This week the dive team gets a helping paw, we learn a bit more about weather forecasting, and see some great shots of the turning seasons.

Dive project a howling success

This week saw a valuable addition to the Casey summer dive team.

Fearing that time would run out before they had completed their work this summer, project chief Jonny S, collared one of the best commercial divers in the business, Stay, to help get them over the line.

Not wanting to be in the dog house with everyone’s friends at polar medicine, Stay insisted on a full dive medical before she took to the icy waters. Apart from some awkward moments during her temperature reading, Stay was announced fit and well by dive doctor, Lizzie.

The dive program has been running at a very high tempo all summer, and the dive team, lab workers, support staff and others on station have really excelled in their efforts to get the project completed.

In simple terms, the experiment is about simulating what effects increased C02 levels are likely to have on the environment, by placing underwater experiments on the sea bed in O'Brians bay, just south of station.

Despite some initial nerves, Stay’s Labrador genes really kicked in, and she took to the water like the pro she really is — dog paddling of course.

Season turning

Now the bulk of the summer people have left, it seems very quiet around the red shed (accommodation building), often finding yourself the only one around. The work has changed as well, as most of us are focused on preparing for the winter months. Vehicles need stowing away, sheds need packing and loose items are locked away in anticipation of the big snow falls and high winds to come.

The upside of the slow down is that it has allowed us to really enjoy the environment we see everyday. With temperatures starting to drop and days getting shorter, most have seen their first stars for four months and it wont be long until the sky is filled with colour from auroras. The sea has started to freeze at night causing pancake ice but it will be a while yet before it is solid enough to walk on.

For now we have some lovely sunsets and evenings which are still warm enough to enjoy a walk to the wharf in the hope of seeing seal or penguin.

Aviation weather explained

As the last A319 flight for the season approaches we review the weather aspect of supporting a flight.

In the days leading up to an A319 flight, the weather crew at Casey slip on their capes and slide smoothly into hyper-drive. Four days before the flight is scheduled, they start to deliver forecasts to the A319 crew and Australian Antarctic Division operations with their first expectations for the weather on flight day. That many days ahead, the forecast is not detailed.It just gives a general idea, which is then developed and tweaked, increasing the accuracy day by day until the day before the flight. At this point in time we ‘man all stations’ extending our coverage hours and issuing six-hourly forecasts in great detail using standard aviation codes. The scheduled flight day arrives and the morning forecaster is in the office at 0300 (four hours before take off for a scheduled 0700 departure to Tasmania), ready to receive visual observations from the Wilkins crew, and to finalise the flight briefing package for the pilots before the aircraft departs.

Once ‘Snowbird’ takes flight, the forecasters breathe a sigh of relief, take another breath, then launch themselves into flight-watch operations! Flight-watch consists of monitoring the actual weather along the flight route and comparing that to the forecasts to ensure that the forecast is correct within amendment limits (for example, the forecast pressure must be within two hecto-pascals of the actual pressure, or the forecast must be redone and the pilots updated). Satellite pictures are used to indicate the weather along the route, along with surface observations of wind strength and direction, surface contrast and horizon definition, temperatures, cloud base heights and amount of cloud, horizontal visibility, present weather (Is it snowing? Or foggy?) and pressure. Any of these elements can affect the success of the flight, so they are closely monitored and passed onto the flight crew.

The weather crew supporting an A319 flight includes the trained observers on the ground at Wilkins, the forecasters and observers at the Antarctic Meteorological Centre (Casey weather office and/or Davis weather office), and aviation staff at the Bureau National Operations Centre in Melbourne who are responsible for aviation weather warnings for the high level flights.

After about 4.5 hours of flight, ‘Snowbird’ will land at Wilkins. The forecaster on duty will then ensure that the aircraft has all the necessary weather information for the flight back to Hobart, Tasmania. This includes the latest aviation forecast issued for Hobart, Launceston, Melbourne and Adelaide, ensuring that once ‘Snowbird’ leaves the ice, they have a safe place to take their passengers home to. The forecaster continues to monitor the weather for ‘Snowbird’ until the aircraft is north of 50S, at which point the Antarctic forecasts and high level warning products are cancelled, and the weather team take take a well earned break.