3D Flow Structures During Upwelling Events in Lakes of Moderate Size

Abstract

Upwelling can impact water quality dynamics in stratified water bodies. Conceptual models generally classify the upwelling response to winds in lakes into either a non‐rotational (2D, closed‐basin) model or a rotational (coastal upwelling) counterpart. The non‐rotational model is broadly applied in rotationally influenced lakes. The upwelling response to winds in stratified lakes may exhibit elements of both conceptual models. Here, we present the results of simulations with an accurate three‐dimensional numerical model of a lake of moderate size (Lake Tahoe, California–Nevada, USA), and focus our analyses on addressing the influence of the Coriolis force during the upwelling setup and relaxation phases. Upwelling was observed at the upwind boundary as well as along the coast to the left of the mean wind direction due to Ekman‐driven divergence. On the downwind shoreline, where downwelling occurs, alongshore currents appeared in response to wind forcing. Following the relaxation of the wind, our simulations reveal, for the first time, the existence of powerful cyclonic alongshore currents in lakes of moderate size, which are found to be in quasi‐geostrophic balance. These currents followed the characteristics of coastal jets often observed in large lakes and the coastal ocean. Our work leads us to conclude that upwelling setup in lakes with length scales ≈20 km and Burger numbers S < 1, exhibits a combination of dynamics predicted by both the non‐rotational, 2D, closed basin model, and the rotational coastal‐upwelling conceptual model.

Fast Prediction of Solute Concentration Field in Rotationally Influenced Fluids Using a Parameter-Based Field Reconstruction Convolutional Neural Network

“…Wastewater effluents, riverine plumes, and cooling water are often discharged into large-scale water bodies, and the prediction of the relevant mixing and solute transport processes is important for assessing the relevant environmental and ecological effects and is also of significant importance in hydrodynamic, coastal, and offshore engineering [1][2][3][4]. For example, nutrients, sediment, and contaminants are often carried by rivers into large lakes, estuaries, or coastal oceans [5][6][7][8], and improper disposal of effluents significantly jeopardizes the ecology and environment of the receiving water bodies [9][10][11]. In addition, the incoming flows for many water-supply reservoirs are directed into storage in the form of turbulent jets, and a better understanding of the momentum and entrainment processes is necessary for predictions of the stratification and circulation of the general body of water, and these predictions are required for water quality analysis and optimal design of intakes [12].…”

Chimney‐Like Intense Pelagic Upwelling in the Center of Basin‐Scale Cyclonic Gyres in Large Lake Geneva

“…Nearshore upwelling has been investigated in various lakes (e.g., Corman et al., 2010; Flood et al., 2020; Plattner et al., 2006; Pöschke et al., 2015; Reiss et al., 2020; Rowe et al., 2019; Valbuena et al., 2022). However, few studies have reported on dome‐ or bowl‐shaped thermoclines in lakes and pelagic upwelling/downwelling during summer (e.g., Beletsky et al., 2012).…”

Chimney-like intense pelagic upwelling in the center of basin-scale cyclonic gyres in large Lake Geneva

“…Nearshore upwelling has been investigated in various lakes (e.g., Corman et al, 2010;Flood et al, 2020;Plattner et al, 2006;Pöschke et al, 2015;Reiss et al, 2020;Rowe et al, 2019;Valbuena et al, 2022). However, few studies have reported on dome-or bowl-shaped thermoclines in lakes and pelagic upwelling/downwelling during summer (e.g., Beletsky et al, 2012).…”