undef

s1a-iw-grd-vv-20170418t214515-20170418t214544-016204-01ac92-001_filter

s1a-iw-grd-vh-20170418t214515-20170418t214544-016204-01ac92-002_filter

s1a-iw-grd-vh-20170418t214515-20170418t214544-016204-01ac92-002_winddir

s1a-iw-grd-vv-20170418t214515-20170418t214544-016204-01ac92-001_winddir