Indigenously fixed German radar back in Chennai

S-band Doppler Weather Radar, which developed a snag in 2018, covers about 250 km from south TN to Vizag
(Left) S Balachandran, Head, RMC and (Right) M Mohapatra, Director General of Meteorology, IMD | R Satish Babu
(Left) S Balachandran, Head, RMC and (Right) M Mohapatra, Director General of Meteorology, IMD | R Satish Babu

CHENNAI: More than 20 years after the country’s first Doppler Weather Radar (DWR) was installed at the Port Trust of India office in Chennai, the German-made S-Band DWR, which encountered a technical snag in 2018, was indigenously renovated and restored on Saturday.Dr M Mohapatra, Director General of Meteorology, termed it as a testimony to the technical capability of India.

B Arul Malar Kannan, scientist in-charge of DWR facility, said IMD officials initially approached a German firm to supply the faulty part, slew ring bearings (SRB), and fix the radar. “Initially, we found the oil that we were using turned into a tar-like substance due to temperature. The bearings used in the antenna were customised by another firm. In 20 years, systems have also changed. We took immediate corrective measures and continued to operate the radar. Then, we approached ISRO Telemetry Tracking and Command Network (ISTRAC),” he said. He added the repair work cost Rs 30 lakh.

The radar covers about 250km, corrected for curvature, from the lower part of Tamil Nadu up to Vishakapattinam and has to be operated at 0.14 degrees precisely. Though officials were not worried about the cost, there are only two to three reliable firms for manufacturing bearings and they would take at least eight months to manufacture them, said VK Anandan, Deputy Director of Radar Development at ISTRAC.
“It was a challenge to manufacture the parts in the country as we don’t have much experience. We then measured the parts and customised them to ensure precision. Our efforts fit ‘Make in India’ theme,” he said.

Congratulating IMD, retired IAS officer Thirupugazh, now an advisor to TN government, said the organisation is responsible for reducing fatalities due to disasters. Talking about the accuracy of weather predictions, Mohapatra said IMD can accurately forecast 80% thunderstorms, heavy rainfall with 70%-80% accuracy (it was 60% five years ago), and predict rainfall before five days with 60% accuracy. “Time has come for using weather forecasting to reduce loss of property and improve socio-economic conditions,” he said.

The installation of C-band Doppler radar in Kalpakkam is in progress and there are also plans to procure more radars, he said. According to sources, plans are also on to procure another two S-band radars.The S-band Doppler radar being under repair became an issue after Chennai received nearly 20 cm of rain in December last year leading to severe flooding and the IMD failed to predict the sudden severe downpour. Reacting to a question about the failure to predict cloudburst, Mohapatra said small-scale weather events are difficult to predict.

“We are trying to improve. But there is still a 20% error in weather forecasting as it is not a linear science. By 2030, it will increase by about 10%-15%. Now, the forecast is provided for every 12 km and it will be reduced to six km in the coming years. We are also trying to augment radars in cloudburst-prone areas,” he said.

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