Python tools are now smart about longitude format.

* Require that user specify whether longitude is in [-180, 180] format (i.e., centered around Prime Meridian) or [0, 360] format (i.e., centered around International Date Line).
* Specified as --lon-type, either 180 or 360 (respectively)
* Resolves #2017
* Resolves #3001

Author: samsrabin

python/ctsm/args_utils.py

@@ -7,8 +7,6 @@
 import logging
 import argparse
 
-from ctsm.config_utils import lon_range_0_to_360
-
 logger = logging.getLogger(__name__)
 
 
@@ -29,25 +27,3 @@ def plat_type(plat):
     if plat_out < -90 or plat_out > 90:
         raise argparse.ArgumentTypeError("ERROR: Latitude should be between -90 and 90.")
     return plat_out
-
-
-def plon_type(plon):
-    """
-    Function to define lon type for the parser and
-    convert negative longitudes to 0-360 and
-    raise error if lon is not between -180 and 360.
-
-    Args:
-        plon (str): longitude
-    Raises:
-        Error (ArgumentTypeError): when longitude is <-180 and >360.
-    Returns:
-        plon_out (float): converted longitude between 0 and 360
-    """
-    plon_float = float(plon)
-    if plon_float < -180 or plon_float > 360:
-        raise argparse.ArgumentTypeError(
-            "ERROR: Longitude should be between 0 and 360 or -180 and 180."
-        )
-    plon_out = lon_range_0_to_360(plon_float)
-    return plon_out

python/ctsm/config_utils.py

@@ -18,22 +18,21 @@
 _CONFIG_UNSET = "UNSET"
 
 
-def lon_range_0_to_360(lon_in):
+def convert_lon_0to360(lon_in):
     """
     Description
     -----------
-    Restrict longitude to 0 to 360 when given as -180 to 180.
+    Convert a longitude from [-180, 180] format (i.e., centered around Prime Meridian) to [0, 360]
+    format (i.e., centered around International Date Line).
     """
-    if -180 <= lon_in < 0:
-        raise NotImplementedError(
-            "A negative longitude suggests you input longitudes in the range [-180, 0)---"
-            "i.e., centered around the Prime Meridian. This code requires longitudes in the "
-            "range [0, 360)---i.e., starting at the International Date Line."
-        )
-    if not (0 <= lon_in <= 360 or lon_in is None):
-        errmsg = "lon_in needs to be in the range 0 to 360"
-        abort(errmsg)
-    lon_out = lon_in
+    if not -180 <= lon_in <= 180:
+        raise ValueError(f"lon_in needs to be in the range [-180, 180]: {lon_in}")
+    lon_out = 180 + lon_in
+    logger.info(
+        "Converting longitude from [-180, 180] to [0, 360]: %s to %s",
+        str(lon_in),
+        str(lon_out),
+    )
 
     return lon_out
 

python/ctsm/modify_input_files/fsurdat_modifier.py

@@ -498,6 +498,13 @@ def read_cfg_required_basic_opts(config, section, cfg_path):
         file_path=cfg_path,
         convert_to_type=float,
     )
+    lon_type = get_config_value(
+        config=config,
+        section=section,
+        item="lon_type",
+        file_path=cfg_path,
+        convert_to_type=int,
+    )
 
     landmask_file = get_config_value(
         config=config,
@@ -513,7 +520,16 @@ def read_cfg_required_basic_opts(config, section, cfg_path):
     lon_dimname = get_config_value(
         config=config, section=section, item="lon_dimname", file_path=cfg_path, can_be_unset=True
     )
-    return (lnd_lat_1, lnd_lat_2, lnd_lon_1, lnd_lon_2, landmask_file, lat_dimname, lon_dimname)
+    return (
+        lnd_lat_1,
+        lnd_lat_2,
+        lnd_lon_1,
+        lnd_lon_2,
+        landmask_file,
+        lat_dimname,
+        lon_dimname,
+        lon_type,
+    )
 
 
 def fsurdat_modifier(parser):
@@ -568,6 +584,7 @@ def fsurdat_modifier(parser):
         landmask_file,
         lat_dimname,
         lon_dimname,
+        lon_type,
     ) = read_cfg_required_basic_opts(config, section, cfg_path)
     # Create ModifyFsurdat object
     modify_fsurdat = ModifyFsurdat.init_from_file(
@@ -579,6 +596,7 @@ def fsurdat_modifier(parser):
         landmask_file,
         lat_dimname,
         lon_dimname,
+        lon_type,
     )
 
     # Read control information about the optional sections

python/ctsm/modify_input_files/mesh_mask_modifier.py

@@ -66,10 +66,11 @@ def mesh_mask_modifier(cfg_path):
     lon_varname = get_config_value(
         config=config, section=section, item="lon_varname", file_path=cfg_path
     )
+    lon_type = get_config_value(config=config, section=section, item="lon_type", file_path=cfg_path)
 
     # Create ModifyMeshMask object
     modify_mesh_mask = ModifyMeshMask.init_from_file(
-        mesh_mask_in, landmask_file, lat_dimname, lon_dimname, lat_varname, lon_varname
+        mesh_mask_in, landmask_file, lat_dimname, lon_dimname, lat_varname, lon_varname, lon_type
     )
 
     # If output file exists, abort before starting work

python/ctsm/modify_input_files/modify_fsurdat.py

@@ -14,7 +14,7 @@
 
 from ctsm.utils import abort, update_metadata
 from ctsm.git_utils import get_ctsm_git_short_hash
-from ctsm.config_utils import lon_range_0_to_360
+from ctsm.config_utils import convert_lon_0to360
 
 logger = logging.getLogger(__name__)
 
@@ -26,7 +26,7 @@ class ModifyFsurdat:
     """
 
     def __init__(
-        self, my_data, lon_1, lon_2, lat_1, lat_2, landmask_file, lat_dimname, lon_dimname
+        self, my_data, lon_1, lon_2, lat_1, lat_2, landmask_file, lat_dimname, lon_dimname, lon_type
     ):
 
         self.numurbl = 3  # Number of urban density types
@@ -36,13 +36,15 @@ def __init__(
         else:
             abort("numurbl is not a dimension on the input surface dataset file and needs to be")
 
+        self.lon_type = lon_type
         self.rectangle = self._get_rectangle(
             lon_1=lon_1,
             lon_2=lon_2,
             lat_1=lat_1,
             lat_2=lat_2,
             longxy=self.file.LONGXY,
             latixy=self.file.LATIXY,
+            lon_type=self.lon_type,
         )
 
         if landmask_file is not None:
@@ -72,23 +74,37 @@ def __init__(
 
     @classmethod
     def init_from_file(
-        cls, fsurdat_in, lon_1, lon_2, lat_1, lat_2, landmask_file, lat_dimname, lon_dimname
+        cls,
+        fsurdat_in,
+        lon_1,
+        lon_2,
+        lat_1,
+        lat_2,
+        landmask_file,
+        lat_dimname,
+        lon_dimname,
+        lon_type,
     ):
         """Initialize a ModifyFsurdat object from file fsurdat_in"""
         logger.info("Opening fsurdat_in file to be modified: %s", fsurdat_in)
         my_file = xr.open_dataset(fsurdat_in)
-        return cls(my_file, lon_1, lon_2, lat_1, lat_2, landmask_file, lat_dimname, lon_dimname)
+        return cls(
+            my_file, lon_1, lon_2, lat_1, lat_2, landmask_file, lat_dimname, lon_dimname, lon_type
+        )
 
     @staticmethod
-    def _get_rectangle(lon_1, lon_2, lat_1, lat_2, longxy, latixy):
+    def _get_rectangle(lon_1, lon_2, lat_1, lat_2, longxy, latixy, lon_type):
         """
         Description
         -----------
         """
 
         # ensure that lon ranges 0-360 in case user entered -180 to 180
-        lon_1 = lon_range_0_to_360(lon_1)
-        lon_2 = lon_range_0_to_360(lon_2)
+        if lon_type == 180:
+            lon_1 = convert_lon_0to360(lon_1)
+            lon_2 = convert_lon_0to360(lon_2)
+        elif lon_type != 360:
+            raise ValueError("lon_type must be either 180 or 360")
 
         # determine the rectangle(s)
         # TODO This is not really "nearest" for the edges but isel didn't work

python/ctsm/modify_input_files/modify_mesh_mask.py

@@ -12,7 +12,7 @@
 import xarray as xr
 
 from ctsm.utils import abort
-from ctsm.config_utils import lon_range_0_to_360
+from ctsm.config_utils import convert_lon_0to360
 
 logger = logging.getLogger(__name__)
 
@@ -29,7 +29,9 @@ class ModifyMeshMask:
     # /glade/work/slevis/git/mksurfdata_toolchain/tools/modify_input_files ...
     # ... /islas_examples/modify_fsurdat/fill_indian_ocean/
     # Read mod_lnd_props here only for consistency checks
-    def __init__(self, my_data, landmask_file, lat_dimname, lon_dimname, lat_varname, lon_varname):
+    def __init__(
+        self, my_data, landmask_file, lat_dimname, lon_dimname, lat_varname, lon_varname, lon_type
+    ):
 
         self.file = my_data
 
@@ -46,6 +48,7 @@ def __init__(self, my_data, landmask_file, lat_dimname, lon_dimname, lat_varname
         self.lonvar = self._landmask_file[lon_varname][..., :]
         self.lsmlat = self._landmask_file.dims[lat_dimname]
         self.lsmlon = self._landmask_file.dims[lon_dimname]
+        self.lon_type = lon_type
 
         lonvar_first = self.lonvar[..., 0].data.max()
         lonvar_last = self.lonvar[..., -1].data.max()
@@ -75,12 +78,14 @@ def __init__(self, my_data, landmask_file, lat_dimname, lon_dimname, lat_varname
 
     @classmethod
     def init_from_file(
-        cls, file_in, landmask_file, lat_dimname, lon_dimname, lat_varname, lon_varname
+        cls, file_in, landmask_file, lat_dimname, lon_dimname, lat_varname, lon_varname, lon_type
     ):
         """Initialize a ModifyMeshMask object from file_in"""
         logger.info("Opening file to be modified: %s", file_in)
         my_file = xr.open_dataset(file_in)
-        return cls(my_file, landmask_file, lat_dimname, lon_dimname, lat_varname, lon_varname)
+        return cls(
+            my_file, landmask_file, lat_dimname, lon_dimname, lat_varname, lon_varname, lon_type
+        )
 
     def set_mesh_mask(self, var):
         """
@@ -134,13 +139,13 @@ def set_mesh_mask(self, var):
                         + f"{len(self.latvar.sizes)}"
                     )
                     abort(errmsg)
-                # ensure lon range of 0-360 rather than -180 to 180
-                lonvar_scalar = lon_range_0_to_360(lonvar_scalar)
                 # lon and lat from the mesh file
                 lat_mesh = float(self.file["centerCoords"][ncount, 1])
                 lon_mesh = float(self.file["centerCoords"][ncount, 0])
                 # ensure lon range of 0-360 rather than -180 to 180
-                lon_mesh = lon_range_0_to_360(lon_mesh)
+                if self.lon_type == 180:
+                    lonvar_scalar = convert_lon_0to360(lonvar_scalar)
+                    lon_mesh = convert_lon_0to360(lon_mesh)
 
                 errmsg = (
                     "Must be equal: "

python/ctsm/site_and_regional/regional_case.py

@@ -154,19 +154,20 @@ def check_region_lons(self):
         Check for the regional lon bounds
         """
         if self.lon1 >= self.lon2:
-            err_msg = """
-            \n
-            ERROR: lon1 is bigger than lon2.
-            lon1 points to the westernmost longitude of the region. {}
-            lon2 points to the easternmost longitude of the region. {}
-            Please make sure lon1 is smaller than lon2.
-
-            Please note that if longitude in -180-0, the code automatically
-            convert it to 0-360.
-            """.format(
-                self.lon1, self.lon2
-            )
-            raise argparse.ArgumentTypeError(err_msg)
+            pass
+            # err_msg = """
+            # \n
+            # ERROR: lon1 is bigger than lon2.
+            # lon1 points to the westernmost longitude of the region. {}
+            # lon2 points to the easternmost longitude of the region. {}
+            # Please make sure lon1 is smaller than lon2.
+
+            # Please note that if longitude in -180-0, the code automatically
+            # convert it to 0-360.
+            # """.format(
+            #     self.lon1, self.lon2
+            # )
+            # raise argparse.ArgumentTypeError(err_msg)
 
     def check_region_lats(self):
         """