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The Hindu
The Hindu
K. Lakshmi

100 years of weather forecasting in Chennai

In contrast to the hustle and bustle of Nungambakkam in central Chennai, the office of the Regional Meteorological Centre wears a serene look with a cluster of buildings surrounded by verdant greenery. On this premises functions the World Meteorological Organisation-recognised long-term observing station, which has made weather observations for more than 100 years.

The earliest instrument-based astronomical observations in the then Madras can be traced to 1786 at Egmore. Madras got its first scientific observatory established in the country by the British. The Indian Meteorological Department office still preserves a laminated sheet of paper that has the oldest records of Masulipatnam’s latitude and longitude taken in 1786 and 1787.

A short walk to the rear of the office leads to the relics of the yesteryear pride of the campus. A 15-foot granite pillar stands testimony to the establishment of the first astronomical observatory by the East India Company in the country. It was upgraded and shifted to this premises spread over 10 acre, which was then a ‘Garden House’, in 1792.

It was this pillar weighing 10 tonnes, erected by the then Governor of Madras, Charles Oakley, and four other structures that held astronomical instruments like altitude, transit circle and azimuth. The Madras observatory was established for ‘promoting the knowledge of astronomy, geography and navigation’ in India by the British.

The pillar has inscriptions in Tamil, Telugu and Urdu about astronomical measurements and the name of its architect Michael Topping. While the astronomical observatory and equipment were shifted to Kodaikanal in 1899, the monuments remain to tell the tales of yesteryear glory.

When the Indian Meteorological Department underwent decentralisation, the RMC, Chennai, was established. It was initially functioning in a small room and then moved to a new building in June 1960, records a handbook brought out by the Department.

Y.EA.Raj, senior meteorologist, noted that S.R. Savur assumed office as the first Deputy Director-General of Meteorology. There were even copies of his communication through telegrams about his arrival.

The Nungambakkam observatory was closed in 1943 following the Second World War and was reportedly used as a hutment for soldiers.

“It was said to be working in a rented building on Mowbrays Road or TTK Road. But there is no clarity. The RMC shifted to the Nungambakkam campus in 1948. There was also a drawing of a building that apparently functioned as the office during the 19th Century in one of the publications,” he said. By 1943, the Meenambakkam weather observatory was set up.

The RMC, Chennai, has expanded its horizon and provided meteorological and allied services not just to Tamil Nadu but also to all southern States and the Union Territories of Lakshadweep and Puducherry.

S. Balachandran, Deputy Director-General of Meteorology, Chennai, said, “We have rainfall and other weather data since 1860, with a few gaps during World War and natural disasters. We have been maintaining both manual and digital observations in many places, including Madurai and Tiruchi.”

Pointing at an ECG-like graph that had recorded wind directional changes during Cyclone Vardah, Mr. Balachandran said the manual observatories in Nungambakkam and Meenambakkam have ECG-type recorders of wind speed, pressure and direction; self-recording rain gauges and mercury thermometers. Data are collated from both kinds of observatories for weather forecasts.

The RMC maintains an optimal network of automatic weather stations and rain gauges, seismic and upper air observatories. It still releases pilot balloons with radiosonde equipment to measure weather conditions in various levels of atmosphere.

Incidentally, India’s first doppler weather radar was installed on Rajaji Salai in Chennai in 2002 for cyclone tracking and continuous weather surveillance. It replaced the S-band analogue radar that had functioned since 1972. “We have moved from analogue radars that were once used to track thunderstorms in airports to the latest technology of X band radar at Pallikaranai now,” said Mr.Balachandran.

He recalled being engaged in preparing weather charts by drawing and plotting data such as temperature variation, wind speed and pressure for weather analysis and forecast during 1992. Now, the computers do the plotting of data and even superimpose them on satellite data through a synergy forecasting system. The RMC has numerical weather prediction models and provides five types of forecasts in different time and space scales, including nowcast (within three hours), short, extended and seasonal.

With more occurrence of intense rainfall and demand for various sectoral services on the rise, the RMC is constantly evolving and expanding with services like urban meteorology, location specific- and impact-based forecast to suit the changing weather and needs of changing times.

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