Siberia’s Lake Baikal holds a number of world records for lakes – oldest lake, deepest, largest freshwater lake by volume, and subjectively, the world’s clearest lake. Its remoteness and close proximity to China has given it many myths and legends – a dragon’s tail cracked the earth and its fire melted the snows to fill it; a dragon turned into a beautiful woman and became the mother of the local Buryat people; a dragon still lives in the lake. There are tales from both World War I and II of lost gold in the lake and many sightings of UFOs above it and alien encounters around it and even underwater. While those myths and legends remain unsolved, a more recent one involving giant ice circles visible only by air may have finally been solved. UFO ice-fishing platforms? Dragon skating rinks? Mysterious lost treasure indicators?
“To fully understand the evolution of water structure and dynamics, there is a need to have better temporal resolution and larger time span. Starting from 2016, we have changed our monitoring strategy—every winter we carry out not one, but two field surveys that take place in mid‐February and (as usual) in late March. During each survey we perform (1) surface measurements of ice thickness and snow depth, as well as ice structure and roughness, (2) vertical profiles of temperature and conductivity, and (3) direct and indirect estimation of current field. We also install temperature loggers and current meters that stay in place between the February and March.”
Ice ring on Lake Baikal
Lake Baikal’s giant ice rings were first seen in 1969 and have been studied ever since without an explanation being discovered. There have been no consistent sizes nor locations nor water depths for the formations. Visible from space, the massive ice circles lasted from days to months. From 2010 to 2017, Alexei Kouraev, an assistant professor at the Laboratory for Studies in Spatial Geophysics and Oceanography (LEGOS) at the Federal University in Toulouse, France, led a new expedition using different techniques to solve the dilemma. As he explains in the journal Limnology and Oceanography, the research team drilled though as much as 700 feet of solid ice to drop temperature recorders and flow detectors that were left in place for as long as 1.5 months. What they found was surprising.
“Our hydrographic surveys beneath the ice rings in Lake Baikal in 2012–2014 and in Lake Hovsgol in 2015 have shown the presence of warm lens‐like (double‐convex form) eddies before and during the manifestation of ice rings (Kouraev et al. 2016).”
Ah-ha! The sensors showed eddies flowing clockwise beneath the ice. The temperature sensors showed that these eddies were 2 to 4 degrees Fahrenheit (1 to 2 degrees Celsius) warmer than the surrounding water. That combination forms the giant ice circles.
“We have shown that giant ice rings are a surface manifestation of these intrathermocline lens‐like eddies. These eddies exist before and during the manifestation of the ice rings. They have an isolated circular form and radial symmetry, and their position corresponds to the location of ice rings.”
Ice rings (NASA image)
The lens-shaped eddies – a shape seen in oceans but not in lakes – actually formed in the fall before the lake froze over, possibly sent into motion by winds blowing from nearby Barguzin Bay. The researchers found current speed variations within the eddies – they were weak in the center and strong at the edges – which explains why the ice in the rings is thicker in the middle and thinner around the edge.
While the mystery of the ice rings appears to have been solved, the mystery of why people still try to drive on the ice – to sometimes disastrous results – has not.