Definition of the Sea Surface Infrared Sun Glitter Corridor
Abstract
Measurements of sea surface radiance were made in the 2-5.6 and 8-14 micrometers wavebands within patterns of intense specular highlights formed near the azimuth of the sun at low solar observation angles. From these measurements, an analysis of the statistical and physical nature of a sun glitter channel as presented to a low altitude observer (i.e. shipboard) was conducted. Findings showed strong correlations between wind speed and corridor width, and between wind speed and the strength of source radiance, dominated primarily by the direct solar reflected contribution to sea radiance. 8-14 micrometer radiances showed far less susceptibility to the detrimental effects of sun glitter on IR sensing systems. All patterns were gaussian in shape across the azimuthal extent of each glitter corridor. The magnitude of glinting radiances decreased with increasing depression angles, presenting an approximate half gaussian radiance distribution in elevation. A method to convert apparent radiance (as received at the sensor) to equivalent zero-range blackbody source radiance was formulated but showed weaknesses in computing the path radiance of the atmosphere intervening between the sea and the AGA 780 sensor, and in accounting for the emissivity of the sea surface as it affected the self-emitted component of sea surface source radiance.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1992
- Accession Number
- ADA257100
Entities
People
- Eric B. Moss
Organizations
- Naval Postgraduate School