Using radar to study avalanches can provide valuable clues as to not just when they might occur, but how they will behave when they do. Current approaches, however, are unable to gauge all of movement deep inside these tumbling masses of snow and ice, but an advance in radar technology is promising to reveal a few more of their secrets. The new system pierces through the powder cloud to create 3D images of an avalanche's insides, helping to inform improved defenses against their devastating effects.
Dubbed the Advanced MIMO Radar Development for Geophysical Imaging Applications, the new system was developed by engineers at University College London (UCL), Durham University and Sheffield University. The team set out to build a modular phased array radar system that would improve our understanding of the flow dynamics inside an avalanche, in turn helping us better predict their behavior and plan for the fallout.
The system uses a transmit antenna and a 1.95 m (1.64 ft) receiver array to send and receive radio waves. The team says these bounce off the snow with just the right amount of power and at just the right wavelengths to maximize penetration of the powder cloud as it slides down the mountain.
The claimed benefit is where current methods offer crude images of flow speed averaged over 50 m (164 ft) to give an overall measure of velocity, the new system digs deeper. It reduces this averaging distance to just 1 m (3.3 ft), which for the first time, allows individual blocks in the flow to be imaged and assessed in relation to the dynamics of the overall avalanche.
The system was put to the test in the Swiss Alps last winter to produce 3D images of snow flowing deep inside avalanches. The team describe this trial as a success and say that the new data it has gathered can already be used to improve computer models to better understand avalanche activity.
"It's not possible to predict precisely when avalanches will happen, but our radar imaging system aids understanding of how they behave when they do occur," says Professor Paul Brennan from UCL and project lead. "By penetrating the powder cloud, it can observe the nature and direction of the flow of the 90 per cent of snow that would otherwise remain invisible."
The system, which requires proper installation and connection to a mains power supply, can also be put to work assessing other moving masses of debris, such the depletion of Antarctic ice shelves in the context of climate change and rising sea levels, and even volcanic eruptions. Brennan tells us that the system continues to watch over avalanches in the Swiss Alps, but that a version of it has been requested by the Austrian Research Centre for Forests and his team is currently building a related radar for volcano imaging.
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