Vertical eddy diffusion calculated by the flux gradient method: Significance of sediment - water heat exchange

Abstract

Periodically measured temperature profiles were used to calculate vertical eddy diffusivities by the heat flux gradient method in the stratified portion of a dimictic New England lake. Loss of heat from the water column to sediments, a term commonly neglected, was explicitly calculated with a simple numerical model. This term dominated the heat budget of the stratified lake and would have caused large errors in calculated eddy diffusivities had it been ignored. Heat exchange with sediments should be considered when thermal flux gradient analysis is used to calculate eddy diffusion coefficients for lakes with combined metalimnetic plus hypolimnetic thicknesses up to ∼15 m.