Modified srhel signature to be backwards compatible.

src/wrf/computation.py

@@ -1298,7 +1298,7 @@ def dbz(pres, tkel, qv, qr, qs=None, qg=None, use_varint=False,
 
 @set_alg_metadata(2, "terrain", units="m2 s-2",
                   description="storm relative helicity")
-def srhel(u, v, height, terrain, lats=None, top=3000.0, meta=True):
+def srhel(u, v, height, terrain, top=3000.0, lats=None, meta=True):
     """Return the storm relative helicity.
     
     This function calculates storm relative helicity from WRF ARW output. 
@@ -1342,14 +1342,14 @@ def srhel(u, v, height, terrain, lats=None, top=3000.0, meta=True):
                 dimension names to the output.  Otherwise, default names will
                 be used. 
                 
+        top (:obj:`float`):  The height of the layer below which helicity is 
+            calculated (meters above ground level).
+            
         lats (:class:`xarray.DataArray` or :class:`numpy.ndarray`, optional): 
             Array of latitudes. This is required if any (or all) of your 
             domain is in the southern hemisphere. If not provided, the 
             northern hemisphere is assumed. Default is None.
 
-        top (:obj:`float`):  The height of the layer below which helicity is 
-            calculated (meters above ground level).
-
         meta (:obj:`bool`): Set to False to disable metadata and return 
             :class:`numpy.ndarray` instead of 
             :class:`xarray.DataArray`.  Default is True.