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Aerosol layer is getting thicker over India: Research

New Delhi, India: Aerosols — particles or droplets suspended in the air that impact climate  by scattering or absorbing the sun’s radiation — are increasing across India, according to a research by S. Ramachandran and his colleagues from the space and atmospheric sciences division of the Physical Research Laboratory, Ahmedabad. The research was published in Atmospheric Environment.
Scientists measured the ‘aerosol optical depth’ (AOD), the degree to which aerosols prevent light transmission by absorbing or scattering it, using data from MODIS (MODerate resolution imaging spectrometer), a key instrument aboard two US remote sensing satellites, Terra and Aqua.
The new research studied aerosols in 35 locations across India and over the summer and winter seasons, from March 2000 to February 2010. Scientists found a rise in annual AOD across 30 locations, while four — Trivandrum in the south and Chandigarh, Dehradun and Shimla in the north — showed a decline. The trends were higher in west and south India.
The annual mean (average) AOD increased by over 40 per cent between 2000 and 2009 in Jaipur, Hyderabad and Bengaluru cities. They rise in AOD over Hyderabad and Bengaluru was attributed to urbanisation and in Jaipur to increased wind speeds that threw up dust from arid soil.
Similarly, the scientists reported a rise in AOD over New Delhi, attributing it to the burning of fossil fuel and biomass, and an increasing trend in AOD in India’s northeast due to biomass-burning and forest fires.
The study found both AOD and rainfall increased in the last decade in most locations.
“Trends in aerosol characteristics on regional and seasonal scales in India, the focus of this study, are important to examine, understand and explain the effects aerosols have on summer monsoonal rainfall, and the inter-annual variations and trends in rainfall,” the report said.
Source: www.scidev.net