INTENSIVELY LEARNING OPTICAL OCEANOGRAPHY: INTERPRETATION OF THE SPECTRAL SHAPES OF PARTICLE BACKSCATTERING, SAN JUAN ISLANDS, WA

The spectral shapes of backscattering were interpreted for data obtained with a HOBI Labs Hydroscat-6 aboard the R/V Barnes on August 3-5, 1998 in West Sound, East Sound, and the Strait of Juan de Fuca, Washington. Spectra of particle backscattering (bbp) deviated from exponential wavelength dependence on all three cruises. This was most likely due to the occurrence of relatively large particles as evidenced by spectral particulate attenuation, particle size distributions (measured with a Coulter Multisizer), and particle backscattering efficiencies. Semi-empirical estimates of particle backscattering spectra were calculated using Hydrolight software and measured profiles of scattering coefficients (WETLabs ac-9) and assuming a coastal ocean volume scattering function as determined by Petzold (1972). Deviations of these modelled spectra from those obtained by the Hydroscat indicate the need for spectrally-dependent phase functions in the modelling of bbp. Theoretical spectra of bbp were calculated using the anomalous diffraction approximation with inputs of the index of refraction, a particle size distribution function, and a Mie modelled volume scattering function. Iterations of the model using different size distributions showed that it is feasible to obtain spectra of bbp similar to those measured with the Hydroscat.

Day: Thursday, Feb. 4

Time:

Location: Sweeney Center

Code: SS53TH0560S