AntarcticDoctor

The recent winds did more than just topple weather records – today we discovered the wind had also flattened all but one of the towers which support the HF radar antenna.

SANAE IV’s HF radar (pictured in the photo above, taken last summer) is the largest of the scientific research installations at Vesleskarvet.  16 T-shaped towers stood 15m high in an east-west line more than 200m long, supporting a grid of aluminium antenna elements which collectively transmit and receive signals allowing scientists to study the upper atmosphere over the South Pole.  Our radar is part of a network of similar stations all around Antarctica  which contribute data to create three-dimensional images (eg. of the ionosphere over the Pole) which is then fed to collaborative groups of scientists around the world (the SHARE and SuperDARN projects).

The same hurricane-force winds which damaged my tent caused failure of one of the anchors of the radar, causing 15 of the 16 towers to fall like dominoes.  The damage is beyond our facilities and supplies to repair; a full-blown reconstruction will have to take place in summer.  Still, there is a silver lining:  reconstructing the radar allows changes and upgrades to the design to be implemented.  Antarctica might be the most challenging earth-bound location to conduct scientific investigation, but she is still an awesome laboratory and window on the universe.  Besides – if it were easy, it wouldn’t be fun.

SANAE HF Radar on Google Earth

We were very lucky today to spot not one but two rare atmospheric phenomena today – nacreous and noctilucent clouds. Nacreous clouds are found in the stratosphere 15-25km above the surface of the Earth, and are thus high above other ‘normal’ cloud types. They are usually only seen in polar regions when the sun is below the horizon but reflects off the high clouds. The colours are beautiful and shimmering, reminiscent of an aurora. In the photo above, the nacreous clouds are the faint blue pattern on the lower left side. (The white band on top right is the noctilucent cloud – see below).

Noctilucent (or polar mesospheric) clouds are so high they have been labelled as being ‘on the edge of space’, between 80 and 120km above the planet. They are typically blue or white and are seen to shine before dawn and after dusk – or in the polar night when the sun is 6-16° below the horizon. Their origin is an unsolved mystery, as theoretically there should be no ice or water at this level. One theory (by far my favourite) is that dust and ice is shed by small meteors as they enter the planet’s atmosphere… quite something to look at glowing clouds in the dark sky and think they are formed from extraterrestrial ice 🙂 The noctilucent clouds are easily visible in the photo above as a glowing white band.

To Download right click > save as => Aurora

Last night (well, to be fair, in the early hours of this morning) I spotted a pale auroral band over the southern horizon, and decided to put into practice the experiments I’ve been conducting with my camera. I set up a time-lapse exposure of the southern sky, and left it running for more than two hours, until the battery died in the cold. Fortunately, around 0200 there was a significant event and a beautiful aurora. While the pictures can’t capture the intensity and life of an aurora in its full glory, the video gives a taste of what it is like.

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For interests sake – the video consists of hundreds of 30 second photographic exposures played at 8 frames per second, so you are seeing time pass at a rate of 4 minutes/second, or 240x acceleration. I’ve included an example of the still images below: