Estimation of VIIRS Cloud Transparency for the Indonesian Fishing Fleet—Preliminary Results

The VIIRS boat detection (VBD) algorithm detects thousands of lit fishing vessels most nights in Indonesia. The detection numbers rise and fall tracking the lunar cycle, with peak numbers under new moon conditions. The user community had questions regarding cloud obscuration effects as it appears that many boats are detected under cloudy conditions based on the VIIRS cloud mask. We report here on a study of cloud transparency relative to the detectability of lit fishing boats in Indonesia. The study included consideration of VIIRS cloud optical thickness product and the long-wave infrared radiance. Preliminary results indicate that it is possible to delineate opaque clouds that block vessel detection and to also estimate the transparency of the clouds.