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26 February 2003, 09:50 am
John Bilger Explains the Compexities of Weather Forecasting
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Alinghi Weather HeadJohn Bilger

America's Cup

It's been almost a week since Alinghi beat Team NZ in Race 3 to go 3-0 on the scoreboard. Hopefully the race committee will get Race 4 underway tomorrow, Thursday 27 February.
Weather forecasting for the America's Cup has become monumentally complex, utilizing space shuttle technology, fleets of up to eight weather boats, exclusive agreements with international R&D organizations and still, the teams don't always get it right for the entire day.

A good example was the low pressure system that came through yesterday, Tuesday. According to the Alinghi weather team, it was actually situated slightly east to what the model predicted, the winds were more southeast and lighter than predicted in the afternoon.

Alinghi weather specialist Jon Bilger agreed that logistics aside, it would have been possible to race yesterday.

Even so, the detail surrounding the collection of weather data is huge and given the complexities of the Hauraki Gulf, Alinghi went for gold when they picked their weather team, hiring seven New Zealanders of the nine-person Swiss weather team.

Jon Bilger and Jack Katzfey of the Alinghi weather team are not only skilled sailors but also experts in the area of weather forecasting. To take some of the mystery out of what's involved in the seemingly complex weather analysis used by the teams, Bilger and Katzfey discussed the routine in the Alinghi camp.

The Swiss weather team relies on three key tools to provide it's sailing team with up to date weather information: they strive to get the best data, they strive to develop and utilize the best information, and they have developed what they consider to be the most qualified team to manage the information.

Like the Team New Zealand and the other challengers, Alinghi sends its weather boats out to the Hauraki Gulf early in the morning to collect data. When Alinghi first started training on the Gulf, they used four weather boats and built that fleet to eight about eight months ago.

According to Bilger, the weather boats are a primary source of information for the team and play a key role in facilitating the transfer of huge amounts of weather information up and down the course. Their positions on the course are determined by the wind direction and while the boats typically don't anchor because of the no-anchor zones on the course, sea parachutes are used to slow the boats down.

In the 8:30am brief with the weather team, the afterguard and trimmers, the team start to look at the expected trends in the weather for the start of the race. "We also look for windspeed in terms of sail selection so that we get the right sails on board for the race," explained Bilger.

The race boats receive exactly the same information as the weather teams but close to a start the afterguard don't have the time to analyze it so they rely on the verbal advice of the weather teams. While their main job is to ensure no surprises for the sailors on the course, the primary emphasis for the weather teams is on relaying first beat information while keeping sailors aware of any changes expected to come through.

"There's a lot of emphasis on the first beat because if you can get a big jump on there, it can make a big difference to the race," said Bilger.

The many weather stations in the immediate Hauraki Gulf are located very close to the race area and provide very reliable information for making predictions. These sites include the Met stations sites, sites are shared with Team NZ and OneWorld, and additionally, Alinghi has it's own sites, their whereabouts they weren't willing to share.

"We also share with Team NZ and all the other challengers except Oracle BMW the weather buoy out in the Hauraki Gulf which collects data 24 hours a day, critical for looking at the weather patterns and seeing how the numerical modeling pattern is going," said Bilger.

One of the key aspects of Alinghi's weather program is the numerical modeling technology developed by CSIRO, the Australian-based Commonwealth Scientific and Industrial Research Organization with whom Alinghi have an exclusive agreement.

"It's very innovative and cutting edge technology that takes into account all the geographic and atmospheric processes and creates forecasts for the day, and also for the week," explained Bilger, "We have the ability to zoom in over the race course area which gives us the ability to see the fine detail in terms of currents and geographic effects of sea breezes."

The other high tech contribution to the Alinghi weather program is the wind profiler that measures the direction in the last two kilometers every 100 meters, which Alinghi also shares with Team NZ. It's located on an island in the Gulf and comprises a large antennae array, 16 meters by 16 meters, with a housing for the actual computers. The equipment was developed and constructed by an Australian company, ATRAD (Atmospheric Radar Systems), and shipped to New Zealand for the Cup.

The information from the wind profiler is broadcast back to the weather teams via cell phone. The wind profiler measures direction and windspeed every 100 meters going up into the atmosphere by transmitting an electric magnetic variation into the atmosphere, the Doppler effect providing the windspeed and direction. The information is broadcast back to the weather teams via cell phone. Bilger compares the technology as similar to sonar while utilizing a different frequency and shorter range.

All information comes in automatically through a cell phone network and all the data is transmitted electronically and then relayed back to the race boats. Information security is tight out on the course with the cell phone network and radios encrypted.

"You do have a lot of information coming in and it's a case of looking at what's most relevant,"said Bilger. "At the end of the day, every day is different. There are some trends you can rely on but you need to keep an open mind."

Bilger wouldn't disclose details regarding cost of the Alinghi weather program but felt it was suffice to say, "It's less than you think."
Michelle Slade - ©
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