diff --git a/openwind/sar_wind.py b/openwind/sar_wind.py
index 46e9008..2d9176b 100755
--- a/openwind/sar_wind.py
+++ b/openwind/sar_wind.py
@@ -80,7 +80,8 @@ def __init__(self, sar_image, wind_direction='ncep_wind_online',
 
         self.SAR_image_time = self.get_time(
                 self.sigma0_bandNo).replace(tzinfo=None)
-        self._set_wind_direction_source(wind_direction)
+        if not self.get_metadata().has_key('WIND_DIRECTION_SOURCE'):
+            self._set_wind_direction_source(wind_direction)
 
         if pixelsize != 'fullres':
             print 'Resizing SAR image to ' + str(pixelsize) + ' m pixel size'