Optical sun-glint surface imaging

Optical sun-glint surface imaging uses specular reflection from water to turn surface slopes and roughness into visible brightness patterns. It is useful for sea-state, coastal wave and current patterns, slick and roughness screening, and context around upper-ocean processes, but it is opportunistic rather than all-weather.^[1]

The method needs daylight, clear sky, a favourable Sun-sensor-water geometry, visible or near-infrared reflective bands, enough spatial resolution for the target wave or slick scale, and radiometry that does not saturate in the glint path. It fails when cloud, haze, aerosol, wrong geometry, land adjacency, whitecaps, or a too-smooth sea surface removes the usable contrast. Platform planning is constrained by orbit geometry and acquisition timing; high-resolution coastal imagers can be excellent when the geometry occurs, but they cannot guarantee routine coverage.

Demonstrated implementations include Sentinel-2 MSI and MODIS. Sentinel-2 MSI sun-glitter imagery has been used to map coastal wave direction, height, movement, and wave-current interactions.^[2] MODIS provides broad-swath visible and infrared imaging with 250 m, 500 m, and 1000 m channels, and NASA uses MODIS-class imagery to illustrate sunglint as wave-broadened reflection from water.^[3][1] Landsat OLI and OLI-2 are capable implementations where 15-30 m visible/NIR imaging and glint geometry coincide.^[4]