Revised grib load+save

CHANGES

@@ -18,6 +18,10 @@ Features added
   OPeNDAP URLs.
 * `iris.experimental.raster.export_geotiff` now provides experimental
   GeoTiff export functionality.
+* Cubes with no vertical coordinate can now be output to Grib format. In these
+  cases, "Type of first fixed surface" is set to 1, "ground or water surface".
+  ( This is a common usage for data with no defined level, but may not be
+  strictly correct - see https://github.com/SciTools/iris/issues/519 ).
 
 Bugs fixed
 ----------

docs/iris/src/whatsnew/1.4.rst

@@ -25,6 +25,10 @@ A summary of the main features added with version 1.4:
   OPeNDAP URLs.
 * :func:`iris.experimental.raster.export_geotiff` now provides experimental
   GeoTiff export functionality.
+* Cubes with no vertical coordinate can now be output to Grib format. In these
+  cases, "Type of first fixed surface" is set to 1, "ground or water surface".
+  ( This is a common usage for data with no defined level, but may not be
+  strictly correct - see https://github.com/SciTools/iris/issues/519 ).
 
 Bugs fixed
 ----------

lib/iris/etc/grib_rules.txt

@@ -51,14 +51,15 @@ CoordAndDims(DimCoord(grib._x_points, grib._x_coord_name, units='degrees', coord
 
 
 
-####################
-### Grib1 params ###
-####################
+######################################################################
+### A few selected standard Grib1 params (none yet in grib_cf_map) ###
+######################################################################
 
 IF
 grib.edition == 1
 grib.table2Version < 128
 grib.indicatorOfParameter == 11
+grib._cf_data is None
 THEN
 CMAttribute("standard_name", "air_temperature")
 CMAttribute("units", "kelvin")
@@ -67,6 +68,7 @@ IF
 grib.edition == 1
 grib.table2Version < 128
 grib.indicatorOfParameter == 33
+grib._cf_data is None
 THEN
 CMAttribute("standard_name", "x_wind")
 CMAttribute("units", "m s-1")
@@ -75,13 +77,31 @@ IF
 grib.edition == 1
 grib.table2Version < 128
 grib.indicatorOfParameter == 34
+grib._cf_data is None
 THEN
 CMAttribute("standard_name", "y_wind")
 CMAttribute("units", "m s-1")
 
+###############################################################
+### Hook for ECMWF GRIB1 local params listed in grib_cf_map ###
+###############################################################
+
+IF
+grib.edition == 1
+grib._cf_data is not None
+THEN
+CMAttribute("standard_name", grib._cf_data.standard_name)
+CMAttribute("long_name", grib._cf_data.standard_name or grib._cf_data.long_name)
+CMAttribute("units", grib._cf_data.units)
+
+##################################################################
+### Construct magic names for otherwise unrecognised phenomena ###
+##################################################################
+
 IF
 grib.edition == 1
 grib.table2Version >= 128
+grib._cf_data is None
 THEN
 CMAttribute("long_name", "UNKNOWN LOCAL PARAM " + str(grib.indicatorOfParameter) + "." + str(grib.table2Version))
 CMAttribute("units", "???")
@@ -94,238 +114,18 @@ THEN
 CMAttribute("long_name", "UNKNOWN LOCAL PARAM " + str(grib.indicatorOfParameter) + "." + str(grib.table2Version))
 CMAttribute("units", "???")
 
-####################
-### Grib2 params ###
-####################
-
-## Note: Do we really want to be maintaining a list of these? There's lots of them...
-## Future grib  api versions may have "cfName" available for more params...
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 0
-grib.parameterNumber == 0
-THEN
-CMAttribute("standard_name", "air_temperature")
-CMAttribute("units", "kelvin")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 0
-grib.parameterNumber == 2
-THEN
-CMAttribute("standard_name", "potential_temperature")
-CMAttribute("units", "K")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 1
-grib.parameterNumber == 0
-THEN
-CMAttribute("standard_name", "specific_humidity")
-CMAttribute("units", "kg kg-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 1
-grib.parameterNumber == 1
-THEN
-CMAttribute("standard_name", "relative_humidity")
-CMAttribute("units", "%")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 1
-grib.parameterNumber == 3
-THEN
-CMAttribute("standard_name", "precipitable_water")
-CMAttribute("units", "kg m-2")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 1
-grib.parameterNumber == 22
-THEN
-CMAttribute("standard_name", "cloud_mixing_ratio")
-CMAttribute("units", "kg kg-1")
 
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 1
-grib.parameterNumber == 13
-THEN
-CMAttribute("standard_name", "water_equivalent_of_accumulated_snow_depth")
-CMAttribute("units", "kg m-2")
+#####################################
+### Grib2 params from grib_cf_map ###
+#####################################
 
 IF
 grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 2
-grib.parameterNumber == 1
+grib._cf_data is not None
 THEN
-CMAttribute("standard_name", "wind_speed")
-CMAttribute("units", "m s-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 2
-grib.parameterNumber == 2
-THEN
-CMAttribute("standard_name", "x_wind")
-CMAttribute("units", "m s-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 2
-grib.parameterNumber == 3
-THEN
-CMAttribute("standard_name", "y_wind")
-CMAttribute("units", "m s-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 2
-grib.parameterNumber == 8
-THEN
-CMAttribute("standard_name", "vertical_velocity_(pressure)")
-CMAttribute("units", "Pa s-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 2
-grib.parameterNumber == 10
-THEN
-CMAttribute("standard_name", "absolute_vorticity")
-CMAttribute("units", "s-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 3
-grib.parameterNumber == 0
-THEN
-CMAttribute("standard_name", "pressure")
-CMAttribute("units", "Pa")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 3
-grib.parameterNumber == 1
-THEN
-CMAttribute("standard_name", "pressure_reduced_to_msl")
-CMAttribute("units", "Pa")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 3
-grib.parameterNumber == 3
-THEN
-CMAttribute("standard_name", "icao_standard_atmosphere_reference_height")
-CMAttribute("units", "m")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 3
-grib.parameterNumber == 5
-THEN
-CMAttribute("standard_name", "geopotential_height")
-CMAttribute("units", "gpm")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 3
-grib.parameterNumber == 9
-THEN
-CMAttribute("standard_name", "geopotential_height_anomaly")
-CMAttribute("units", "gpm")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 6
-grib.parameterNumber == 1
-THEN
-CMAttribute("standard_name", "total_cloud_cover")
-CMAttribute("units", "%")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 6
-grib.parameterNumber == 6
-THEN
-CMAttribute("standard_name", "cloud_water")
-CMAttribute("units", "kg m-2")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 7
-grib.parameterNumber == 6
-THEN
-CMAttribute("standard_name", "convective_available_potential_energy")
-CMAttribute("units", "J kg-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 7
-grib.parameterNumber == 7
-THEN
-CMAttribute("standard_name", "convective_inhibition")
-CMAttribute("units", "J kg-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 7
-grib.parameterNumber == 8
-THEN
-CMAttribute("standard_name", "storm_relative_helicity")
-CMAttribute("units", "J kg-1")
-
-IF
-grib.edition == 2
-grib.discipline == 0
-grib.parameterCategory == 14
-grib.parameterNumber == 0
-THEN
-CMAttribute("standard_name", "total_ozone")
-CMAttribute("units", "Dobson")
-
-IF
-grib.edition == 2
-grib.discipline == 2
-grib.parameterCategory == 0
-grib.parameterNumber == 0
-THEN
-CMAttribute("standard_name", "land_cover")
-CMAttribute("units", "proportion")
-
-IF
-grib.edition == 2
-grib.discipline == 10
-grib.parameterCategory == 2
-grib.parameterNumber == 0
-THEN
-CMAttribute("standard_name", "ice_cover")
-CMAttribute("units", "proportion")
-
+CMAttribute("standard_name", grib._cf_data.standard_name)
+CMAttribute("long_name", grib._cf_data.long_name)
+CMAttribute("units", grib._cf_data.units)
 
 #######################################
 ### Grib1 verification dates ##########
@@ -557,6 +357,15 @@ grib.levelType == 'pl'
 THEN
 CoordAndDims(DimCoord(points=grib.level,  long_name="pressure", units="hPa"))
 
+# Handle grib1 phenomena which define an "implied" height value, for example
+# "2-metre temperature".  (note: Grib2 rules out such things)
+IF
+grib.edition == 1
+grib.levelType == 'sfc'
+grib._cf_data is not None
+grib._cf_data.set_height is not None
+THEN
+CoordAndDims(DimCoord(points=grib._cf_data.set_height,  long_name="height", units="m", attributes={'positive':'up'}))
 
 
 ###################
@@ -632,3 +441,5 @@ IF
 grib.productDefinitionTemplateNumber not in (0, 8)
 THEN
 CMCustomAttribute("GRIB_LOAD_WARNING",("unsupported GRIB%d ProductDefinitionTemplate: #4.%d" % (grib.edition, grib.productDefinitionTemplateNumber)))
+
+

lib/iris/fileformats/grib.py → lib/iris/fileformats/grib/__init__.py

@@ -33,8 +33,10 @@
 iris.proxy.apply_proxy('gribapi', globals())
 
 import iris.coord_systems as coord_systems
+# NOTE: careful here, to avoid circular imports (as iris imports grib)
+from iris.fileformats.grib import grib_phenom_translation as gptx
+from iris.fileformats.grib import grib_save_rules
 import iris.unit
-import grib_save_rules
 
 
 
@@ -308,7 +310,29 @@ def _compute_extra_keys(self):
             '_x_coord_name':unknown_string, '_y_coord_name':unknown_string,
             # These are here to avoid repetition in the rules files,
             # and reduce the very long line lengths.
-            '_x_points':None, '_y_points':None}
+            '_x_points':None, '_y_points':None,
+            '_cf_data':None}
+
+        # cf phenomenon translation
+        if edition == 1:
+            # Get centre code (N.B. self.centre has default type = string)
+            centre_number = gribapi.grib_get_long(self.grib_message, "centre")
+            # Look for a known grib1-to-cf translation (or None).
+            cf_data = gptx.grib1_phenom_to_cf_info(
+                table2_version=self.table2Version,
+                centre_number=centre_number,
+                param_number=self.indicatorOfParameter)
+            self.extra_keys['_cf_data'] = cf_data
+        elif edition == 2:
+            # Don't attempt to interpret params if 'master tables version' is
+            # 255, as local params may then have same codes as standard ones.
+            if self.tablesVersion != 255:
+                # Look for a known grib2-to-cf translation (or None).
+                cf_data = gptx.grib2_phenom_to_cf_info(
+                    param_discipline=self.discipline,
+                    param_category=self.parameterCategory,
+                    param_number=self.parameterNumber)
+                self.extra_keys['_cf_data'] = cf_data
 
         #reference date
         self.extra_keys['_referenceDateTime'] = \