Estimation of specific absorption coefficients of turbid coastal water constituents using the AC-9 and asymptotic attenuation coefficients

Hans Hakvoort; Roland Doerffer

doi:10.1117/12.266480

6 February 1997 Estimation of specific absorption coefficients of turbid coastal water constituents using the AC-9 and asymptotic attenuation coefficients

Hans Hakvoort, Roland Doerffer

Author Affiliations +

Proceedings Volume 2963, Ocean Optics XIII; (1997) https://doi.org/10.1117/12.266480
Event: Ocean Optics XIII, 1996, Halifax, Nova Scotia, Canada

Abstract

The inherent absorption coefficients of water constituents in the southern part of the North Sea were spectrally estimated using data from as AC-9 and the asymptotic attenuation coefficients. The 'standard' procedure of Zaneveld was used to calculate the inherent absorption coefficients from AC-9 measurements. The asymptotic coefficients were obtained from irradiance depth profiles measured with a SeaWiFS profiling multichannel radiometer. The relationship between the single scattering albedo and asymptotic attenuation was calculated with Mobley's radiative transfer model Hydrolight 3.0 for different single scattering albedo using the San Diego volume scattering function . This relation was used to calculate the inherent absorption. The absorption coefficients calculated with both methods matched for water bodies dominated by phytoplanktonic constituents. The 'standard' correction procedure for the AC-9 overcorrected for the scattering error in water bodies having higher concentrations of suspended sediment which is typical for the studied area. A negative absorption in the 500-550 nm wavelength range is obtained. Also, the 'standard' correction assumes a zero absorption at 715 nm and does not distinguish between absorption and the scattering error in this wavelength range. Using the asymptotic attenuation to estimate of inherent absorption occasionally results in an underestimation of the absorption in the 600-700 nm wavelength range. Negative absorption may be due to an inaccuracy in the estimation of the asymptotic attenuation in the red wavelength range. The specific absorption coefficients of the water constituents were calculated from the AC-9 measurements using an optimization procedure. The specific absorption coefficients as estimated by the different techniques are compared and discussed.

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Hans Hakvoort and Roland Doerffer "Estimation of specific absorption coefficients of turbid coastal water constituents using the AC-9 and asymptotic attenuation coefficients", Proc. SPIE 2963, Ocean Optics XIII, (6 February 1997); https://doi.org/10.1117/12.266480

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