undef
s1a-iw-grd-vh-20170921t224446-20170921t224511-018480-01f204-002_filter
s1a-iw-grd-vv-20170921t224446-20170921t224511-018480-01f204-001_filter
s1a-iw-grd-vv-20170921t224446-20170921t224511-018480-01f204-001_winddir
s1a-iw-grd-vh-20170921t224446-20170921t224511-018480-01f204-002_winddir