Publications by Hugo Nicolás Ulloa Sánchez

Lake surface cooling drives littoral-pelagic exchange of dissolved gases

Alfred Johny Wüest, Damien Bouffard, Tomy Doda, Hugo Nicolás Ulloa Sánchez, Cintia Luz Ramon Casanas

The extent of littoral influence on lake gas dynamics remains debated in the aquatic science community due to the lack of direct quantification of lateral gas transport. The prevalent assumption of diffusive horizontal transport in gas budgets fails to exp ...

Amer Assoc Advancement Science2024

Near-bed stratification controls bottom hypoxia in ice-covered alpine lakes

Damien Bouffard, Pascal Perolo, Tomy Doda, Nicolas Thomas Georges Escoffier, Janine Rüegg, Hannah Elisa Chmiel, Hugo Nicolás Ulloa Sánchez, Camille Roland Marie Minaudo

In ice-covered lakes, near-bottom oxygen concentration decreases for most of the wintertime, sometimes down to the point that bottom waters become hypoxic. Studies insofar have reached divergent conclusions on whether climate change limits or reinforces th ...

American Society of Limnology and Oceanography2023

Penetrative Convection Modifies the Dynamics of Downslope Gravity Currents

Alfred Johny Wüest, Tomy Doda, Hugo Nicolás Ulloa Sánchez

Gravity currents contribute to the transport of heat and mass in atmospheric and aquatic environments. In aquatic systems subject to daily surface cooling, gravity currents propagate through turbulent convective surroundings. Yet, the effects of thermal co ...

AMER GEOPHYSICAL UNION2023

Disentangling the effects of climate change and reoligotrophication on primary production in a large lake

Alfred Johny Wüest, Emile Barbe, Hugo Nicolás Ulloa Sánchez, Shubham Krishna

Climate change and reduction in nutrient loads have significant effects on primary production and phytoplankton growth dynamics. Since in the last few decades in many regions, nutrients in lakes were reduced simultaneously as the climate changed. Yet, it r ...

SPRINGER BASEL AG2023

Convective regimes induced by surface cooling and topography in stratified waterbodies

Damien Bouffard, Tomy Doda, Hugo Nicolás Ulloa Sánchez, Cintia Luz Ramon Casanas

Gravitational convection plays a significant role in the ventilation, heat and mass distribution of aquatic systems. This study investigates thermally driven convection resulting from heat loss at the air-water interface during cooling periods in freshwate ...

Iahr-Int Assoc Hydro-Environment Engineering Research2022

Seasonality of density currents induced by differential cooling

Alfred Johny Wüest, Damien Bouffard, Tomy Doda, Hugo Nicolás Ulloa Sánchez

When lakes experience surface cooling, the shallow littoral region cools faster than the deep pelagic waters. The lateral density gradient resulting from this differential cooling can trigger a cold downslope density current that intrudes at the base of th ...

2022

Flushing the Lake Littoral Region: The Interaction of Differential Cooling and Mild Winds

Damien Bouffard, Tomy Doda, Hugo Nicolás Ulloa Sánchez, Cintia Luz Ramon Casanas

The interaction of a uniform cooling rate at the lake surface with sloping bathymetry efficiently drives cross-shore water exchanges between the shallow littoral and deep interior regions. The faster cooling rate of the shallows results in the formation of ...

AMER GEOPHYSICAL UNION2022

Seasonality modulates wind-driven mixing pathways in a large lake

Alfred Johny Wüest, Bieito Fernandez Castro, Oscar Rodrigo Sepúlveda Steiner, Hugo Nicolás Ulloa Sánchez, Sebastiano Piccolroaz

Turbulent mixing controls the vertical transfer of heat, gases and nutrients in stratified water bodies, shaping their response to environmental forcing. Nevertheless, due to technical limitations, the redistribution of wind-derived energy fuelling turbule ...

SPRINGERNATURE2021

Development of overturning circulation in sloping waterbodies due to surface cooling

Alfred Johny Wüest, Damien Bouffard, Tomy Doda, Hugo Nicolás Ulloa Sánchez, Cintia Luz Ramon Casanas

Cooling the surface of freshwater bodies, whose temperatures are above the temperature of maximum density, can generate differential cooling between shallow and deep regions. When surface cooling occurs over a long enough period, the thermally induced cros ...

Cambridge University Press2021

Energetics and mixing of thermally driven flows in Hele-Shaw cells

Hugo Nicolás Ulloa Sánchez

Thermally driven flows in fractures play a key role in enhancing the heat transfer and fluid mixing across the Earth’s lithosphere. Yet the energy pathways in such confined environments have not been characterised. Building on Letelier et al. (J. Fluid Mec ...

Cambridge University Press2021

Horizontal transport under wind-induced resonance in stratified waterbodies

Alfred Johny Wüest, Serban George Constantinescu, Kyoung Sik Chang, Hugo Nicolás Ulloa Sánchez

Periodic winds acting on a stratified waterbody can amplify normal modes of motion and enhance the basin-scale circulation via resonance. Here, we use idealized largeeddy simulations to investigate the flow features and quantify the horizontal transport in ...

2020

Model-based data analysis of the effect of winter mixing on primary production in a lake under reoligotrophication

Alfred Johny Wüest, Hugo Nicolás Ulloa Sánchez, Shubham Krishna, Camille Roland Marie Minaudo

Nutrient loading, in combination with climate change are important drivers of primary productivity in lakes. Understanding and forecasting future changes in primary production (PP) in response to local and global forcing are major challenges for developing ...

ELSEVIER2020

Differential Heating Drives Downslope Flows that Accelerate Mixed-LayerWarming in Ice-Covered Waters

Alfred Johny Wüest, Damien Bouffard, Hugo Nicolás Ulloa Sánchez, Kraig Bates Winters

In ice-covered lakes, penetrative radiation warms fluid beneath a diffusive boundary layer, thereby increasing its density and providing energy for convection in a diurnally active, deepening mixed layer. Shallow regions are differentially heated to warmer ...

2019

Energetics of Radiatively Heated Ice-Covered Lakes

Alfred Johny Wüest, Damien Bouffard, Hugo Nicolás Ulloa Sánchez, Kraig Bates Winters

We derive the mechanical energy budget for shallow, ice-covered lakes energized by penetrative solar radiation. Radiation increases the available and background components of the potential energy at different rates. Available potential energy drives under- ...

2019

Mechanical energy budget and mixing efficiency for a radiatively heated ice-covered waterbody

Alfred Johny Wüest, Damien Bouffard, Hugo Nicolás Ulloa Sánchez

Ice-covered waterbodies are far from being quiescent systems. In this paper, we investigate ice-covered freshwater basins heated by solar radiation that penetrates across waters with temperatures below or near the temperature of maximum density. In this sc ...

Cambridge University Press2018

Hydrodynamics of a periodically wind‑forced small and narrow stratified basin: a large‑eddy simulation experiment

Alfred Johny Wüest, Damien Bouffard, Oscar Rodrigo Sepúlveda Steiner, Serban George Constantinescu, Kyoung Sik Chang, Hugo Nicolás Ulloa Sánchez

We report novel results of a numerical experiment designed for examining the basin-scale hydrodynamics that control the mass, momentum, and energy distribution in a daily wind-forced, small thermally-stratified basin. For this purpose, the 3-D Boussinesq e ...

2018

Temporal variability in thermally-driven cross-shore exchange: the role of semidiurnal tides

Hugo Nicolás Ulloa Sánchez

We examine temporal variability of thermally-driven baroclinic cross-shore exchange in the context of a tropical fringing reef system focusing on the role of tidally driven alongshore flow. Ensemble diurnal phase averaging of crossshore flow at the Kilo Na ...

2018