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VERTICAL DIFFUSION IN SMALL STRATIFIED LAKES: DATA AND ERROR ANALYSIS
Citation:
Hondzo, M., C. Ellis, AND H. Stefan. VERTICAL DIFFUSION IN SMALL STRATIFIED LAKES: DATA AND ERROR ANALYSIS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-93/003 (NTIS PB93149185), 1993.
Description:
Water temperature profiles were measured at 2-min intervals in a stratified temperate lake with a surface area of 0.06 km2 and a aximum depth of 10 m from May 7 to August 9, 1989. he data were used to calculate the vertical eddy diffusion coefficient K2 in the hypolimnion. he depth is representative of a large number of lakes in the north central United States. 2 was calculated over time intervals of 1 to 15 days and varied from 10-3 to 10-1 cm2s-1. umerical model was developed for heat conduction in the sediments, and heat flux between water and sediments was incorporated into the relationship from which eddy diffusivity was estimated. eat flux between water and lake sediments, a term commonly neglected, was found to be important in the K estimation. 2 values were related to stratification stability as measured by the Brunt-Vansala frequency N using Welander's expression of the form K2 = a(N2). alues of a were on the order of 10-2 and b varied from -0.36 to -0.45 when K2 was given in cm2s-1 of sampling intervals in time and depth on the eddy diffusivity estimates were evaluated. he longest time interval (15 days) and the smallest depth increment (1m) used in this study were found to give the best K2 estimates.