IMD’s weather radar goes defunct when needed most, again

The city’s doppler weather radar (DWR) operated by the India Meteorological Department (IMD) in Colaba became defunct late on Sunday, drawing the ire of several independent meteorologists tracking the path of Cyclone Tauktae which passed by Maharashtra coast on Monday

The city’s doppler weather radar (DWR) operated by the India Meteorological Department (IMD) in Colaba became defunct late on Sunday, drawing the ire of several independent meteorologists tracking the path of Cyclone Tauktae which passed by Maharashtra coast on Monday.

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This is not the first time that the instrument has become dysfunctional at a crucial moment. On December 4, 2017, when Cyclone Ockhi brushed past the Mumbai coast, the radar was not functional. The radar was also not functional on multiple days during extreme rainfall events in June and July 2019, and also on June 1, 2020, about 48 hours before Cyclone Nisarga made landfall in Maharashtra.

“There are five doppler radars on the west coast, two in Kerala, one in Goa, one in Mumbai and another in Bhuj, Gujarat. While they no longer play as crucial a role in modelling paths of cyclones, DWR’s are important instruments that allow us to map these systems in real time. They are extremely valuable for planning disaster management responses. Unlike the east coast, where cyclones are extremely common, we do not have a very extensive network along the west coast. We need to actively invest in them,” said Akshay Deoras, an independent meteorologist and PhD student at the University of Reading, England.

IMD officials confirmed that DWR had stopped working on Sunday evening, but did not cite reasons for the same. “The doppler radar has run into a technical snag. Technicians are looking into the matter. We cannot say by when it will be up and running again,” said a scientist who did not wish to be identified.

Mumbai’s only DWR was installed in 2010 for weather surveillance up to 400kms from the coastline and was first recommended soon after the floods of July 26, 2005. While satellite pictures can be used in lieu of radar images, experts said, the latter is limited in value. “If an x-ray is a satellite image, then a doppler radar is a CT scan. The quality and range of data it gives is simply much better, allowing us to make better predictions about where the cyclone’s spiral banks will be located, where they will bring more rain,” said Deoras.

“With radar service not available, it becomes extremely difficult to track rain bands,” said Vineet Kumar, a scientist who researches cyclones in the north Indian Ocean for Indian Institute of Tropical Meteorology, Pune.