Friday, 7 June 2002
Observations of Reflectance Distribution around Sunglint
A scanning spectral photometer is deployed on a rigid coastal ocean platform to measure
upwelling solar radiances from the sea surface at nine elevation angles spanning 150° of
azimuth. Measured radiance distributions at 500 nm wavelength have been compared with
traditional model simulations employing the Cox and Munk distribution of wave slopes. The
model captures the general features of the observed angular reflectance distributions,
but: (a) the observed peak value of sunglint near the specular direction is larger than
simulated, except for very calm sea; the model-measurement differences increase with wind
speed and are largest for low solar elevation; (b) the observed sunglint is wider than
simulated. In contrast to some previous studies, our results do not show a clear
dependence of the mean square sea-surface slope on stability (air-sea temperature
difference).
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