Salt-Fingering in Seasonally Ice-Covered Lakes

When ice forms on lakes, dissolved salts are rejected, which can lead to under-ice salt finger formation. We performed a series of laboratory experiments to visualize these fingers. While we detected salt fingers in our camera recordings, the signal of these fingers is nearly absent in the temperature record. We quantify the velocity of the salt-plumes and measure the bottom salinity increase from these fingers. Further, we estimate that the salinity is often distributed evenly with depth. Comparing the salt fluxes in our experiments with a typical salt flux in lakes, we suggest that conditions are favorable for salt fingering in most seasonally ice-covered lakes.

Automated summary

This study visualizes the salt finger formation under ice in lakes through laboratory experiments, showing that while these fingers can be detected in camera recordings, they are nearly absent in temperature records. The research quantifies the velocity of salt-plumes, measures the increase in bottom salinity, and suggests that salinity is often distributed evenly with depth. By comparing salt fluxes, it is concluded that favorable conditions for salt fingering exist in most seasonally ice-covered lakes.