Making sense of weather SANJEEB MUKHERJEE

Thanks to a quantum leap in technology, the India Meteorological Department is now able to make accurate weather forecasts and issue early disaster warnings

Back in 2006, when a weather station under the centuries-old India Meteorological Department (IMD) collected any information on weather, it had to manually analyse the datasets and share it with its national bureau for dissemination.

It was a painfully slow task and needed a huge number of people to perform it. So much so that at many observatories scientists worked in three shifts to collect and analyse weather data.

That was then. Today, almost all of the IMD’s operations are automated using its own dedicated virtual private network (VPN). The data is collected and shared automatically, freeing up staff and cutting out the need for shifts. This has also speeded up the process of sharing information with the forecasting desks. The result: the Met department’s forecasting capabilities have improved dramatically in recent years.

This has been further helped by the fact that its High Performance Computing (HPC) support jumped from 125 gigaflops a decade ago to 8000 gigaflops in 2018, enabling it to process about 1000 waves of weather data at one go.

The real time weather data acquisition from INSAT 3D and 3DR satellites with 15-minute update cycles has been a huge advantage as well. It has given the IMD access to pictures of the three-dimensional structure of the atmosphere, which is critical for accurate weather forecasts. When the fourth INSAT satellite is launched in 2024, it will be a further boost for the IMD.

That’s not all. The Met department has started deploying GPS-mounted sondes — a sort of meteorological balloons — to track weather movement from above the cloud level. The exercise is now carried out twice daily at 11:30 am and 1:30 am at 43 observatories. IMD sources say that the capability will soon be extended to 55 observatories.

Apart from sondes, the number of radars used to map weather conditions has also gone up from just four in 2006-2007 to more than 27 across the country now.

“These radars are in addition to the Doppler radars being installed by the meteorological wing of the Indian Air Force (IAF) which will also be used for weather forecasting,” says IMD director general K J Ramesh.

The ministry of earth sciences (MoES) — IMD’s nodal ministry — plans to map the entire country with Doppler radars by 2020. Ten of these would be installed in Uttarakhand, Jammu and Kashmir, Himachal Pradesh and the Northeast to monitor extreme weather conditions. “Since extreme weather events such as snowfall or cloudburst are common in hilly areas, these radars would be of immense help to forecast these events,” Ramesh says.

All older generation radars, placed at major airports, could only monitor thundercloud development in the area.

The new Doppler radars, on the other hand, are the most sophisticated 24x7 weather surveillance technology options available. With these, India runs global scale prediction models at 12km grid scale for the next 10-day predictions and probability predictions of heavy rainfall and severe weather conditions at 12km grid scale for the next seven days. IMD also provides oceanatmospheric models at 50km grid scale for next three-week time period and weekly and monthly rainfall and temperature predictions.

Very soon, IMD will start operating one-km grid scale forecast models for mega cities, which is in keeping with its plan to provide focused, accurate forecasts at the local level.

But the weather office has not only armed itself with state-of-the-art radars. It has also acquired a data processing capability of 8 petaflops or 8000 gigaflops. “Such high-speed computing not only processes millions of datasets in double quick time, but also helps make fast and reliable forecasts for a variety of weather events over a much more localised area,” Ramesh says.

The computing power was enhanced after the MoES installed two new super computers called ‘Mihir’ and ‘Pratyush’ at its centres in Pune and Noida in January this year. The supercomputers, which cost ~4.5 billion, are set to fundamentally alter the manner in which weather forecasting is done in India.

The other significant improvement in the IMD’s capabilities has been in the area of early disaster warnings. Working with the MoES and the Indian National Centre for Ocean Information Services, Hyderabad, IMD scientists are now able to predict deadly cyclones well before they occur and in the process, help to save thousands of lives.

Met officials say that it is because of their timely forecasts and coordinated action with disaster management authorities that the death toll in cyclones Phailin and Hudhud, which took place in 2013 and 2014 respectively, was limited to double digits.

“We believe this was a great coordinated achievement,” says Ramesh, adding that the IMD has now perfected severe weather Nowcast warnings at district and city levels with four to six-hour lead time for thunderstorms that come with potentially damaging wind speeds and torrential rainfall.