undef
s1a-iw-grd-vv-20180103t145423-20180103t145448-019991-0220d9-001_filter
s1a-iw-grd-vh-20180103t145423-20180103t145448-019991-0220d9-002_filter
s1a-iw-grd-vv-20180103t145423-20180103t145448-019991-0220d9-001_winddir
s1a-iw-grd-vh-20180103t145423-20180103t145448-019991-0220d9-002_winddir