Effect of surface waves on the irradiance distribution in the upper ocean

The distribution of irradiance in the upper ocean was examined from sensors mounted on an Autonomous Underwater Vehicle ( AUV). Apparent and inherent optical properties along with physical variability ranging from scales O( 10 cm) to O( 1 km) were collected off the coast of Oregon during the summer of 2004. Horizontal wavenumber spectra of downwelling irradiance showed that irradiance varied as a function of wavenumber and depth. The analysis indicates that irradiance variability between 1 and 20 m spatial scales was attributed to the focusing effects of surface wave geometry. The dominant wavelength of focusing at depths of 2 - 6 m was about 2 m for similar to 6 m s(-1) wind speeds. (c) 2005 Optical Society of America.