City needs Doppler Weather Radars

Weathermen from the India Meteorological Department (IMD) and Karnataka State Natural Disaster Monitoring Cell (KSNDMC) accept that the rainfall the city experienced on August 14 and 15 was unprecedented and beyond what they had assessed. But they also say that they have the best models to forecast weather.

But weather prediction is likely to improve only when the city and State gets their own Doppler Weather Radars (DWR). Considering the intensity of rainfall that Bengaluru receives, there is a need for one, says IMD Bengaluru Director- in- charge Sunder M Metri. He had calibrated the radars installed by the state government on temporary basis for cloud-seeding.

Ten years ago, he recalls, the government had sanctioned a place in Hessarghatta to set up the radar. But now the IDM is searching for other locations in Bengaluru and Mangaluru. The head office has assured that high quality radars will come up in these areas within the next two years.

Prof M B Rajegowda, noted agro-meteorologist and retired GKVK Registrar says although the IMD did not fail, the forecast given by the department was very general. It should have been updated later in the day. However, current models allow forecast to be made only once every six hours. Once the DWRs are in use, the forecast can be made every three hours, he points out.

Govindswamy Bala, Professor at Centre for Atmospheric and Oceanic Sciences, IISc, notes that the gradient variation is very huge within the city because of which the forecast is not accurate. The present IMD models run on a national scale. They are not mesoscale, which run on city scale. However, this scale is not available anywhere in India. Only in the United States are tornado predictions done every three hours. Bengaluru too needs a similar model where flood forecast can be given, he says.

Prof J Srinivasan, Distinguished Scientist, Divecha Centre for Climate Change, says Bengaluru does not have DWRs that can give accurate cloud range and depth. This radar can help in giving real-time distribution of liquid particles and ice in the city. This can help analyse where and when it will rain next.

These radars are now installed in all coastal states, metropolitoan and cosmopolitan cities, barring Karnataka and Bengaluru. A KSNDMC official, on condition of anonymity, blames this on the centre-State politics. “Just like IMD we too had applied for DWR. But the State ministers said that there was no need as it was the domain of the IMD alone. We know that the State can easily purchase one. But they are demanding one from the Centre instead,” the official says.