
+title=Daily minimum temperature: spatial difference
+description=IMPACT-BASED DIAGNOSTIC.
+            Determines the daily minimum temperature defined between 0900 UTC
+            and 0900 UTC the following day and takes the difference between
+            two models. Requires temperature_at_screen_level with cell_method
+            of minimum.
+help=This diangostic identifies the daily minimum temperature at each grid point.
+type=python_boolean
+compulsory=true
+sort-key=dw13
 
 ###################################
 # Aviation

src/CSET/cset_workflow/rose-suite.conf.example

@@ -21,6 +21,7 @@ CSET_MODEL_COUNT=1
 DAILY_09_MAXIMUM_TEMPERATURE_SPATIAL_PLOT=False
 DAILY_09_MAXIMUM_TEMPERATURE_SPATIAL_DIFFERENCE=False
 DAILY_09_MINIMUM_TEMPERATURE_SPATIAL_PLOT=False
+DAILY_09_MINIMUM_TEMPERATURE_SPATIAL_DIFFERENCE=False
 DETERMINISTIC_PLOT_CAPE_RATIO=False
 DETERMINISTIC_PLOT_INFLOW_PROPERTIES=False
 EXTRACT_MLEVEL_TRANSECT=False

src/CSET/loaders/spatial_difference_field.py

@@ -246,6 +246,24 @@ def load(conf: Config):
                 aggregation=False,
             )
 
+    # Daily minimum temperature.
+    if conf.DAILY_09_MINIMUM_TEMPERATURE_SPATIAL_DIFFERENCE:
+        base_model = models[0]
+        for model in models[1:]:
+            yield RawRecipe(
+                recipe="daily_09_minimum_temperature_spatial_difference.yaml",
+                variables={
+                    "BASE_MODEL": base_model["name"],
+                    "OTHER_MODEL": model["name"],
+                    "SUBAREA_TYPE": conf.SUBAREA_TYPE if conf.SELECT_SUBAREA else None,
+                    "SUBAREA_EXTENT": conf.SUBAREA_EXTENT
+                    if conf.SELECT_SUBAREA
+                    else None,
+                },
+                model_ids=[base_model["id"], model["id"]],
+                aggregation=False,
+            )
+
     # Create a list of case aggregation types.
     AGGREGATION_TYPES = ["lead_time", "hour_of_day", "validity_time", "all"]