Offshore Tower Shading Effects on in-Water Optical Measurements
A field campaign was performed to estimate the shading effect induced on in water irradiance and radiance measurements taken in the immediate vicinity of the Acqua Alta Oceanographic Tower (AAOT), located in the northern Adriatic Sea, which is regularly used to support ocean colour validation activities. Sequences of downwelling irradiance and upwelling radiance profiles were collected at varying distances from the tower to evaluate the shading effects during clear sky conditions as a function of the deployment distance. The experimental data, as well as Monte Carlo simulations, indicate that the shading effects during clear sky conditions as a function of the development distance. The experimental data, as well as Monte Carlo simulations, indicate that the shading effect is negligible for both downwelling irradiances and upwelling radiances at deployment distances greater than 15 m and 20 m, respectively. At closer distances for example at the 7.5 m deployment distance regularly used at the AAOT for the collection of underwater optical measurements, the shading effect is remarkable: both field and simulated data at a depth of 7 m and a wavelength of 443 nm show that, with a relatively low sun zenith angle of 22 degree, the shading effect is within 3/00 for downwelling irradiance and within 8/00 for upwelling radiance.
Bibliographic Reference: Article: Journal of Atmospheric and Oceanic Technology, 1998
Record Number: 199910276 / Last updated on: 1999-03-12
Original language: en
Available languages: en