undef

s1a-iw-grd-vv-20170316t100116-20170316t100141-015716-019ddc-001_filter

s1a-iw-grd-vh-20170316t100116-20170316t100141-015716-019ddc-002_filter

s1a-iw-grd-vv-20170316t100116-20170316t100141-015716-019ddc-001_winddir