New radar on Falklands will probe southern lights
26 October 2010, by Tamera Jones
Scientists have installed a new radar station on the Falkland Islands to monitor the particles high up in our atmosphere that cause the southern lights. The station will let them scan a region of the southern hemisphere that sees more than its fair share of auroral activity.
It will also help researchers forecast the sort of space weather that can damage satellites, help them understand how particles from the Sun can affect our weather and show them where meteors have hit the upper atmosphere.
The station is made up of 16 fifty-foot aerials and joins a network of 22 similar radars in the northern and southern hemispheres. At the moment most of these stations are in the northern hemisphere – places like Iceland, Finland and Alaska. This is because there are more places on land where you can see the northern lights compared with the southern hemisphere.
'There's not much land in the southern hemisphere in the places where you can see aurora, so there are fewer places to build stations,' says one of the lead researchers, Dr Steve Milan from the University of Leicester.
When electrons and protons in the solar wind reach the Earth, our planet's magnetic field traps and energises some of them while focussing others towards the poles where they collide with atoms in the atmosphere. This is what creates the spectacular northern and southern lights.
'There's not much land in the southern hemisphere in the places where you can see aurora, so there are fewer places to build stations.'
Dr Steve Milan, University of Leicester
But the Earth's magnetic field isn't uniform and is weak in some places, stronger in others. The Falklands are in a region of the southern hemisphere where the Earth's magnetic field is fairly weak, called the South Atlantic Anomaly.
'Plasma-charged particles find their way to the Earth by following magnetic field lines. Around the Falklands the magnetic field is weak, so particles penetrate deeper into the upper atmosphere,' explains Milan.
If satellites are in a low Earth orbit in this region, they're more likely to be affected by these particles. 'Normally the best auroral displays are the worst time for spacecraft,' says Milan. 'If a satellite's orbit has to go through the South Atlantic Anomaly, protection for it and its electronics needs to be beefed up.'
Although auroral monitoring is well established in the northern hemisphere, there aren't that many stations in the southern hemisphere. Now there's a big push to establish a ring of stations in the lower latitudes.
The Falkland Islands radar antenna array, comprising 16 50-foot masts.
'The only way you can keep track of what's going on high up in the atmosphere – in the ionosphere – is either by using spacecraft or by using radars,' says Milan.
Radars send out pulses of radio waves which hit charged particles in the ionosphere before returning to Earth. The amount of time it takes for these waves to come back tell researchers exactly how far away the charged particles are and how fast they're moving.
Radars are much cheaper to set up and run than spacecraft, and they can scan large parts of the sky. The British Antarctic Survey usually runs a radar station in Antarctica at its Halley Research Station.
But this new venture on the Falkland Islands uses electronics from the radar at Halley Research Station (which is in the middle of being moved and rebuilt) and aerials that belong to the University of Leicester.
'We and colleagues at BAS decided we could join forces to create a new radar system on the Falklands,' says Milan.
As well as monitoring auroral activity, the researchers hope that by investigating the South Atlantic region, they'll understand more about how particles in the solar wind affect our weather.
'It's been a controversial area,' admits Milan. 'But evidence is stacking up to suggest that these particles reach far down into our atmosphere and feed into our weather.'
The researchers set the station up in February this year, but it's taken until now to collect enough data to make sure it's working properly. It's planned to operate for two years.
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