Forecasting for the SA Agulhas

Dec 2, 2005
Author: Ian Hunter
SA Weather Services

It is the Antarctic summer season. Time to replace the research teams and replenish the bases. Personnel - and their equipment - are increasingly being flown in from strategically-placed locations such as Christchurch, Punta Arenas and Cape Town. Flights from the Cape Town International Airport are mostly to Novolazarevskaya using Ilyushin 76 aircraft. This summer there will be a total of 6 flights from Cape Town including one Hercules C130 flight to the Norwegian Troll station. From Novolazarevskaya, feeder flights using smaller aircraft, connect with the other bases in the Dronning Maud Land region.

The 3rd Ilyushin flight from Cape Town left last Friday 25 November.

Despite the obvious value of using aircraft to get to Antarctica (it only takes 6 hours to fly from Cape Town to 'Novo'), ships are still needed to get the bulk of the cargo (fuel etc) to the bases. These ships are also required as platforms for a variety of research projects in the waters around Antarctica. Not to mention their essential role of deploying drifting weather buoys ('drifters') in the Southern Ocean.

South Africa's polar relief vessel the 'SA Agulhas' sailed from Cape Town for SANAE on Tuesday 29 November. She is equipped with a new automatic weather station and SAWS meteorological personnel will be doing radiosonde balloon soundings from the ship for the first time in several years. The upper air data will provide a particularly valuable input to the many global weather prediction models. The 'Agulhas' will also be deploying 15 'drifters' and replacing the automatic weather station on South Thule Island.

Weather forecasting is significantly more critical for an aircraft than for a large ocean-going vessel, especially when the former is preparing to land at one of the Antarctic bases with a rapidly changing weather situation. However there are times when an accurate forecast of wind and sea state can help the ship's master to plan how to adjust his speed and his route. He might decide to delay departure altogether in the case of extreme conditions being predicted. Some over-the-side research activities may be very weather sensitive.

The safety of aircraft operations over Antarctica is very much dependent on mesoscale weather prediction models covering the continent and beyond. In 2002 the 'SA Agulhas' had to undertake a winter trip to Antarctica to rescue the personnel from the ice-bound 'Magdalena Oldendorff'. Ever changing conditions in the extensive pack ice meant that the ship's helicopters had to fly relatively long distances - with little or no light and rapidly moving weather systems.

The Anarctic Mesoscale Prediction System (AMPS) was the forecast model used extensively during the above operation. It is run in Boulder, Colorado at the National Center for Atmospheric Research (NCAR). Several upgrades have been made to this model since 2002 including improved resolution and earlier availability of its outputs. It will again be very useful when the 'Agulhas' sails into high latitudes.



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