Danger! May contain educational material

What would posses a Met observer to get out of bed at 5 am on a Saturday morning?  That’s a loaded question I know, but on this particular occasion it was due to a rather large balloon flying at 17 km above our heads!  No, we weren’t trying to shoot down Richard Branson; instead this balloon’s payload consisted of a vast array of scientific equipment that is part of an international cooperative effort to study the atmosphere above Antarctica.  These huge balloons were released from McMurdo Station earlier in the month and will spend up to the next 100 days circling the Antarctic continent transmitting from the stratosphere real-time data of winds, temperature, pressure, humidity, and particles and of particular concern to us, ozone.  As the balloon approached Davis the plan was for us to synchronise the fly over with the release of one of our own weekly ozone balloons (hence the early start).

The release of the long-duration stratospheric super-pressure balloon from McMurdo Station early in the month (Photo: McMurdo post).

So what is ozone, why is it so important and why are we still interested in it, wasn’t that so last century?  Well ozone is a special form of oxygen (with the chemical formula of O₃) that constitutes a very small part of our atmosphere, but its presence nonetheless is vital to human wellbeing.  Most ozone resides high up in the atmosphere, between 10 and 40 km above Earth's surface in a region called the stratosphere.  It is here that ozone does us a huge favour by absorbing some of the sun’s biologically harmful ultraviolet radiation.  In 1985 scientists from the British Antarctic Survey discovered that since the mid 1970s ozone values over the Antarctic had been steadily dropping when the sun reappeared each spring.  Something in the stratosphere was destroying ozone.

Satellite data of the ozone hole over Antarctica as of 20 September 2010.  Blue and purple depict areas of depleted ozone.  Latest ozone values from the stratosphere above Davis are 191 Dobson units (Image: NASA)

As we all know, chlorofluorocarbons (CFCs) that were released into the atmosphere by industrial activity were the culprit.  It was this discovery and its potential consequences to human health that prompted governments around the world to sign the Montreal Protocol, which ensured the swift phasing out of both the production and consumption of ozone depleting substances (ODSs).  The problem however, is that although the Protocol has been successful, ozone depletion will continue for many more decades because several key ODSs last a long time in the atmosphere after emissions end.

Enter climate change.  In the Antarctic, a projected increase in temperatures in the lower atmosphere (troposphere) will paradoxically result in decreased temperatures higher up in the stratosphere.  These lower temperatures would only exacerbate ozone destruction by increasing the frequency and extent of polar stratospheric clouds (PSCs).  These beautiful clouds only form at temperatures below -80°C and contain the chemical compound that is responsible for the catalytic destruction of ozone in the presence of sunlight.  Collaborative work between the Ice, Ocean, Atmosphere and Climate (IOAC) program of the AAD, the Bureau of Meteorology and other international organisations aim to further understand these complex interactions in a changing climate.

An image depicting the “Mother of Pearl” appearance that these high polar stratospheric clouds can exhibit.  As beautiful as they are, their chemistry helps to break down the ozone layer every spring (Photo: McMurdo post)

After the very ordinary weather we’d experience last week it made a nice change to get outside once more.  The fine conditions this week allowed both myself, Ben and Kim to head out on the sea ice and continue the fortnightly seawater sampling.

Kim and Ben drilling through the 1.5 metres of sea ice so that the seawater beneath could be sampled

Whilst we were out water sampling we were paid a visit by a very inquisitive Emperor penguin.  Whata you lookin at?  (Photo:  Ben O'Leary)

(Photo:  Ben O'Leary)