diff --git a/yt/frontends/cf_radial/data_structures.py b/yt/frontends/cf_radial/data_structures.py
index 436517b3004..1c1309510d0 100644
--- a/yt/frontends/cf_radial/data_structures.py
+++ b/yt/frontends/cf_radial/data_structures.py
@@ -310,11 +310,14 @@ def _is_valid(cls, filename: str, *args, **kwargs) -> bool:
             nc4_file = NetCDF4FileHandler(filename)
             with nc4_file.open_ds(keepweakref=True) as ds:
                 con = "Conventions"  # the attribute to check for file conventions
+                # note that the attributes here are potentially space- or
+                # comma-delimited strings, so we concatenate a single string
+                # to search for a substring.
                 cons = ""  # the value of the Conventions attribute
-                for c in [con, con.lower()]:
+                for c in [con, con.lower(), "Sub_" + con.lower()]:
                     if hasattr(ds, c):
                         cons += getattr(ds, c)
-                is_cfrad = "CF/Radial" in cons
+                is_cfrad = "CF/Radial" in cons or "CF-Radial" in cons
         except (OSError, AttributeError, ImportError):
             return False