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 ~6 m s-1 wind speeds.