undef
s1a-iw-grd-vv-20180614t131412-20180614t131437-022353-026b91-001_filter
s1a-iw-grd-vh-20180614t131412-20180614t131437-022353-026b91-002_filter
s1a-iw-grd-vv-20180614t131412-20180614t131437-022353-026b91-001_winddir
s1a-iw-grd-vh-20180614t131412-20180614t131437-022353-026b91-002_winddir