Scattering and Absorption of Light in Onondaga Lake

Optical information on a water body is often required when only Secchi disk depths are available. Many limnologists and water managers have attempted to estimate diffuse light attenuation in water from Secchi depth data assuming a simple inverse relationship. However, we show theoretically that the product of Secchi depth and the diffuse attenuation coefficient is markedly dependent on the reflectance coefficient (“brightness”) of water. Data from 28 New Zealand lakes of diverse optical character demonstrated this dependence over a wide range of reflectance (1.1 to 35.9 percent). Uncritical estimation of attenuation coefficients for diffuse light from Secchi depths, using the currently available simple inverse expressions, is discouraged because of the possibility of bias.

Section: Applicationsmentioning

confidence: 99%

ESTIMATION OF OPTICAL PROPERTIES OF WATER FROM SECCHI DISK DEPTHS¹

Davies‐Colley¹,

Vant²

1988

“…The coefficients a and b can be estimated from paired determinations of kd and R (Kirk, 1981b). The scattering process has been partitioned between the "whiting" component and other scattering components according to (Effler, et at., 1984) b = b+b0 (4) where b and b0 are the scattering coefficient due to "whiting" and other particles, respectively (ml). Turbidity measurements can be used to estimate this partitioning, as a linear relationship has been found to exist between turbidity (T (NTU)) and b (Kirk, 1981b;DiToro, 1978;Weidernann and Bannister, 1986), and the turbidity associated with "whiting" can be estimated by a simple technique (Effier and Johnson, 1986).…”

Section: Related Opticsmentioning

confidence: 99%

EFFECT OF “WHITING” ON OPTICAL PROPERTIES AND TURBIDITY IN OWASCO LAKE, NEW YORK¹

Effler

Perkins

Greer

et al. 1987

Self Cite

The effects "whiting" (CaCO3 precipitate) had on the optical properties and turbidity of the epilimnion of Owasco Lake, New York, were studied during the summer of 1985. Turbidity was partitioned according to "whiting" and non-"whiting" components utilizing a simple acidification procedure. Diffuse light attenuation was partitioned according to the attenuating processes of absorption and scattering. "Whiting" was present most of the summer. Two major "whiting" events occurred that caused major increases in turbidity and the attenuation of light. "Whiting" was the principle regulator of turbidity during the study; it caused increases in light attenuation by increasing light scattering. "Whiting" events can easily be mistaken by the public for phytoplankton blooms.

“…For example, simple linear relationships between SD-1, or kd, and phytoplankton biomass have frequently been applied to address optical implications of eutrophication (e.g., Megard, et aL, 1979;Tilzer, 1983). However, the optics of many lakes cannot be modeled accurately with simple empirical expressions because of uncoupled variations in attenuating constituents or the omission of an important constituent (e.g., Effler, et aL, 1984). Deterministic frameworks, which are based on the fundamental inherent optical properties a and b (e.g., Effler, et al, 1984;Effler, et al, 1987a;Weideman and.…”

Section: Introductionmentioning

confidence: 99%

“…However, the optics of many lakes cannot be modeled accurately with simple empirical expressions because of uncoupled variations in attenuating constituents or the omission of an important constituent (e.g., Effler, et aL, 1984). Deterministic frameworks, which are based on the fundamental inherent optical properties a and b (e.g., Effler, et al, 1984;Effler, et al, 1987a;Weideman and. Bannister, 1987;Weidemann, et a!., 1985), have the capability of accommodating more complex optical regimes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A SIMPLE TECHNIQUE FOR ESTIMATING ABSORPTION AND SCATTERING COEFFICIENTS¹

Effler

Roop

Perkins

1988

Self Cite

Results from five different test systems, which include a wide range of optical conditions, indicate credible estimates of the values of the absorption and scattering coefficients can be calculated from paired measurements of Secchi disc transparency and the diffuse attenuation coefficient. The diagnostic utility of the estimates in identifying components and processes that regulate light penetration is demonstrated for three different cases. The simple estimation technique is valuable in the analysis of existing data bases that lack comprehensive optical information to develop and evaluate alternate models for light penetration and to establish the experimental needs of future field programs to support lake management efforts.