Wind‐Induced Hypolimnetic Upwelling Between the Multi‐Depth Basins of Lake Geneva During Winter: An Overlooked Deepwater Renewal Mechanism?

Reiss, Rafael Sebastian; Lemmin, Ulrich; Barry, David Andrew

doi:10.1029/2021jc018023

Cited by 9 publications

(9 citation statements)

References 54 publications

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“…However, in the Pingzhai Reservoir, the surface T water exceeds 10 • C in autumn and winter, and the surface T water is still higher than the lower layer, so the density of the upper layer is lower than that of the lower layer. Therefore, in the Pingzhai Reservoir, the reflux gradient flow is the main mechanism of the water mixing in the upper and lower layers of the reservoir [53,54], and the gradual decrease in the pCO2 in the reservoir from the bottom to the surface layers (Figure 4) confirms the existence of this mechanism. Thus, the different sources of DIC influence whether DIC concentration stratification occurs in the reservoir.…”

Section: Source Influences the Vertical Difference In Dic Concentrationmentioning

confidence: 80%

Vertical Divergence Characteristics of Dissolved Inorganic Carbon and Influencing Factors in a Karst Deep-Water Reservoir, Southwest China

Zhou

Wang

et al. 2023

Atmosphere

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In deep karst reservoirs, the internal environment is complex, and thermal stratification isnot the only factor controlling the vertical distribution of the DIC concentration. Previous studies have not fully understood the migration and transformation of DIC in a deep-water reservoir. In this study, a deep-water reservoir in southwest China was chosen, and the spatial and temporal characteristics of the DIC concentration, pCO2, δ13CDIC value, and SIc were investigated. It was found that the Pingzhai Reservoir is a double temperature leapfrog reservoir. The DIC concentration, pCO2, Sic, and δ13CDICvalues showed annual cycle variation. During the thermal stratification phase, the DIC concentration, pCO2, Sic, and δ13CDICvalues were significantly different between the surface layer and the lower layer. However, during the mixing and mixed phases, the differences were not significant. The vertical divergence of the DIC in the Pingzhai Reservoir was influenced by the subtemperate layer, human activities, and sources. The formation of the subtemperate layer was due to the submerged flow formed when river water enteredthe reservoir, which provides a channel for DIC from the river to enter the lower layer of the reservoir. Human activities increased the solubility of carbonate rocks in the reservoir, and the source of DIC was one of the factors contributing to the concentration stratification of DIC in the reservoir.

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Section: Source Influences the Vertical Difference In Dic Concentrationmentioning

confidence: 80%

Vertical Divergence Characteristics of Dissolved Inorganic Carbon and Influencing Factors in a Karst Deep-Water Reservoir, Southwest China

Zhou

Wang

et al. 2023

Atmosphere

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“…(2022), and Reiss et al. (2020, 2022, 2023) showed that the model can accurately capture both submesoscale and basin/mesoscale processes in Lake Geneva. Realistic atmospheric fields (including wind, temperature, humidity, solar radiation), extracted from the COnsortium for Small‐scale MOdeling (COSMO) atmospheric model provided by MeteoSwiss with a resolution of 1 km (Voudouri et al., 2017), were used to force the lake surface.…”

Section: Methodsmentioning

confidence: 99%

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

et al. 2023

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Basin‐scale quasi‐geostrophic gyres are common features of large lakes subject to Coriolis force. Cyclonic gyres are often characterized by dome‐shaped thermoclines that form due to pelagic upwelling that takes place in their center. At present, the dynamics of pelagic upwelling within the surface mixed layer (SML) of large lakes are poorly documented. A unique combination of high‐resolution 3D numerical modeling, satellite imagery and field observations allowed confirming, for the first time in a lake, the existence of intense pelagic upwelling in the center of cyclonic gyres under strong shallow (summer) and weak deep (winter) stratified conditions/thermocline. Field observations in Lake Geneva revealed that surprisingly intense upwelling from the thermocline to the SML and even to the lake surface occurred as chimney‐like structures of cold water within the SML, as confirmed by Advanced Very High‐Resolution Radiometer data. Results of a calibrated 3D numerical model suggest that the classical Ekman pumping mechanism cannot explain such pelagic upwelling. Analysis of the contribution of various terms in the vertically averaged momentum equation showed that the nonlinear (advective) term dominates, resulting in heterogeneous divergent flows within cyclonic gyres. The combination of nonlinear heterogeneous divergent flow and 3D ageostrophic strain caused by gyre distortion is responsible for the chimney‐like upwelling in the SML. The potential impact of such pelagic upwelling on long‐term observations at a measurement station in the center of Lake Geneva suggests that caution should be exercised when relying on limited (in space and/or time) profile measurements for monitoring and quantifying processes in large lakes.

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“…(2004) was adopted to consider thermobaricity, with salinity kept constant at 0.05 psu since conductivity in Lake Geneva is small (see Text S2 in Supporting Information ). The present study is based on a model set‐up that was adapted for Lake Geneva (Cimatoribus et al., 2018) and extensively compared with field observations under a variety of conditions (Cimatoribus et al., 2018, 2019; Hamze‐Ziabari, Lemmin, et al., 2022; Hamze‐Ziabari, Razmi, et al, 2022; Reiss et al., 2020, 2022, 2023). It consistently gave good agreement.…”

Section: Methodsmentioning

confidence: 99%

“…These and similar observations led Lemmin (2020) to conclude that deepwater renewal in Lake Geneva is the result of complex 3D transport processes. Recently, Reiss et al (2020); Reiss et al (2022Reiss et al ( , 2023 investigated the contributions of wind-driven coastal upwelling processes and wind-driven interbasin exchange to deepwater renewal in Lake Geneva. It was demonstrated that water discharged from the Lake's shallow basin (Petit Lac) can penetrate down to ∼200-m depth into the hypolimnion of its deep basin (Grand Lac), again emphasizing the importance of 3D advective processes in deepwater renewal.…”

Section: Introductionmentioning

confidence: 99%

Deepwater Renewal in a Large, Deep Lake (Lake Geneva): Identifying and Quantifying Winter Cooling Processes Using Heat Budget Decomposition

Peng,

Lemmin,

Mettra

et al. 2024

Water Resources Research

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Wintertime deepwater renewal, which is important for heat–oxygen–nutrient exchange in lakes, is traditionally considered to be mainly driven by 1D vertical convective cooling. However, differential cooling between shallow and deep waters can produce density currents that flow into deep layers. In order to determine the role that these two cooling processes play in deepwater renewal, field measurements and 3D numerical modeling were combined to investigate heat content dynamics in Lake Geneva's large basin, the Grand Lac (maximum depth 309 m), during an exceptionally cold air spell in early 2012 where complete overturning had been reported. In a novel approach, the heat budget of the lake was decomposed, which allowed the identification and quantification of the heat budget components. The heat budget decomposition revealed that vertical convective cooling only penetrated to 200 m and that lateral advection was not only caused by density currents being discharged from the shallow littoral zone of the Grand Lac, but also from the Lake's shallow Petit Lac basin (maximum depth 75 m); the latter was found to be the main driver of heat content decrease in the deep layers of the Grand Lac below ∼200‐m depth. These findings provide unique insight into heat exchange processes that cannot be obtained from field data or numerical simulations alone. Heat budget decomposition proved to be a powerful, universally applicable tool for quantifying the contribution of alternative deepwater renewal processes. This is important, since deepwater renewal by convective cooling is weakening due to persistent global warming.

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Wind‐Induced Hypolimnetic Upwelling Between the Multi‐Depth Basins of Lake Geneva During Winter: An Overlooked Deepwater Renewal Mechanism?

Abstract: The exchange flow between distinct sub-basins and large embayments is a ubiquitous feature of many lakes, for example,

Cited by 9 publications

References 54 publications

Vertical Divergence Characteristics of Dissolved Inorganic Carbon and Influencing Factors in a Karst Deep-Water Reservoir, Southwest China

Vertical Divergence Characteristics of Dissolved Inorganic Carbon and Influencing Factors in a Karst Deep-Water Reservoir, Southwest China

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

Deepwater Renewal in a Large, Deep Lake (Lake Geneva): Identifying and Quantifying Winter Cooling Processes Using Heat Budget Decomposition

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