'Catch a Falling Star - Using Meteors to Study the Winds, Waves and Tides at the Edge of Space'
Every day, about 40 tons of extra-terrestrial material collides with the Earth. This
material is mostly in the form of tiny particles originating from comets. At heights of
about 100 km, friction heats the particles so that they vaporise, giving rise to the
streak of light seen from the ground as a meteor or "shooting star". This meteor region
of the atmosphere is, in a very real way, the edge of space.
The meteor region is notoriously difficult to investigate, but hosts a wide range of
poorly-understood phenomena. Atmospheric tides and waves launched from below are
thought to drive its circulation, coupling together different layers of the atmosphere.
Smoke from meteors acts as condensation nuclei for ghostly, polar noctilucent clouds
and the meteor region is also home to the giant lightning discharges known as sprites.
Its great sensitivity has lead to its being called the miner's canary of climate change.
Professor Mitchell's research involves using sophisticated radars to detect meteors in
the atmosphere. The meteors are used as tracers of atmospheric motion and reveal the
intricate dynamics of the meteor region. An array of radars at sites ranging from the
Arctic to the Antarctic are being used to monitor and investigate this enigmatic part
of the atmosphere. The lecture will outline the challenges posed in remote-sensing
techniques by meteors and the meteor region, it will present some key recent results,
and will look towards future problems.