fix some cf issues

modules/amv/intercompare.py

@@ -1018,7 +1018,7 @@ def best_fit(amv_spd, amv_dir, amv_prs, amv_lat, amv_lon, fcst_spd, fcst_dir, fc
             print('AMV location lat,lon,prs ({0},{1},{2}) failed to find the min vector difference in layers around AMV'.format(amv_lat,amv_lon,amv_prs))
         return bf_data
 
-    imin = imin[0][0]
+    imin = imin[0][0]  # index of min vec diff in absolute coordinates
 
 # Use a parabolic fit to find the best-fit pressure.
 # p2 - Minimized model pressure at level imin (hPa)