22 March 2016
Professor Mike Kosch, a leading space scientist in Lancaster’s Physics Department, has recently completed an expedition to the South Pole to carry out research into the interaction of thermospheric winds and temperatures with the auroras.

The sun emits approximately a million tons of radiation in terms of high energy particles every second, not including solar flares and coronal mass ejections, and this radiation is a major driver of space weather. The thermosphere is the interface region in the upper-atmosphere between space weather and terrestrial weather, protecting us from the high levels of radiation from outer space.

Professor Kosch had this to say of his journey:

“The South Pole, with its high altitude, clean air and location relative to the magnetic pole, is an ideal location to study the auroras and the Earth's atmosphere. Past explorers struggled and perished to reach this place only a century ago, pioneering the opportunity to do the cutting-edge research we do there today. It was a life's dream and privilege to visit and work at the iconic location of the South Geographic Pole."

After travelling to the US-owned McMurdo and Amundsen-Scott Antarctic stations (the latter being named for the early 20th century explorers), Professor Kosch helped deploy two Scanning Doppler Imagers (SDI), one at each location. These highly advanced pieces of night-vision optical equipment remotely observe the thermospheric neutral temperature and winds at altitudes of 100 to 300km, allowing meso-scale physics of the upper neutral atmosphere to be performed for the first time. The SDI is a novel fisheye version of the more conventional Fabry-Perot interferometer (FPI) that images the Doppler shift of the whole sky. Only seven of these instruments exist in the world, and each cost around £500,000. Traditional FPIs make one observation of the average temperature and wind over the entire sky (over a radius of about 300 km) about every 15-30 minutes. The SDI makes simultaneous observations of the entire sky with 20-50 km resolution about every 1-5 minutes, so the spatial and temporal resolution is much higher. This allows Professor Kosch and his collaborators to observe small-scale structures in the thermosphere.

Although most of the work was fortunately done indoors, the deployment team had to endure outdoor summer temperatures of as low as -31°C, with wind chills down to -46°C at the South Pole. The team travelled in and out of Antarctica by Hercules LC-130 military transporter, courtesy of the USA Air Force, starting from Christchurch, New Zealand.

Previous observations from Mawson, Antarctica, were a great success, with Professor Kosch proving that auroras can dramatically affect the direction and strength of the winds in the thermosphere. This was an unexpected result, as most scientists treat the thermosphere as a large, slow moving background gas. He also showed, through simultaneous observations from Antarctica and the Arctic, that the thermospheric winds in both hemispheres are the same, meaning that they are connected inter-hemispherically via the Earth's magnetic field. Both of these pieces of research were carried out for the first time, and subsequently published. New discoveries are expected from the newly deployed SDIs.