Distribution of Turbulent Kinetic Energy Dissipation in Lake Erie

Session: 47. - Physical Processes in Lakes

Shuqi Lin, Queen's University, [email protected]
Leon Boegman, Queen's University, [email protected]
Damien Bouffard, EPFL, ENAC IIE APHYS, [email protected]
Ram Yerubandi, Environment Canada, Water Sciences & Technology, Canada Centre for Inland Waters, [email protected]
Yingming Zhao, Ontario Ministry of Natural Resources, [email protected]

Abstract

Turbulence contributes to small-scale mixing and material transport in lakes. The rate of dissipation of turbulent kinetic energy (?) is one of the key parameters to quantify turbulence intensity. To understand spatial and temporal patterns of ? in Lake Erie, data from over 600 temperature microstructure casts collected at multiple stations were investigated. We used water column depth and seasonal stratification pattern to group the observations into three distinct regions (depths <10 m, 10-25 m and >25 m) and two distinct seasonal periods (stratified and mixing), with each group characterized by its unique dissipation profile. We find that for all stations, ? in the bottom boundary layer is increased by one order of magnitude and for stations with a seasonal thermocline, near-inertial waves also increase ?. In the absence of baroclinic motion, the observations over water column during nonstratified period become less quantifiable, and ? responds more directly to the wind distribution, spanning 3 orders of magnitude. Length-scales of turbulence and its dimensionless numbers were used to further investigate how physical processes affect the growth and decay of turbulent events and distribution of ? in Lake Erie. Implications of gradients in ? on resuspension of sediments and demersal fish eggs will be discussed.

1. Keyword
Lake Erie

2. Keyword
hydrodynamics

4. Additional Keyword
Turbulente kinetic energy

5. Additional Keyword
near-inertial waves

6. Additional Keyword
bottom boundary layer