CHENNAI: Commissioning the 10th automatic rain gauge (ARG) station at the Anna University campus here on Wednesday, deputy director general of meteorology Y E A Raj said that with this facility the recording of spatial variability in rainfall, air temperature and relative humidity could be more effectively done. The data collected from the ARG is transmitted via satellite to the earth station and is then uploaded on the Met office website, http://www.imdaws.com, which will provide updated information on weather in the metropolis. Nine ARGs are already installed at Sathyabama University (the first one, commissioned on March 29, 2012), PWD Taramani, Hindustan University, LMOIS Kolapakkam, Puvirundavalli, Chembarambakkam, Puzhal, KVK Kattupakkam, and HVF Avadi.The ARG has a 2.5-metre high mast, with a transmitting antenna and a datalogger enclosure. It is supported by a 12V battery powered by a solar panel. Hourly data is transmitted at an uplink frequency of 402.76 MHz by means of a technique called time division multiple access (TDMA) to the geostationary satellite INSAT-3A, which re-transmits the data in extended C-band frequency to the receiving earth station located at Pune. Each ARG has a unique time-stamp synchronised with global positioning system (GPS) satellites. This is to avoid “data collision”. The project has been implemented under the modernisation programme of the India Meteorological Department (IMD). “A network of 1,350 satellite-based ARGs is being installed all over India with rainfall sensors in all locations and air temperature and relative humidity sensors in few crucial locations,” Raj said. Southern peninsular India will have 209 ARGs. Regional Meteorological Centre, India Meteorological Department, Chennai will be the nodal office to coordinate the installations in the southern region. Tamil Nadu and Puducherry together will have 75 ARGs including 10 in and around greater Chennai.Fifty ARGs are planned for installation in Karnataka, 54 in Andhra Pradesh and 30 in Kerala. A denser network is envisaged in Phase II with each district having a minimum of four ARGs each. This may take at least two more years to install and commission, he said.Raj said execution of the project had been tough as institutions were not aware of the advantages of an ARG. “But now the awareness is high and several private institutions are approaching us to have an ARG installed in their campus,” he said. Varsity Registrar Shanmugavel, Dean Sekar and Centre for Water Resources Director Ambujam were walked through the process by Scientist Amudha of IMD.
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