undef
s1a-iw-grd-vv-20150904t100929-20150904t100954-007564-00a768-001_filter
s1a-iw-grd-vh-20150904t100929-20150904t100954-007564-00a768-002_filter
s1a-iw-grd-vv-20150904t100929-20150904t100954-007564-00a768-001_winddir
s1a-iw-grd-vh-20150904t100929-20150904t100954-007564-00a768-002_winddir