Abstract Number: 843 Working Group: Aerosol Physics
Abstract Aerosols are ubiquitous in nature and play a very important role in radiative forcing, climate change, visibility impairment, reduction in rain intensity and health-related issues. Aerosols have the variable behaviour of absorption and scattering of radiation due to nature of chemical constituents. Hence, estimation of radiative forcing of aerosols is important for which study on physical and chemical properties of aerosols is necessary. A systematic and long-term study on the understanding of properties of aerosols and its radiative forcing has been carried out at Agra over the Indo-Gangetic basin. The measurements of the mass concentration of aerosol (PM10 and PM2.5), black carbon (BC) and Aerosol Optical Depth (AOD) and monitoring of meteorological conditions have been performed. The mean concentration of PM10 (185.8 μg m-3), PM2.5 (94.2 μg m-3), black carbon (8.3 μg m-3) and AOD (0.93) has been determined. The concentration of PM10 and PM2.5 is 2-3 times higher than the NAAQS standard and 7-8 times higher than WHO standard. The high load of aerosol may be due to excessive vehicular emissions and road paved dust. Agra is surrounded by Rajasthan and lots of sand particles released from the grinding of marbles and red stone might be contributing towards a high load of aerosols. Black carbon concentration during night time may be also attributed to the increase in biofuel/biomass burning, especially for cooking as well as for heating purposes. The presence of fine mode particle enhances the radiance scattering and therefore, the aerosol optical depth (AOD) values are high at the shorter wavelength. Aerosol optical depth has been shown relatively strong wavelength dependence of optical depth at shorter wavelengths that generally decreases towards longer wavelengths irrespective of the seasonal change.