diff --git a/swash/processing/read_swash.py b/swash/processing/read_swash.py
index 722ffec..53c82a9 100644
--- a/swash/processing/read_swash.py
+++ b/swash/processing/read_swash.py
@@ -10,11 +10,10 @@ class ReadSwash:
         self._n_t = None
         self._t = None
         self._x = None
-        self._data = {}
 
     @classmethod
     def read_nohead(cls, path):
-        with tempfile.NamedTemporaryFile(dir=path.parent) as tmpfile:
+        with tempfile.TemporaryFile() as tmpfile:
             with open(path) as file:
                 subprocess.run(("tr", "-d", "\n"), stdin=file, stdout=tmpfile)
             tmpfile.seek(0)
@@ -32,28 +31,17 @@ class ReadSwash:
 
     def read_scalar(self, path, const=False):
         if const:
-            self._data[path.stem] = self.read_nohead(path).reshape(
-                (self._n_t, self._n_x)
-            )[0, :]
-            return
-        self._data[path.stem] = self.read_nohead(path).reshape(
-            (self._n_t, self._n_x)
-        )
+            return self.read_nohead(path).reshape((self._n_t, self._n_x))[0, :]
+        return self.read_nohead(path).reshape((self._n_t, self._n_x))
 
     def read_vector(self, path):
-        self._data[path.stem] = self.read_nohead(path).reshape(
-            (self._n_t, 2, self._n_x)
-        )
+        return self.read_nohead(path).reshape((self._n_t, 2, self._n_x))
 
     def read_scalar_lay(self, path):
-        self._data[path.stem] = self.read_nohead(path).reshape(
-            (self._n_t, -1, self._n_x)
-        )
+        return self.read_nohead(path).reshape((self._n_t, -1, self._n_x))
 
     def read_vector_lay(self, path):
-        self._data[path.stem] = self.read_nohead(path).reshape(
-            (self._n_t, 2, -1, self._n_x)
-        )
+        return self.read_nohead(path).reshape((self._n_t, 2, -1, self._n_x))
 
     @property
     def t(self):
@@ -62,7 +50,3 @@ class ReadSwash:
     @property
     def x(self):
         return self._x
-
-    @property
-    def data(self):
-        return self._data
diff --git a/swash/processing/sws_npz.py b/swash/processing/sws_npz.py
index 0e12d5d..32622d4 100644
--- a/swash/processing/sws_npz.py
+++ b/swash/processing/sws_npz.py
@@ -27,20 +27,27 @@ rsws = ReadSwash()
 rsws.read_time(sws_out.joinpath("tsec.dat"))
 rsws.read_x(sws_out.joinpath("xp.dat"))
 
+inp.mkdir(exist_ok=True)
+log.info(f"Wrinting output in '{inp}'")
 log.info("Reading 'dep'")
-rsws.read_scalar(sws_out.joinpath("dep.dat"))
+np.save(inp.joinpath("dep"), rsws.read_scalar(sws_out.joinpath("dep.dat")))
 log.info("Reading 'botl'")
-rsws.read_scalar(sws_out.joinpath("botl.dat"), const=True)
+np.save(
+    inp.joinpath("botl"),
+    rsws.read_scalar(sws_out.joinpath("botl.dat"), const=True),
+)
 log.info("Reading 'watl'")
-rsws.read_scalar(sws_out.joinpath("watl.dat"))
+np.save(inp.joinpath("watl"), rsws.read_scalar(sws_out.joinpath("watl.dat")))
 log.info("Reading 'vel'")
-rsws.read_vector(sws_out.joinpath("vel.dat"))
+np.save(inp.joinpath("vel"), rsws.read_vector(sws_out.joinpath("vel.dat")))
 log.info("Reading 'press'")
-rsws.read_scalar(sws_out.joinpath("press.dat"))
+np.save(inp.joinpath("press"), rsws.read_scalar(sws_out.joinpath("press.dat")))
 log.info("Reading 'zk'")
-rsws.read_scalar_lay(sws_out.joinpath("zk.dat"))
+np.save(inp.joinpath("zk"), rsws.read_scalar_lay(sws_out.joinpath("zk.dat")))
 log.info("Reading 'velk'")
-rsws.read_vector_lay(sws_out.joinpath("velk.dat"))
+np.save(
+    inp.joinpath("velk"), rsws.read_vector_lay(sws_out.joinpath("velk.dat"))
+)
 
 log.info(f"Writing npz file in '{inp}'")
 inp.mkdir(exist_ok=True)