ENH: Added PoleRotationNetCDFCFConversion

docs/api/crs/coordinate_operation.rst

@@ -214,6 +214,15 @@ RotatedLatitudeLongitudeConversion
     :special-members: __new__
 
 
+PoleRotationNetCDFCFConversion
+----------------------------------
+
+.. autoclass:: pyproj.crs.coordinate_operation.PoleRotationNetCDFCFConversion
+    :members:
+    :show-inheritance:
+    :special-members: __new__
+
+
 ToWGS84Transformation
 ---------------------
 

docs/history.rst

@@ -7,8 +7,10 @@ Latest
 - DEP: Minimum PROJ version 8.0 (issue #940)
 - BUG: Prepend "Derived" to CRS type name if CRS is derived (issue #932)
 - BUG: Improved handling of inf values in :meth:`pyproj.transformer.Transformer.transform_bounds` (pull #961)
+- BUG: CRS CF conversions mismatch of PROJ parameters in rotated pole (issue #948)
 - ENH: Add support for transforming bounds at the poles in :meth:`pyproj.transformer.Transformer.transform_bounds` (pull #962)
 - ENH: Added :attr:`pyproj.transformer.Transformer.source_crs` & :attr:`pyproj.transformer.Transformer.target_crs` (pull #976)
+- ENH: Added :class:`pyproj.crs.coordinate_operation.PoleRotationNetCDFCFConversion` (issue #948)
 
 3.2.1
 ------

pyproj/_transformer.pyi

@@ -5,6 +5,7 @@ from pyproj._crs import _CRS, AreaOfUse, Base, CoordinateOperation
 from pyproj.enums import ProjVersion, TransformDirection
 
 proj_version_str: str
+PROJ_VERSION: Tuple[int, int, int]
 
 class AreaOfInterest(NamedTuple):
     west_lon_degree: float

pyproj/_transformer.pyx

@@ -27,6 +27,7 @@ from pyproj.exceptions import ProjError
 
 # version number string for PROJ
 proj_version_str = f"{PROJ_VERSION_MAJOR}.{PROJ_VERSION_MINOR}.{PROJ_VERSION_PATCH}"
+PROJ_VERSION = (PROJ_VERSION_MAJOR, PROJ_VERSION_MINOR, PROJ_VERSION_PATCH)
 _AUTH_CODE_RE = re.compile(r"(?P<authority>\w+)\:(?P<code>\w+)")
 
 

pyproj/crs/_cf1x8.py

@@ -23,7 +23,7 @@
     OrthographicConversion,
     PolarStereographicAConversion,
     PolarStereographicBConversion,
-    RotatedLatitudeLongitudeConversion,
+    PoleRotationNetCDFCFConversion,
     SinusoidalConversion,
     StereographicConversion,
     TransverseMercatorConversion,
@@ -333,11 +333,10 @@ def _rotated_latitude_longitude(cf_params):
     """
     http://cfconventions.org/cf-conventions/cf-conventions.html#_rotated_pole
     """
-    return RotatedLatitudeLongitudeConversion(
-        o_lat_p=cf_params["grid_north_pole_latitude"],
-        o_lon_p=cf_params["grid_north_pole_longitude"],
-        # https://github.com/pyproj4/pyproj/issues/927
-        lon_0=cf_params.get("north_pole_grid_longitude", 0.0) + 180,
+    return PoleRotationNetCDFCFConversion(
+        grid_north_pole_latitude=cf_params["grid_north_pole_latitude"],
+        grid_north_pole_longitude=cf_params["grid_north_pole_longitude"],
+        north_pole_grid_longitude=cf_params.get("north_pole_grid_longitude", 0.0),
     )
 
 
@@ -626,9 +625,9 @@ def _rotated_latitude_longitude__to_cf(conversion):
     return {
         "grid_mapping_name": "rotated_latitude_longitude",
         "grid_north_pole_latitude": params["o_lat_p"],
-        "grid_north_pole_longitude": params["o_lon_p"],
         # https://github.com/pyproj4/pyproj/issues/927
-        "north_pole_grid_longitude": params["lon_0"] - 180,
+        "grid_north_pole_longitude": params["lon_0"] - 180,
+        "north_pole_grid_longitude": params["o_lon_p"],
     }
 
 

pyproj/crs/coordinate_operation.py

@@ -9,6 +9,7 @@
 from typing import Any
 
 from pyproj._crs import CoordinateOperation
+from pyproj._transformer import PROJ_VERSION
 from pyproj.exceptions import CRSError
 
 
@@ -1444,7 +1445,7 @@ def __new__(cls, o_lat_p: float, o_lon_p: float, lon_0: float = 0.0):
             Longitude of the North pole of the unrotated source CRS,
             expressed in the rotated geographic CRS.
         lon_0: float, default=0.0
-            Longitude of projection center (lon_0).
+            Longitude of projection center.
 
         """
         rot_latlon_json = {
@@ -1461,6 +1462,68 @@ def __new__(cls, o_lat_p: float, o_lon_p: float, lon_0: float = 0.0):
         return cls.from_json_dict(rot_latlon_json)
 
 
+class PoleRotationNetCDFCFConversion(CoordinateOperation):
+    """
+    .. versionadded:: 3.3.0
+
+    Class for constructing the Pole rotation (netCDF CF convention) conversion.
+
+    http://cfconventions.org/cf-conventions/cf-conventions.html#_rotated_pole
+
+    :ref:`PROJ docs <ob_tran>`
+    """
+
+    def __new__(
+        cls,
+        grid_north_pole_latitude: float,
+        grid_north_pole_longitude: float,
+        north_pole_grid_longitude: float = 0.0,
+    ):
+        """
+        Parameters
+        ----------
+        grid_north_pole_latitude: float
+            Latitude of the North pole of the unrotated source CRS,
+            expressed in the rotated geographic CRS (o_lat_p)
+        grid_north_pole_longitude: float
+            Longitude of projection center (lon_0 - 180).
+        north_pole_grid_longitude: float, default=0.0
+            Longitude of the North pole of the unrotated source CRS,
+            expressed in the rotated geographic CRS (o_lon_p).
+        """
+        if PROJ_VERSION < (8, 2, 0):
+            # https://github.com/pyproj4/pyproj/issues/927
+            return RotatedLatitudeLongitudeConversion(
+                o_lat_p=grid_north_pole_latitude,
+                o_lon_p=north_pole_grid_longitude,
+                lon_0=grid_north_pole_longitude + 180,
+            )
+        rot_latlon_json = {
+            "$schema": "https://proj.org/schemas/v0.4/projjson.schema.json",
+            "type": "Conversion",
+            "name": "Pole rotation (netCDF CF convention)",
+            "method": {"name": "Pole rotation (netCDF CF convention)"},
+            "parameters": [
+                {
+                    "name": "Grid north pole latitude (netCDF CF convention)",
+                    "value": grid_north_pole_latitude,
+                    "unit": "degree",
+                },
+                {
+                    "name": "Grid north pole longitude (netCDF CF convention)",
+                    "value": grid_north_pole_longitude,
+                    "unit": "degree",
+                },
+                {
+                    "name": "North pole grid longitude (netCDF CF convention)",
+                    "value": north_pole_grid_longitude,
+                    "unit": "degree",
+                },
+            ],
+        }
+        return cls.from_json_dict(rot_latlon_json)
+
+
 class EquidistantCylindricalConversion(CoordinateOperation):
     """
     .. versionadded:: 2.5.0

test/crs/test_crs_cf.py

@@ -387,8 +387,8 @@ def test_cf_rotated_latlon():
         "proj": "ob_tran",
         "o_proj": "longlat",
         "o_lat_p": 32.5,
-        "o_lon_p": 170.0,
-        "lon_0": 180,
+        "o_lon_p": 0,
+        "lon_0": 350,
         "datum": "WGS84",
         "no_defs": None,
         "type": "crs",
@@ -400,8 +400,8 @@ def test_cf_rotated_latlon__grid():
         dict(
             grid_mapping_name="rotated_latitude_longitude",
             grid_north_pole_latitude=32.5,
-            grid_north_pole_longitude=170.0,
-            north_pole_grid_longitude=1.0,
+            grid_north_pole_longitude=1.0,
+            north_pole_grid_longitude=170.0,
         )
     )
     with pytest.warns(UserWarning):

test/crs/test_crs_coordinate_operation.py

@@ -21,6 +21,7 @@
     PlateCarreeConversion,
     PolarStereographicAConversion,
     PolarStereographicBConversion,
+    PoleRotationNetCDFCFConversion,
     RotatedLatitudeLongitudeConversion,
     SinusoidalConversion,
     StereographicConversion,
@@ -30,6 +31,7 @@
     VerticalPerspectiveConversion,
 )
 from pyproj.exceptions import CRSError
+from test.conftest import PROJ_GTE_82
 
 
 def _to_dict(operation):
@@ -640,6 +642,52 @@ def test_rotated_latitude_longitude_operation():
     assert _to_dict(aeaop) == {"o_lat_p": 1.0, "o_lon_p": 2.0, "lon_0": 3.0}
 
 
+def test_pole_rotation_netcdf_cf_convention__defaults():
+    poleop = PoleRotationNetCDFCFConversion(
+        grid_north_pole_latitude=1, grid_north_pole_longitude=2
+    )
+    if PROJ_GTE_82:
+        assert poleop.name == "Pole rotation (netCDF CF convention)"
+        assert poleop.method_name == "Pole rotation (netCDF CF convention)"
+        assert _to_dict(poleop) == {
+            "Grid north pole latitude (netCDF CF convention)": 1.0,
+            "Grid north pole longitude (netCDF CF convention)": 2.0,
+            "North pole grid longitude (netCDF CF convention)": 0.0,
+        }
+    else:
+        assert poleop.name == "unknown"
+        assert poleop.method_name == "PROJ ob_tran o_proj=longlat"
+        assert _to_dict(poleop) == {
+            "o_lat_p": 1.0,
+            "o_lon_p": 0.0,
+            "lon_0": 182.0,
+        }
+
+
+def test_pole_rotation_netcdf_cf_convention():
+    poleop = PoleRotationNetCDFCFConversion(
+        grid_north_pole_latitude=1,
+        grid_north_pole_longitude=2,
+        north_pole_grid_longitude=10,
+    )
+    if PROJ_GTE_82:
+        assert poleop.name == "Pole rotation (netCDF CF convention)"
+        assert poleop.method_name == "Pole rotation (netCDF CF convention)"
+        assert _to_dict(poleop) == {
+            "Grid north pole latitude (netCDF CF convention)": 1.0,
+            "Grid north pole longitude (netCDF CF convention)": 2.0,
+            "North pole grid longitude (netCDF CF convention)": 10.0,
+        }
+    else:
+        assert poleop.name == "unknown"
+        assert poleop.method_name == "PROJ ob_tran o_proj=longlat"
+        assert _to_dict(poleop) == {
+            "o_lat_p": 1.0,
+            "o_lon_p": 10.0,
+            "lon_0": 182.0,
+        }
+
+
 def test_lambert_cylindrical_equal_area_scale_operation__defaults():
     lceaop = LambertCylindricalEqualAreaScaleConversion()
     assert lceaop.name == "unknown"