Adds Lambert Conformal support (#303)

* Adds Lambert Conformal support

* Adds standard parallel conversion from proj strings to earthkit Projections

* Makes standard parallel extraction more concise

earthkit/data/utils/projections/__init__.py

@@ -115,6 +115,12 @@ class LambertAzimuthalEqualArea(Projection):
     CARTOPY_CRS = "LambertAzimuthalEqualArea"
 
 
+class LambertConformal(Projection):
+    PROJ_NAME = "lcc"
+    CF_GRID_MAPPING_NAME = "lambert_conformal_conic"
+    CARTOPY_CRS = "LambertConformal"
+
+
 class AlbersEqualArea(Projection):
     PROJ_NAME = "aea"
     CF_GRID_MAPPING_NAME = "albers_conical_equal_area"
@@ -131,6 +137,7 @@ class Mercator(Projection):
     EquidistantCylindrical,
     LongLat,
     LambertAzimuthalEqualArea,
+    LambertConformal,
     AlbersEqualArea,
     Mercator,
 ]

earthkit/data/utils/projections/proj.py

@@ -18,6 +18,8 @@
     "proj": "proj_name",
 }
 
+STANDARD_PARALLELS = ["lat_1", "lat_2"]
+
 PROJ_PARAMS_TO_GLOBE_KWARGS = {
     "a": "semimajor_axis",
     "b": "semiminor_axis",
@@ -63,4 +65,10 @@ def to_projection_kwargs(proj_params):
     }
     kwargs["globe"] = globe_params
 
+    standard_parallels = tuple(
+        proj_params[param] for param in STANDARD_PARALLELS if param in proj_params
+    )
+    if standard_parallels:
+        kwargs["standard_parallels"] = standard_parallels
+
     return kwargs

tests/utils/test_projections.py

@@ -35,6 +35,16 @@ def test_from_proj_string_laea():
     }
 
 
+def test_from_proj_string_lcc():
+    proj_string = "+proj=lcc +lon_0=-90 +lat_1=33 +lat_2=45"
+    projection = projections.Projection.from_proj_string(proj_string)
+    assert isinstance(projection, projections.LambertConformal)
+    assert projection.parameters == {
+        "central_longitude": -90.0,
+        "standard_parallels": (33.0, 45.0),
+    }
+
+
 def test_from_cf_grid_mapping_aea():
     grid_mapping = {
         "grid_mapping_name": "albers_conical_equal_area",