Penetrative Convection Modifies the Dynamics of Downslope Gravity Currents

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 convection on aquatic gravity currents remain to be quantified. This paper demonstrates how the interaction between penetrative convection and downslope gravity currents impacts the fluid dynamics and transport across littoral aquatic systems. We performed field experiments in a wind-sheltered lake experiencing differential cooling to resolve the dynamics of thermally driven gravity currents in convective environments. Our in situ observations reveal that convective plumes penetrate gravity currents, generating large vertical fluctuations that foster the erosion of the stratified layer. This enhanced vertical mixing destroys the stratified downslope flow and limits the basin-scale transport. Our results demonstrate that the interaction between penetrative convection and downslope gravity currents controls the littoral-pelagic connectivity in aquatic ecosystems.

Automated summary

This research demonstrates the impact of the interaction between penetrative convection and downslope gravity currents on the fluid dynamics and transport in littoral aquatic systems. The study reveals that convective plumes can penetrate gravity currents, leading to large vertical fluctuations that enhance vertical mixing and erode the stratified flow, thus limiting basin-scale transport.