On the effects of topography on wind and the generation of currents in a large multi-basin lake

Abstract

The wind field over a lake surface is the key element in driving the exchange of momentum and energy at the free surface. It is rarely uniform, having a considerable degree of spatial variability, both on a synoptic and a local scale. Topographic features are one of the most common contributors to this variability. The aerodynamic effects of topography on the windfield, and its influence on the circulation patterns and interbasin exchange rates in a large multi-basin lake are documented. The complex landscape that surrounds this lake is dominated by the presence of a mountain peak rising over 900 m above the lake level. The circulation patterns in those basins of the lake located in the leeward side of the mountain reflect the spatial patterns of the wind field generated by the surrounding topography. The spatial variations in the wind field are shown to significantly alter the residence times of each basin and the exchange rates between basins, isolating one from the other two basins of the lake. The inter-basin exchange rates determined with wind field variability are consistent with annual contaminant loadings estimated for each of the three basins, which suggests a close link between chemical and hydrodynamic behavior.

Horizontal structure and excitation of primary motions in a strongly stratified lake

“…Wind stress curl is more important in a strongly stratified lake than in a homogeneous lake because the stratification prevents the generation of circular currents due to topographic effect in a lake's interior. The results of this study suggest that wind variability over a lake is crucial to studies of gyres in strongly stratified lakes, especially ones surrounded by complex terrain as pointed out by Rueda et al (2005).…”

“…Although thermal effects can be important on a seasonal timescale Akitomo et al 2004), recent studies indicate that, for timescales shorter than seasonal, wind stress curl and topographic effects are the major driving forces of gyres (Laval et al 2003(Laval et al , 2005Rueda et al 2005) and the contributions from internal waves are minor (Pan et al 2002). We will limit our focus to winddriven gyres in this paper.…”

“…Analytical solutions of internal waves excited by a suddenly imposed wind show that the amplitudes increase in the first half of the wave period, reach a maximum after half the period, and then decrease in the second half of the period (e.g., Birchfield 1969;Stocker and Imberger 2003). Field and modelling studies indicate that excitation or cancellation of an internal wave depends on the phase between the wave and the wind (Mortimer 1953;Antenucci et al 2000;Rueda et al 2003), and that winds not only excite internal waves but also shift their observed phase due to generation of additional internal waves (Gó mez- Giraldo et al 2006). The effectiveness of winds in excitation or cancellation also depends on the spatial distribution of the wind stress field over the lake and the horizontal structure of internal waves; however, this interplay is not well understood in an irregular basin.…”

Temporal and spatial variability of the internal wave field in a lake with complex morphometry

“…That said, Dorostkar (2012), using the hydrostatic version of Massachusetts Institute of Technology general circulation model (MITgcm) and a 113 m grid, illustrates that hydrostatic models resolve nonlinear waves as they propagate across lakes. The extent to which use of a hydrostatic model affects the fidelity of the computations can be assessed by comparing modeled and observed isotherm displacements (Hodges et al 2000;Laval et al 2003b;Rueda and Schladow 2003). We validated the model by comparing the root mean squared error (RMSE) of both isotherm displacements and temperature and by calculating Model skill estimates following Willmott (1981) as…”

The seasonal evolution of high vertical‐mode internal waves in a deep reservoir

“…The induced bottom currents contribute to the mixing and resuspension of sediments in the benthic boundary layer by transporting the products of bacterial decomposition away from the sediment-water interface into the bulk water (Gloor et al 1994). Therefore, internal waves play an important role in the ecology of aquatic systems; as a consequence, the study and description of these waves in stratified lakes has drawn a considerable amount of attention in the scientific literature (e.g., Hodges et al 2000;Antenucci and Imberger 2003;Rueda et al 2005, just to mention a few).…”