Chennai bloggers fan out into the backyard to gather crucial rainfall data

A first-of-its-kind exercise by the renowned weather bloggers of Chennai has reconfirmed that Tamil Nadu’s bustling capital city received normal rains during the just concluded North-East monsoon season.

What is remarkable here is that the bloggers ventured outside the areas of jurisdiction of the two stations run by the India Meteorological Department (IMD) to collect rainfall data from a much larger swathe. Only the Chennai Nungambakkam monitoring station registered a rainfall deficit, said Thomas Prasad, a leading data scientist and weather enthusiast, who led the bloggers’ initiative.

Thomas Prasad

The Chennai rainfall statistics would be normally driven by data logged in at the Meenambakkam and Nungambakkam stations maintained by the IMD. The Tamil Nadu State Disaster Management Authority (TNSDMA) and the IMD have together put up a number of rain gauges, but the bloggers drew down data from their own equipment at a number of places outside to study the local rainfall deviations better.

For example, a small village near the outskirts of Chennai, Ponmar, gets bountiful rain (a known source for many water supply companies) but doesn't have an official gauge. The same goes for places such as Perumbakkam in the South and Ayyapakkam in the North.

“We hope the collection of data from places such as these will help the disaster management officials along with the IMD to identify the requirement in terms of drought and flood relief,” Prasad told BusinessLine . The intent is to cover the districts of Kancheepuram, Tiruvallur, Chennai and Chengalpattu and build and maintain a database for the future. This would help identify vulnerable places for extreme weather.

“The holistic view emerging from our exercise suggests that Chennai got normal rains with only Nungambakkam and some regions to its West being an aberration,” Prasad said. He added that it had also rained mostly normal or above in the lakes and the catchment areas.

Unique monsoon

The 2019 monsoon was unique in that except Chennai Nungambakkam, it either rained normally or in excess. This is the first ever time that the bloggers sought to consolidate rainfall numbers from their own automatic weather stations or rain gauges and track down and consolidate numbers at the taluk/zone levels. In doing so, they also assimilated official data both from the IMD and the TNSDMA. VV Prasad and Ram Kumar were in charge of collection and compilation of data.

They also drew extensively from the data storehouse meticulously managed by a prominent member of the blogging community — who preferred to remain anonymous — as well as the KEA blogging community, another leading purveyor of Chennai weather. It was at the annual North-East monsoon stock-taking meeting of bloggers towards the end of 2019 that Prasad and fellow bloggers struck upon the idea of compiling and publishing Chennai rainfall data including from areas outside IMD’s purview. The latter has very little infrastructure in capturing rainfall events in Chennai, Prasad said.

The bloggers’ effort drew plaudits from former IMD Director-Generals KJ Ramesh and Air Vice Marshal (Retd) Ajit Tyagi. While lauding the Chennai bloggers for their excellent work, Tyagi observed that this needs to be replicated by other cities.

Multi-discipline collaboration

Apart from being a passionate data scientist, Prasad is a founding member of the Climate-Resilient Observing Systems Promotion Council (CROPC) along with Col Sanjay Srivastava. He also manages a nationwide weather platform called Weather Basics, which actively collaborates with the IMD, private forecaster Skymet Weather, The Weather Company, an IBM Business, a host of leading weather institutions, top academicians, leading national media houses, various departments under the Union Ministry of Earth Sciences and NGOs as well as disaster risk management institutions under the State and Central governments.

The weather across India as well as global extreme events are discussed threadbare on this platform, which has made Weather Basics one of the most sought-after WhatsApp groups on weather. The CROPC, in collaboration with IMD, IIT-Delhi and the India Meteorological Society, has also launched a countrywide campaign on lightning resilience and brought out a nationwide lightning impact report for South-West monsoon, 2019.

Prasad’s passion for weather and expertise in analysing data have catapulted him to a niche club. The ‘Global Leader in Weather Dissemination’ award bestowed on him in absentia at an international event held last November in Azerbaijan.

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