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Sounding out the Antarctic

This blog post was written by Grace Atkinson, a local student who came to see us in the Museum and asked if there was anything she could do. We gave her a research project, and this blog post is the outcome.

As an International Baccalaureate student with a keen interest in both geography and the Antarctic I decided to contact the Polar Museum to see if there was a project I could do outside of my studies to enhance my geographical knowledge as I am planning to study Geography at University. After looking at the exhibits I thought a blog post about radio-echo sounding in the Antarctic would be an engaging topic to research.

My aim is to increase people’s awareness of the different techniques used by scientists in the Antarctic to collect data from the ice sheets as the study of ice is becoming increasingly important; its thickness is useful in determining the impacts of climate change. Radio-echo sounding is a geophysical technique which investigates the thickness of glaciers and ice sheets, this becoming crucial within the study of glaciology. Before radio echo sounding was invented by the Scott Polar Research Institute in the 1960s, scientists such as Amory Waite, used radio to measure ice thickness however this method wasn’t widely known. Radar became more popular after an incident involving a WW11 Allied aircraft which when flying across Greenland crashed into the ice due to miscalculations with their radar altimeters. The accident caused increased interest in using the radar for experiments that measure ice sheet thickness in the Arctic.

Oliver Shepard stands on snow holding ice core drill during the Transglobe Expedition 1979-82.

There are lots of ways to study ice. In this picture Oliver Shepard stands on snow holding ice core drill during the Transglobe Expedition 1979-82.

The technique of radio-echo sounding since being developed in the 1960s is now used by a variety of institutes such as the US National Science Foundation to investigate and map the ice covered terrain in the Antarctic. As water and ice are transparent, low frequency electro magnetic waves can be used in the Antarctic to obtain the information and this method is accurate which is why it is used in other scientific investigations, for example marine acoustic sounding. There are echo pulses which penetrate the ice sheets enabling scientists to receive and analyse the data. These pulses are particularly useful for researchers studying the dynamics of ice sheets and their internal ice structure in sub-glacial regions. The radio echo sounding machine has two crucial components, these being the transmitter which sends out the echo pulses, and the receiver which records the strength of waves and the time it takes for waves to bounce back.

Traditional measurements of sea ice thickness are through drill holes which are effective at giving a good overview of ice thickness in extensive areas, however, the use of electromagnetism in radio echo sounding is much more accurate and reliable by comparison. In addition to this, one of the biggest advantages of radio echo sounding in the drilling of holes is its speed.

The invention of radio echo sounding has been influential and the gateway to the development of more recent methods of measuring sea ice thickness, for example the satellite altimetry which relies on the use of a radar pulse. However, there are limitations to the measurements as the laser only collects data in cloud-free conditions.

After researching the use of radio echo sounding in the Antarctic regions I believe it has proven to be the technology of major interest and importance due to its significance in scientific development such as the discovery of subglacial lakes in Antarctica.

Read about some of the work carried out by scientists at SPRI in recent years here.

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