If you've ever wandered up the western end of Casey station in the wee hours of the morning or gone for a post-degustation stroll up Reeve's Hill in the evening in search of the mythical Casey aurora, you may have seen some other flashing lights rising from the surface to quickly disappear into the near-permanent bank of clouds hovering above station.
Never fear though, they are not hostile spy-drones, alien spacecraft or mischievous ice sprites, merely harmless radiosondes attached to weather balloons, released by your friendly BOM staff twice a day at 1115UTC and 2315UTC. Radiosondes are released from all around the world as part of the World Meteorological Organisation's (WMO's) upper air program which sees weather balloons released from more than 1300 sites worldwide, collecting data from the troposphere and lower stratosphere that goes into building and verifying weather prediction models and becomes part of the climate record.
As is often the case with repetitive jobs performed by a small team on a regular basis, some healthy competitive rivalry has emerged. While not enjoying any of the fanfare or media exposure of France 2024, the Casey balloon Olympics is still a hard-fought competition with multiple events to challenge the teams:
Precision - aiming to hit the optimum speed of ascent of 5m/s between launch and 100hPa, competitors spend hours crunching the numbers on hydrogen gas volumes, winds speeds, pressure and weather conditions to try to hit that elusive ascent rate that allows for synchronisation with the hundreds of other balloon releasing sites around the world.
Endurance - concocting secret blends of volatile organic cocktails designed to improve balloon elasticity and deflect ice crystals to maximise termination height.
Resilience - just diving head-first into the elements, attempting successful release of balloons at high wind speeds, holding on for dear life and hoping not to get clipped in the head by a rogue sonde.
Seriously though, the data collected by radiosondes around the world is scientifically important, telling meteorologists around the world what is going on in the atmosphere far above us so they can use that information to develop accurate weather predicting models, even more so in Antarctica where much of the weather of the Southern hemisphere is formed.
As a team, we are committed to launching balloons twice daily regardless of the weather and with no upper limit to the speed at which we can attempt a release when the wind is coming from the prevailing easterly direction, it is just a matter of time before existing records are broken.
So next time the winds are up, if you want to come and support the BOM team's sporting endeavours or just have a good laugh, head on up to the balloon shed.
The Casey ANARE 77 BOM team.
