New radar captures tornado

Only a week after their custom-built mobile weather radar had been finished and newly deployed out at the University of Auckland's Ardmore field site, a tornado whirled through.

"The radar was only one and half km from the tornado and we probably got the best high resolution computer images of a tornado that have ever been recorded," enthuses Prof Geoff Austin (Geophysics), who designed the concept for the machine in the early 1990s.

"We could set the radar up in the same muddy field and wait another 200 years to get recordings like that again. It just shows science is a combination of good luck as well as doing good science."

The $500,000-plus radar, funded by overheads on a series of research contracts from the Public Good Science Fund and field deployment of an earlier radar in Australia's Snowy Mountains, is the latest tool Geoff and the Atmospheric Physics Group are using in their research program on cloud physics.

Built over a year by a team in the Physics Mechanical Workshop that included manager Steve Warrington, apprentice Matthew Hogg, senior technical officer Kevin George and radar engineering specialist Ian Guthrie and using software designed by physics PhD student Andrew Peace, the mobile radar can be used in rugged and extreme conditions.

"It can go anywhere a four-wheel drive can," says Geoff, "and will be particularly useful in predicting heavy rainfall in coastal ranges where strong winds force moist air upwards, resulting in strong orographic rainfall."

The radar works by sending out microwave signals (short-length radiowave signals) which interrogate clouds and reflect off raindrops and snowflakes.

"By scanning the antenna we can get 3D images of the cloud on our computer and show how much water is in the cloud, which means we'll be able to more accurately predict heavy rainfall and flooding."

As well as providing information for NIWA on local cloud formations, the mobile radar is in hot demand overseas and has been designed to travel.

Its control and display are integrated into a single computer allowing remote operation and data retrieval from anywhere in the world via the web.

It also has heaters and air conditioning to allow operation in all climates and it can be packed into a standard shipping container for field experiments overseas.

Late in 2005, it was due to travel to Britain with a PhD student to help record data during experiments on flooding in the Pennines led by the University of Newcastle.

In the future, it will be deployed to Fiji to study tropical cyclones and to Australia where it will be used in experiments led by the Australian Bureau of Meteorology Research Centre looking at cyclones and thunderstorms near Brisbane.

The group has also had several requests to build radars for sale but so far these have been declined.

To see the mobile weather radar in action go to www.eequalsmcsquared.auckland.ac.nz