Include metrics for model only run as in v2 (#949)

Author: chengzhuzhang

e3sm_diags/driver/lat_lon_driver.py

@@ -579,6 +579,7 @@ def _create_metrics_dict(
             "min": var_test.min().item(),
             "max": var_test.max().item(),
             "mean": spatial_avg(ds_test, var_key),  # type: ignore
+            "std": std(ds_test, var_key),
         },
         "unit": ds_test[var_key].attrs["units"],
     }
@@ -591,6 +592,7 @@ def _create_metrics_dict(
             "min": var_ref.min().item(),
             "max": var_ref.max().item(),
             "mean": spatial_avg(ds_ref, var_key),  # type: ignore
+            "std": std(ds_ref, var_key),
         }
 
     if ds_test_regrid is not None and ds_ref_regrid is not None:
@@ -615,6 +617,10 @@ def _create_metrics_dict(
             "corr": correlation(ds_test_regrid, ds_ref_regrid, var_key),
         }
 
+    # for model-only run
+    if ds_test is not None and ds_ref_regrid is None:
+        metrics_dict["test_regrid"] = metrics_dict["test"]
+
     if ds_diff is not None:
         var_diff = ds_diff[var_key]