International Dawn Chorus Day

As nature lovers all over the world wake up to enjoy the enthusiastic sounds of birdsongs on International Dawn Chorus Day on 2 May, scientists at British Antarctic Survey's (BAS) Halley Research Station will listen to a very different Dawn Chorus.

Each morning, as the Earth and its enveloping atmosphere turn towards the Sun, very low frequency radio waves produced in space, travel down to the ground where they can be "heard" using a simple radio receiver. When converted to audible sound waves, they are remarkably like birdsong and for this reason were named "Dawn Chorus" when they were discovered in the mid 20th century.

But there is more to this phenomenon than enchanting sounds. Dr Andy Smith and colleagues at BAS believe that 'chorus waves' are the accelerating power behind so-called 'killer electrons' that damage communications satellites during space storms. Massive eruptions on the Sun, known as Coronal Mass Ejections (CMEs) cause the solar wind to blow harder than usual, which accelerates these electrons to very high speeds.

Deep within the Earth's protective magnetic field lies the van Allen radiation belt - a region of charged particles in space that surrounds the Earth like a doughnut. Scientific opinion is divided on exactly how the so-called "killer electrons" penetrate the belt.

Scientists at Halley Research Station record chorus waves in an attempt to understand space weather processes. The ability to anticipate magnetic storms could help insurance, telecommunications and aerospace industries to better protect spacecraft costing upwards of 200 million US dollars.

A recent theory by BAS scientists and colleagues, based on measurements in space and Antarctica, has proposed that chorus waves generated by the solar wind interact with and accelerate the electrons. Andy Smith says "by understanding this process we are better informed on how to minimize disruption to satellites".