The Doppler radar that the city has been waiting for ever since the July 2005 deluge, finally started receiving its first signals from the skies at 5.30 pm on Friday. This means from next year on, Mumbai will be much better prepared for the monsoon.
“The radar has started transmitting radio waves that are reflected from the clouds and moisture particles,” said R V Sharma, deputy director general, western region, India Meterological Department. “It’s a milestone,” he said.
While the S-band Doppler radar has started operating, there is still some time before it starts recording observations. That’s because the signals are being further fine-tuned and adjusted further for accuracy. The radar is also functioning on low voltage and will progressively move to full voltage.
In the second week of November, the department will carry out a Site Acceptance Test to check if the various parameters prescribed and accepted in the purchase order by Bangalore-based Bharat Electronics Limited, manufacturer, have been met.
“After this, the radar will undergo an endurance test where it won’t shut down for 72 hours. If it passes the test, the radar will start making observations,” Sharma said.
At a height of 16 metres and a range of up to 400 metres, the S-band Doppler Weather Radar at Navy Nagar, the Doppler radar can forecast at a short range within six hours.
The radar emits billions of microwaves that look inside moving weather systems and bounce back signs of a particular kind of weather condition that forecasters analyse to make predictions. It can also transmit information about a cloud activity of around 250 km from the area, its distance from land, its composition as well as the number and size of water droplets found in a cloud.
Predictions will be faster because the radar can provide quick measurements of rainfall intensity and wind speed. Unlike satellites that take 15 minutes to half-an-hour to relay real-time data on approaching turbulent thunderstorms or cyclones, the remote sensing device can update such information every five minutes.
“The radar will monitor rainfall intensity from the time it starts raining rather than after it rains. So, one can have an early warning of increased rainfall,” said Professor Kapil Gupta of IIT-Bombay who designed the monsoon website for the civic corporation.
According to a recent study, radar can pinpoint where the rain will accurately fall from the present 200 km range to 75 km (which means that the rainfall prediction can be narrowed down area-wise will be even more precise).