undef

s1a-ew-grd-hv-20170518t154329-20170518t154429-016638-01b9bc-002_filter

s1a-ew-grd-hh-20170518t154329-20170518t154429-016638-01b9bc-001_filter

s1a-ew-grd-hv-20170518t154329-20170518t154429-016638-01b9bc-002_winddir

s1a-ew-grd-hh-20170518t154329-20170518t154429-016638-01b9bc-001_winddir