undef

s1a-iw-grd-vv-20180311t100028-20180311t100057-020966-023fd1-001_filter

s1a-iw-grd-vh-20180311t100028-20180311t100057-020966-023fd1-002_filter

s1a-iw-grd-vh-20180311t100028-20180311t100057-020966-023fd1-002_winddir

s1a-iw-grd-vv-20180311t100028-20180311t100057-020966-023fd1-001_winddir