Modeling and observing the Lake Albano dynamics

Abstract. Lake Albano is a monomictic volcanic crater lake in Central Italy with CO₂-rich waters presenting CO₂ concentration varying over time. Depending on the period of the year, the lake is characterized by strong stratification or rather overturning events. In the warm season, the heating of the surface water results in a highly stratified vertical density profile, while in the cold season, the surface water cooling leads to a potential vertical instability of the water column. In this case, a partial/deep overturning of the lake water column may occur with the degassing in the atmosphere of the CO₂ which was accumulated as dissolved species in the deep water layers following seismically induced gas recharge, months to years before. Such a process has been periodically observed in Lake Albano in the past and could pose a potential hazard to the surrounding environment and population. A 3D numerical model is implemented to investigate the lake dynamics and the occurrence of overturning events. The model is validated and calibrated using both historical observations and measurements acquired during this study. These include temperature and salinity profiles from the deepest central portion of the lake, surface water temperature time series recorded by sensors installed on the lake shores, mounted on remotely operated vehicles, and on low-cost, innovative, self-powered drifting buoys. The latter have also been used to assess the modeled surface circulation of the lake.