The Mysterious Ice Rings Of Lake Baikal

EnolaGaia

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Kids - check the satellite photos for ice rings before taking the shortcut and driving across Lake Baikal ...

These ice rings are generally circular rings of thinner / weaker ice within an otherwise hard-frozen lake surface. An ice ring is like a doughnut of thin ice both contained within, and containing, thicker / stronger ice. These aren't the same phenomenon as ice circles found in rivers and ponds, though I suppose an ice circle might result if an ice ring full melts away, leaving its center of thicker ice.

They were once thought to be unique to Lake Bailkal, but they've now been identified in two other Asian lakes.

They're often large enough to be clearly seen in satellite photos. Scientists have been trying to establish their cause for a long time.
What's causing mysterious 'ice rings' to form in the world's deepest lake?

The humongous, mysterious "ice rings" that pockmark the world's deepest lake during Siberia's winter and spring months may look like icy crop circles, but they're not due to alien activity, atmospheric conditions or even, as previously thought, methane bubbles percolating from the lake's bottom.

Rather, it appears that warm, swirling eddies of water under Lake Baikal's thick ice are responsible for these ice rings, some of which are up to 4 miles (7 kilometers) in diameter and can be seen from space, a new study finds.

Solving this mystery, however, wasn't an easy affair. An international team of researchers from France, Russia and Mongolia, who have studied the lake's ice rings since 2010, elected to travel to the lake biannually in 2016 and 2017 for a new study in which they drilled holes in the ice near the rings, and dropped sensors into the water below. One year, they heard that two vans had gotten stuck in the ice rings. One of them sank into the lake, and was never recovered. ...

In Siberia's colder months, Lake Baikal — the largest freshwater lake in the world, by volume — freezes over. The ice is so thick, people routinely drive over it, said study lead researcher Alexei Kouraev, an assistant professor at the Laboratory for Studies in Spatial Geophysics and Oceanography (LEGOS) at the Federal University in Toulouse, France.

"It's a no-brainer," Kouraev told Live Science. "It's a very long lake, and if you want to go from one side to another, either you do 400 kilometers [248 miles] one way and then 400 kilometers on the other coast." But the trip across the ice is just about 25 miles (40 km), "so the choice is evident," he said.

However, while the ice is thick outside of and inside these rings of thin ice, the rings themselves can put vehicles and their occupants at risk, Kouraev said. ...

Ice rings have formed on Lake Baikal since at least 1969, and can last anywhere from days to months, satellite images show. However, these rings have unpredictable behavior, and show up in different parts of the lake from year to year. Moreover, they tend to appear in late April, but can crop up as early as January or as late as May, Kouraev said.

But scientists couldn't figure out how they formed. One of the more popular theories, indeed one that Live Science reported on in 2009, suggested that the greenhouse gas methane bubbles up from the lake's deep bottom to cause these rings. But Kouraev and his colleagues noticed that some of these ice rings formed in the lake's shallower waters, areas with no known gas emissions.

After analyzing data from the sensors they had dropped into the lake, the scientists found that the lake had warm eddies flowing clockwise under its ice cover. The currents weren't as strong at the center of the eddies, which explained why the centers of these rings still had thick ice, Kouraev said. However, the current at the edge of the eddies was strong, which explained why the ice on top of this edge was thinner, he said.

The sensors revealed that the water at these eddies was 2 to 4 degrees Fahrenheit (1 to 2 degrees Celsius) warmer than the surrounding water. What's more, the eddies had a lens-like shape, a phenomenon that is common in oceans but rare in lakes. ...

But why did these eddies form in the first place? According to the sensors, which were kept underwater for 1.5 months at a time, as well as thermal-infrared satellite imagery, it appeared that the eddies formed each fall, before the lake froze over. Moreover, strong winds blowing in waters from the nearby Barguzin Bay could help them form, Kouraev said.

He noted that, so far, these ice rings have only been found in Lake Baikal, as well as the nearby Lake Hovsgol in Mongolia and Lake Teletskoye, also in Russia.

As for drivers who cross the frozen lake in their vehicles, Kouraev said that while cracks are easy to spot, the rings themselves can be harder to see at ground level because they're covered with ice. As a public service, Kouraev and his colleagues, who jokingly call themselves the Fellowship of the Ice Rings, have written booklets, given presentations and told Russia's national park service and ministry of emergencies about the rings. They also routinely update their website about the location of newly formed ice rings, which are visible in satellite images. ...

The study was published online in the journal Limnology and Oceanography in October 2019.
FULL STORY (With Photos): https://www.livescience.com/ice-rings-lake-baikal.html
 

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Here are the bibliographic particulars and abstract of the published research report. The full report is accessible (with illustrations) at the link.

Giant ice rings on lakes and field observations of lens‐like eddies in the Middle Baikal (2016–2017)

Alexei V. Kouraev, Elena A. Zakharova, Frédérique Rémy, Andrey G. Kostianoy, Mikhail N. Shimaraev, Nicholas M. J. Hall, Roman E. Zdorovennov , Andrey Ya Suknev
First published: 17 October 2019
Limnology and Oceanography
https://doi.org/10.1002/lno.11338

Abstract

Giant ice rings (diameter 5–7 km) detected on lakes Baikal (Russia) and Hovsgol (Mongolia) are a surface manifestation of intrathermocline lens‐like eddies under ice cover. By analyzing satellite imagery, we have detected new ice rings in 2016 and very old ones in 1969 for Lake Baikal. We have also discovered a giant ice ring on a new water body—Lake Teletskoye in the Altai Republic (Russia). Our recent field observations in the Middle Baikal have high temporal and spatial resolution and coverage and include temperature and current measurements over a long (1.5 month) period. In 2016, an eddy was detected in February and then an eddy and ice ring were detected in March at the same location. In 2017, another eddy was detected in February. This eddy was not stationary, as it was detected 6 km from its initial position in March, and thus no ice ring formed. The results of our field observations provide new data on the size and shape of the eddies. Indirect and direct measurements of currents and temporal evolution of the temperature field make it possible to estimate the rotation period (3 d) for the eddy in 2016 and assess the timing of movement, position, and displacement speed of the eddy in 2017. Thermal infrared Landsat imagery before ice formation in November–December 2015 shows that the eddy in 2016 was formed by the wind‐induced outflow from the Barguzin bay.

SOURCE / FULL ARTICLE: https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lno.11338
 

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A rotation in the water that did not turn into a whirlpool?
Yes, sorta ... The latest conclusion is that the rings represent weaker / thinner ice formed above relatively faint eddies of warmer water as the lake freezes. It was previously theorized that the rings resulted from emissions of gas coming up from the lake bed, but further tests revealed the rings formed in places where there were no lake bed gas emissions.
 

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It's interesting that they have only appeared since 1969. Or should I say noticed? Would that have anything to do with satellites being used to view the earth? I don't know how long satellites have been in use.
 

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So... do they reappear in the same places?
 

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So... do they reappear in the same places?
As I understand it - no, not always ...

The earlier lake bed gas emission theory was based on a presumption the ice rings always appeared in the same locations around the lake.

More detailed observations / surveys (quite possibly the ones in 2016 / 2017) demonstrated this wasn't true. This discovery was an important motivation for subsequently testing water temperatures beneath the ice rings to find out what was really common to all the sites.
 

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It's interesting that they have only appeared since 1969. Or should I say noticed? Would that have anything to do with satellites being used to view the earth? I don't know how long satellites have been in use.
The article says they've been known to form on Lake Baikal "since at least 1969." I take this to mean they weren't noticed as a regular phenomenon until the late Sixties.

I would guess they may have been observed by overflying aircraft and / or military reconnaissance satellites as early as the Sixties, or perhaps even earlier. It wouldn't be until the early 1970s that the earliest high-resolution earth observation program (LANDSAT) began. Prior to that satellites were usually imaging weather patterns rather than ground details.
 

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I am somewhat disappointed that we no longer think they are fairy rings.
 

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Something else occurred to me about the ice rings. They were originally believed to be unique to Lake Baikal. As the quoted article notes, they've now been identified in 2 other lakes.

One of Lake Baikal's famous features is its notably clear water, and this causes the resultant relatively clear ice covering it in winter. I wonder whether the clarity of Baikal's water and ice make the rings of thinner ice more obvious / visible than is the case on other similar bodies of water, and this is why they were thought to be Baikal-specific.
 
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