What looks like a giant football has been helping Chennaiites know what kind of weather to expect

You may mistake the giant football-like structure atop the Port Trust Centenary building on Rajaji Salai, opposite Fort St. George for a mascot. But, this structure plays a critical role in helping Chennaiites know the kind of weather to expect. The doppler weather radar of the Meteorological department completed a decade of service on Tuesday.

Located nearly 53-metre above sea level, the ‘radome' or the radar's dome weighing 18 tonnes, continuously scans the atmosphere within the radius of nearly 500 km and provides an overview of active weather systems.

This is the first radar to have been installed in the country facing the sea on one side and the city's landscape on the other. It is from the data captured by the radar that Chennai was warned of the cyclonic storms forming in the Bay of Bengal and the thunderstorms on the surface. It is from here that data on wind speed and wind direction is transmitted almost every 10 minutes, providing information that is vital for decisions on aircrafts' landing or take off.

“The radar converts nearly 750 kilowatt power into electro magnetic radiation for tracking weather systems. A dish-like structure protected by the dome shoots out a beam of energy and transmits the echoes that are computed as data,” says S.B.Thampi, Director of Doppler Weather Radar Station.

It was this radar that tracked seven cyclones and three depressions formed over the Bay of Bengal, enabling meteorologists to issue severe cyclonic storm warnings faster. Nisha (November 2008), Laila (May 2010), Jal (November 2010) and Thane (December 2011) were some of the recent cyclones tracked by the radar.

Another special feature of the radar is its ability to detect the spatial variability and rainfall intensity across Chennai and neighbouring districts. For instance, there may be rainclouds in Ambattur, but Guindy or Nungambakkam would not get rainfall. The radar can even track the movement of clouds and predict rainfall in another area. The animated images on the website are studied by researchers,” Mr. Thampi adds.

Y.E.A.Raj, Director General of Meteorology, Regional Meteorological Centre, Chennai, says using the potential of the radar to track rainfall in various parts of the city and suburbs, the department is planning for ‘nowcasting', a short-term forecasting where weather is predicted for the next one to three hours.

“We are coming up with a technique to be adopted for analysing and forecasting the data. It would be in place in a couple of years,” he says.

The second such radar would be installed in Karaikal in two years. One more would come up in Ramanathapuram too. An official says: “Our only concern is high-rise buildings must not come in 10 km radius as it will disturb the weather monitoring.”