Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms

A calibrated three-dimensional numerical model (Delft3D) and in-situ observations are used to study the relation between deep-water temperature deep mixing in Lake Garda (Italy). model-observation comparison indicates that is able adequately capture turbulent kinetic energy production surface layer its vertical propagation during unstratified conditions. From modeling results several processes identified affect Garda. The first process thermocline tilting due strong persistent winds, leading a temporary disappearance of stratification followed by mixing. second cooling, which acts when gradients nearly absent over whole depth arises as combination buoyancy-induced turbulence cooling winds. third differential causes cold water move from shallow parts lake deeper along sloping bottom. Two these (thermocline cooling) cause deep-mixing events, while deep-cooling events mainly caused cooling. Detailed quantities temperature, available at deepest point for year 2018, indicate was responsible location. Long-term simulations appear be very sensitive applied wind forcing. This sensitivity one main challenges making projections future occurrences episodic under climate change.