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Title: Derivation of total diffuse attenuation coefficient from water column temperature data and meteorological water surface fluxes: A simple management tool Authored by: Adiyanti, S. and Imberger, J. Abstract:
The total diffuse attenuation coefficient of Photosynthetically Available Radiation is derived by optimising the solution of a surface layer model (Spigel et al., 1986) to match temperature profiles measured with a precision thermistor chain; a non-linear least-squares Levenberg-Marquardt scheme is applied to optimize . The method was validated in Lake Kinneret (Israel) over 10 days in 2001, Valle de Bravo Reservoir (Mexico) on 1 July 2004 and Winamp Gulf (Kenya) on 1 May and 12 August 2005, during 10 days of field experiments. In all these tests, during periods of strong diurnal stratification, the estimated values of were mostly within 10% error of the actual direct measurements. Investigations of the sensitivity of the model revealed that the accuracy of the method depended on the resolution of the temperature, the vertical location of the thermistors on the chain and the degree of wind mixing and subsurface internal wave activity; all of these determine the rate of convergence of the optimisation scheme. The possible improvement as well as application of this method as a management tool is discussed.
Reference: Adiyanti, S. and Imberger, J., 2007, Derivation of total diffuse attenuation coefficient from water column temperature data and meteorological water surface fluxes: A simple management tool, 5(4): 293-303 Keywords: Diffuse attenuation coefficient; under-water irradiance; heat equation; surface layer |
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