Arctic expedition unravels mysteries of the Northern Lights

Space physicists at the University of Southampton are probing the scientific mysteries of the Northern Lights in an expedition to a radar site deep in the Arctic Circle.

Researchers from Southampton Aurora Quest are making dozens of hours of observations this week while calibrating and upgrading instrumentation at the EISCAT Svalbard Radar.

The readings from the Svalbard island chain will support three inter-linked research projects, involving partners from University College London and Lancaster University, which will help scientists understand the heating of the neutral upper atmosphere by auroral processes.

Astronomy Outreach Leader Dr Sadie Jones is documenting the expedition in a daily blog and has hosted live link ups with Southampton schools to inspire pupils with the scientific discoveries. Images and 360 degree films taken during the expedition will also be used in an online competition for 14 to 18-year-olds this summer called the SETI Cipher Challenge.

The Aurora Borealis produce their colourful display when energised particles from space hit the Earth's atmosphere at around 40 million mph. These aurora typically deposit 50GW of power into the atmosphere, a sum comparable to the electricity consumption of the UK.

Intense current flows within and around the aurora affect the chemistry and climate of the upper atmosphere, however many fundamental aspects of these processes remain unanswered by modern science. The auroral heights remain too high for weather balloons, but too low for spacecraft.

One new solution being explored by Southampton's Dr Daniel Whiter is to calculate upper atmosphere's temperature by observing the ratio and brightness of two auroral colours.

‚"We are using extremely sensitive cameras equipped with colour filters to make maps of atmospheric temperature, just like a thermal imaging camera, he explains. "These temperature maps can be combined with radar measurements of the upper atmosphere to estimate the electrical conductivity, which is an important property influencing the flow of electric current through near-Earth space and the atmosphere."

Greater understanding of heating of the upper atmosphere will help improve atmospheric modelling and the prediction of drag on spacecraft in ultra-low orbits.

The current expedition in the Space Environment Physics research group is focussed on the Auroral Structure and Kinetics camera (ASK) stationed at EISCAT Svalbard Radar. The University instrument, which has been funded by the Natural Environment Research Council, is operated in conjunction with the Royal Institute of Technology (KTH), Stockholm.

Daniel is installing a new filter on one of the three ASK cameras to allow the imaging of temperature at around a 110km altitude. PhD student David Price is recording measurements of atmospheric temperature in and around aurora between 80km and 180km in altitude. Thirdly, the Southampton, UCL and Lancaster collaboration is measuring electric fields in the ionosphere on different scales to evaluate how important it is to observe at the highest possible resolution.