Merge pull request #2140 from kgoebber/bug_fix_2137

fix bug 2137 use scale with barbs

src/metpy/plots/declarative.py

@@ -1423,8 +1423,8 @@ def griddata(self):
             if self.plot_units is not None:
                 data_subset_u = data_subset_u.metpy.convert_units(self.plot_units)
                 data_subset_v = data_subset_v.metpy.convert_units(self.plot_units)
-            self._griddata_u = data_subset_u
-            self._griddata_v = data_subset_v
+            self._griddata_u = data_subset_u * self.scale
+            self._griddata_v = data_subset_v * self.scale
 
         return (self._griddata_u, self._griddata_v)
 

tests/plots/test_declarative.py

@@ -632,6 +632,36 @@ def test_declarative_barb_gfs():
     return pc.figure
 
 
+@pytest.mark.mpl_image_compare(remove_text=True, tolerance=0.607)
+@needs_cartopy
+def test_declarative_barb_scale():
+    """Test making a contour plot."""
+    data = xr.open_dataset(get_test_data('GFS_test.nc', as_file_obj=False))
+
+    barb = BarbPlot()
+    barb.data = data
+    barb.level = 300 * units.hPa
+    barb.field = ['u-component_of_wind_isobaric', 'v-component_of_wind_isobaric']
+    barb.skip = (3, 3)
+    barb.earth_relative = False
+    barb.scale = 2
+
+    panel = MapPanel()
+    panel.area = 'us'
+    panel.projection = 'data'
+    panel.layers = ['coastline', 'borders', 'usstates']
+    panel.plots = [barb]
+
+    pc = PanelContainer()
+    pc.size = (8, 8)
+    pc.panels = [panel]
+    pc.draw()
+
+    barb.level = 700 * units.hPa
+
+    return pc.figure
+
+
 @pytest.mark.mpl_image_compare(remove_text=True, tolerance=0.466)
 @needs_cartopy
 def test_declarative_barb_gfs_knots():