Optical particle sensor based measurement and analysis of atmospheric aerosol number concentration of various sizes over a tropical region of Northern India

The measurement of atmospheric aerosol number concentration has been carried out at a remotely polluted site (Roorkee, 29º 52’ N, 77º 53’ E, 275 m above mean sea level) in northern India during pre monsoon period of 2009 at a height of 9 m above ground level. The aerosol number concentration having different sizes (0.3-0.5, 0.5-1.0, 1.0-2.0 and 2.0-5.0 μm) in pre monsoon summer season 0f 2009 has been analyzed, and the daily variation of aerosol number concentration has been related to selected meteorological parameters like as relative humidity, temperature, rainfall and wind speed. The measurements were made with an optical partical counter. The aerosol number concentration for upper size ranges (1.0-2.0 and 2.0-5.0 μm) is maximum in June and minimum in July. The aerosol number concentration in small size ranges (0.3-0.5 and 0.5-1.0 μm) decreases monotonically till the end of July.