(fix): use typesize on Blosc codec

changes/2962.fix.rst

@@ -0,0 +1 @@
+Internally use `typesize` constructor parameter for :class:`numcodecs.Blosc` to improve compression ratios back to the v2-package levels.

src/zarr/codecs/blosc.py

@@ -8,6 +8,7 @@
 
 import numcodecs
 from numcodecs.blosc import Blosc
+from packaging.version import Version
 
 from zarr.abc.codec import BytesBytesCodec
 from zarr.core.buffer.cpu import as_numpy_array_wrapper
@@ -163,6 +164,9 @@ def _blosc_codec(self) -> Blosc:
             "shuffle": map_shuffle_str_to_int[self.shuffle],
             "blocksize": self.blocksize,
         }
+        # See https://github.com/zarr-developers/numcodecs/pull/713
+        if Version(numcodecs.__version__) >= Version("0.16.0"):
+            config_dict["typesize"] = self.typesize
         return Blosc.from_config(config_dict)
 
     async def _decode_single(