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Aerial view of Ross ice floe in Antarctica. Scientists have discovered that one of the world's largest ice platforms produces a low buzz caused by the wind drumming on the snow-covered surface. The sound is almost continuous and changes pitch depending on the surface situation. ( American Geophysical Union (AGU) | Youtube )
The Antarctic sings. Scientists have discovered that one of the largest ice sheets in the world produces a series of almost continuous tones.
The phenomenon was observed by accident on Ross ice floes. Scientists who monitored the vibrations of the continent's largest ice shelf were "stunned" to discover the low buzz caused by the wind blowing on its snow-covered dunes.
A study on the seismic noise created by the Ross Ice Shelf has been published in the newspaper Letters of geophysical research of the American Union of Geophysics.
The singing ice tray
Unfortunately, the soft sound of the pack ice is too weak for the human ear to hear – the sound is recorded at a frequency above 5 Hz. To "listen" to the seismic tones of the Ross ice floe, scientists have buried sensitive sensors under the surface of the ice. An accelerated recording of the buzz has been published by the American Geophysical Union on its social media pages (see below).
"It's a bit like you're constantly blowing on the floe of a flute," explained geophysicist Julien Chaput, lead author of the study.
The low hum of Ross ice pack occurs when the wind blows over the snow-covered dunes, vibrating the surface and producing a seismic tone that only sensitive machines can detect. Scientists were on site to study the low frequency vibrations caused by earthquakes and ocean waves. However, on closer inspection, they discovered that the surface of the icecap vibrated constantly.
They also found that the buzz of pack ice changed with weather conditions. When there is a strong storm blowing on the surface of the pack ice and rearranging the layer of snow, the ice vibrates at different frequencies. The temperature of the air also influences the rate at which seismic waves cross the snow on the surface. Scientists are comparing the process to a musician who changes the pitch of a note on a flute by altering the speed of the airflow or selecting the hole in which the air comes out.
"Either you change the speed of the snow by heating it or cooling it, or you change direction, adding or destroying dunes," said Chaput. "And these are essentially the two forcing effects that we can observe."
Diagnose the Ross Sea Ice
The researchers hope that the changes to the seismic snoring of the pack ice could reveal new details on the pack ice, especially if it is likely to break.
The Ross ice floe is the largest ice sheet in Antarctica. It is about 487,000 square kilometers, about the size of Texas and France. It also plays an important role in the stabilization of the ice cap on the continent and acts as a "plug" preventing inner glaciers from melting into the ocean.
Due to global warming, ice sheets in Antarctica are becoming thinner. Some have retreated or even collapsed due to rising sea levels and warming temperatures.
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