A new research radar based in Antarctica is giving scientists the chance to study the highest layer of the earth’s atmosphere at the very edge of space.

A new research radar based in Antarctica
is giving scientists the chance to study the highest layer of the earth’s
atmosphere at the very edge of space.



Dr. Pete Younger installing the new radar. (Image courtesy
of University of Bath)

Using the new radar, scientists will be able to investigate
climate change and explore the theory that while the lower atmosphere is
warming, the upper atmosphere is cooling by as much as 1 degree centigrade
each year.

They will also be able to find out more about the complex
waves, tides and other mechanisms that link this region – known as the mesosphere
– to the lower regions of the atmosphere.

At heights of around 80-100km (50-62 miles) the mesosphere
is notoriously difficult to investigate and is the least-explored part of
the earth’s atmosphere.

The low air pressure at this altitude means that it is
impossible to fly aircraft in the mesosphere and even the huge weather balloons
that are used to measure stratospheric ozone cannot climb high enough to
reach this altitude.

Satellites begin to burn up when they enter the mesosphere,
so the new radar – just installed at the Rothera research base in Antarctica
in a joint project between the University of Bath and the British Antarctic
Survey (BAS) – will help scientists explore the region using remote sensing.

“Fortunately, nature provides us with an excellent answer
to the problem of investigating the mesosphere,” said Professor Nick Mitchell
who heads the project in the Department of Electronic and Electrical Engineering
at the University of Bath.

“Meteors, or ‘shooting stars’, burn up in the mesosphere.
The meteors drift just like weather balloons so we can use a radar on the
Earth and bounce radio waves off the meteors to find how fast they are moving
and so measure the winds at the edge of space.

“The fading of the radio echoes from the meteors also
lets us measure the temperature of the atmosphere. We can detect thousands
of meteors in any one day and with this information study the waves and tides
that flow around the planet on a continuous basis.

“The mesosphere has been called the miner’s canary for
climate change; meaning that it is very sensitive and the changes there
may be larger than in any other part of the atmosphere.

“Evidence of these changes comes from sightings of noctilucent
clouds, very unusual clouds seen only in polar regions and known to be in
the mesosphere. These clouds don’t seem to have been observed before 1885
and may mark the onset of a long-term cooling of the upper atmosphere”.

The researchers hope to use this temperature data to see
if the effects of climate change are present in the upper atmosphere.

The radar is the latest element in a global array of radars
being installed by the University of Bath group. It will be used in tandem
with an identical radar at Kiruna, inside the Arctic Circle in Northern Sweden,
to find out if there are any differences between the Arctic and Antarctic
upper atmosphere.

“We know that there are big differences lower down in
the atmosphere, for instance in the stratosphere the ozone hole is much larger
over the Antarctic than over the Arctic, but we don’t really know what the
differences are like higher up,” said Professor Mitchell.

First results from the radar show that it is detecting
about 5,000 meteors ever day. Analysis at the University of Bath has revealed
frigid temperatures in the mesosphere, the lowest temperatures of about -130ºC,
paradoxically occurring at midsummer.

The Rothera radar has been installed by Dr Peter Younger,
a postdoctoral researcher from the University assisted by colleagues from
BAS.

The radar is made of six antennas about 2 metres high
set up over a space the size of a football pitch. The site itself is a rocky
beach on the edge of Marguerite Bay – a landscape of icebergs, penguins
and seals. Dr Younger has just returned to the UK having spent two months
on the installation.

Source : www.sciencedaily.com