Merge pull request #2711 from djhoese/feat-mirs-noaa21-coeff-handling

Add support for NOAA-21 in MiRS limb correction

satpy/readers/mirs.py

@@ -304,9 +304,10 @@ def force_time(self, key):
     def _get_coeff_filenames(self):
         """Retrieve necessary files for coefficients if needed."""
         coeff_fn = {"sea": None, "land": None}
-        if self.platform_name == "noaa-20":
-            coeff_fn["land"] = retrieve("readers/limbcoef_atmsland_noaa20.txt")
-            coeff_fn["sea"] = retrieve("readers/limbcoef_atmssea_noaa20.txt")
+        if self.platform_name.startswith("noaa"):
+            suffix = self.platform_name[-2:]
+            coeff_fn["land"] = retrieve(f"readers/limbcoef_atmsland_noaa{suffix}.txt")
+            coeff_fn["sea"] = retrieve(f"readers/limbcoef_atmssea_noaa{suffix}.txt")
         if self.platform_name == "npp":
             coeff_fn["land"] = retrieve("readers/limbcoef_atmsland_snpp.txt")
             coeff_fn["sea"] = retrieve("readers/limbcoef_atmssea_snpp.txt")
@@ -335,19 +336,21 @@ def _nan_for_dtype(data_arr_dtype):
             return np.timedelta64("NaT")
         if np.issubdtype(data_arr_dtype, np.datetime64):
             return np.datetime64("NaT")
-        return np.nan
+        return np.float32(np.nan)
 
     @staticmethod
     def _scale_data(data_arr, scale_factor, add_offset):
         """Scale data, if needed."""
         scaling_needed = not (scale_factor == 1 and add_offset == 0)
         if scaling_needed:
-            data_arr = data_arr * scale_factor + add_offset
+            data_arr = data_arr * np.float32(scale_factor) + np.float32(add_offset)
         return data_arr
 
     def _fill_data(self, data_arr, fill_value, scale_factor, add_offset):
         """Fill missing data with NaN."""
         if fill_value is not None:
+            # NOTE: Sfc_type and other category products are not detected or handled properly
+            #   and will be converted from integers to 32-bit floats in this step
             fill_value = self._scale_data(fill_value, scale_factor, add_offset)
             fill_out = self._nan_for_dtype(data_arr.dtype)
             data_arr = data_arr.where(data_arr != fill_value, fill_out)
@@ -372,7 +375,7 @@ def apply_attributes(self, data, ds_info):
 
         """
         try:
-            global_attr_fill = self.nc.missing_value
+            global_attr_fill = self.nc.attrs["missing_value"]
         except AttributeError:
             global_attr_fill = 1.0