3.3.1 Water Temperature, Stratification, and DO Concentrations
DO concentrations, water temperature, and Schmidt stability varied
considerably over the course of the Turnover Deployment (Figures 4A-C).
Prior to turnover, DO concentrations were strongly stratified by depth
and exhibited large sub-daily fluctuations in the epilimnion and
metalimnion (Figure 4C). Hypolimnetic DO concentrations were stable
around 2 mg/L during the pre-turnover period, due to the HOx system
operation (Figure 4C). A sharp temperature gradient (4-7°C) between the
epilimnion and hypolimnion existed until approximately 3 days prior to
turnover (Figure 4B). However, the water temperature profile equalized
periodically between the metalimnion and hypolimnion prior to turnover,
indicating ephemeral periods of mixing between those layers (Figure 4B).
Starting on 29 October 2020, the temperature gradient decreased
progressively until the full water column temperature profile equalized
on 02 November 2020, meeting our criteria for turnover.