Ground-based in situ measurements of near-surface aerosol mass concentration over Anantapur: Heterogeneity in source impacts
Advances in Atmospheric Sciences
Aerosol and Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur, 515003 Andhra Pradesh, India; Institute of Environmental Engineering, National Chiao Tung University, Hsinchu, Taiwan; Institute of Low Temperature Science, Hokkoido University, Sapporo, 0600819, Japan; School of Physics, University of KwaZulu-Natal, Durban, 4000, South Africa; Department of Physics, Yogi Vemana University, Kadapa, 516003, India
Surface measurements of aerosol physical properties were made at Anantapur (14.62°N, 77.65°E, 331 m a. s. l), a semiarid rural site in India, during August 2008-July 2009. Measurements included the segregated sizes of aerosolsas as well as total mass concentration and size distributions of aerosols measured at low relative humidity (RH<75%) using a Quartz Crystal Microbalance (QCM) in the 25-0.05 μm aerodynamic diameter range. The hourly average total surface aerosol mass concentration in a day varied from 15 to 70 μg m-3, with a mean value of 34.02±9.05 μg m-3 for the entire study period. A clear diurnal pattern appeared in coarse, accumulation and nucleation-mode particle concentrations, with two local maxima occurring in early morning and late evening hours. The concentration of coarse-mode particles was high during the summer season, with a maximum concentration of 11.81±0.98 μg m-3 in the month of April, whereas accumulationmode concentration was observed to be high in the winter period contributed >68% to the total aerosol mass concentration. Accumulation aerosol mass fraction, Af (= Ma/Mt) was highest during winter (mean value of Af ~ 0.80) and lowest (Af ~ 0.64) during the monsoon season. The regression analysis shows that both Reff and Rm are dependent on coarse-mode aerosols. The relationship between the simultaneous measurements of daily mean aerosol optical depth at 500 nm (AOD500) and PM2.5 mass concentration ([PM2.5]) shows that surface-level aerosol mass concentration increases with the increase in columnar aerosol optical depth over the observation period. © 2012 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.