Publications by Ulrich Lemmin | EPFL Graph Search

Buoyancy-tilted Shear Layers and Coherent Structures in Hyperpycnal River Plume Plunging

David Andrew Barry, Ulrich Lemmin, Haoran Shi

Shear layers and corresponding Kelvin Helmholtz-type Coherent Structures (KHCS) can be generated by rivers discharging into laterally-unconfined quiescent open water bodies (e.g., lakes). When the river discharge has a greater density than the receiving wa ...

AMER GEOPHYSICAL UNION2025

Identifying and quantifying unexpected deep zooplankton diel vertical migration in a large deep lake

David Andrew Barry, Ulrich Lemmin, Htet Kyi Wynn, Rafael Sebastian Reiss, Valentin Kindschi, Violaine Florette Piton

Diel Vertical Migration (DVM), a widespread zooplankton behavior in freshwater and marine systems, affects ecological interactions and biogeochemical cycles. In lakes, DVM has mainly been studied in the upper 50 m of the water column. However, based on aco ...

American Society of Limnology and Oceanography2025

Hydro-sedimentary processes of a plunging hyperpycnal river plume revealed by synchronized remote imagery and gridded current measurements

David Andrew Barry, Ulrich Lemmin, Koen Blanckaert

The present knowledge of plunging hyperpycnal river plumes is mainly based on two-dimensional (confined) laboratory experiments. Several hypotheses on three-dimensional (unconfined) flow processes have been made, but not tested in situ. In this field study ...

American Geophysical Union2024

Field Observations Reveal How Plunging Mixing and Sediment Resuspension Affect the Pathway of a Dense River Inflow Into a Deep Stratified Lake

David Andrew Barry, Ulrich Lemmin

The pathway of dense river inflows into lakes, which affects the lake water quality, is not accurately predicted by existing models. The pathway of a dense riverine inflow in a lake with a submerged canyon is analyzed based on measurements during a 4-month ...

Amer Geophysical Union2024

Tracking the Nearfield Evolution of an Initially Shallow, Neutrally Buoyant Plane Jet Over a Sloping Bottom Boundary

David Andrew Barry, Ulrich Lemmin, Haoran Shi

Understanding coastal plane jets which occur when a body of water discharges into an ocean or a lake through a channel or outlet is important, since they play a significant role in sediment, nutrient, and pollutant exchange. This study investigates the nea ...

Amer Geophysical Union2024

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

David Andrew Barry, Ulrich Lemmin, Naifu Peng, François Mettra, Rafael Sebastian Reiss

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 densit ...

Amer Geophysical Union2024

From Particles to Flocs: Revealing Where Flocculation Occurs in the Nearfield of a Negatively-Buoyant River Plume in a Large Lake (Lake Geneva)

David Andrew Barry, Ulrich Lemmin, Htet Kyi Wynn, Valentin Kindschi, Violaine Florette Piton

The dynamics of sediments entering lakes in river plumes is virtually unknown. This field study provides unprecedented evidence of the initiation and evolution of suspended sediment flocculation in the nearfield of the negatively-buoyant Rh & ocirc;ne Rive ...

Amer Geophysical Union2024

Strong bottom currents in large, deep Lake Geneva generated by higher vertical-mode Poincaré waves

David Andrew Barry, Ulrich Lemmin, Rafael Sebastian Reiss

Although internal seiches are ubiquitous in large, deep lakes, little is known about the effect of higher vertical-mode seiches on deepwater dynamics. Here, by combining entire summer season current and temperature observations and 3D numerical modeling, w ...

Springer Science and Business Media LLC2024

What role does stratification play during winter in wind-induced exchange between the multi-depth basins of a large lake (Lake Geneva)?

David Andrew Barry, Ulrich Lemmin, Rafael Sebastian Reiss

Detailed studies of wind-driven interbasin exchange in lakes, focusing on the underlying driving forces and how they are affected by stratification, are presently lacking. We therefore investigated how strati-fication modifies wind-induced exchange between ...

2023

The role of submesoscale filaments in restratification of the surface mixed layer and dissolved oxygen variability in large Lake Geneva: field evidence complemented by Lagrangian particle-tracking

David Andrew Barry, Ulrich Lemmin, Seyed Mahmood Hamze Ziabari, Rafael Sebastian Reiss, Mehrshad Foroughan

Theoretical studies on oceans and large lakes have shown that submesoscale instabilities in frontal zones tend to reduce horizontal density gradients and enhance vertical density gradients, thereby re-stratifying the Surface Mixed Layer (SML). Submesoscale ...

2023