Volume 12, No. 3, June 2012, Pages 344-358 PDF(1.96 MB)
Potential Source Regions Contributing to Seasonal Variations of Black Carbon Aerosols over Anantapur in Southeast India
B. Suresh Kumar Reddy1,6, K. Raghavendra Kumar1, G. Balakrishnaiah1,5, K. Rama Gopal1, R.R. Reddy1, L.S.S. Reddy1, Y. Nazeer Ahammed2, K. Narasimhulu3, K. Krishna Moorthy4, S. Suresh Babu4
1 Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 055, Andhra Pradesh, India
2 Department of Physics, Yogi Vemana University, Kadapa 516 003, Andhra Pradesh, India
3 Department of Physics, Government First Grade College, Bellary 583 101, Karnataka, India
4 Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum 695 022, Kerala, India
5 Institute of Environmental Engineering, National Chiao Tung University, No. 1001, University Road, Hsinchu 300, Taiwan
6 Institute of Low Temperature Science, Hokkaido University, Sapporo 060 0819, Japan
Continuous measurements of black carbon (BC) mass concentration performed at Anantapur [14.62°N, 77.65°E, 331 m asl], a suburban location in southeast India, using an Aethalometer from January to December, 2010, are analyzed and discussed here. The annual mean BC mass concentration ([BC]) was 3.03 ± 0.27 µg/m3 for the above study period. The sharp morning (fumigation) peak occurs between 07:00 and 08:00 h almost an hour after the local sunrise while a broad evening (nocturnal) peak is at ~21:00 h with a minimum in noon hours (14:00–16:00 h). The seasonal mean values of [BC] are 5.05 ± 0.51 μg/m3 in the winter, 3.77 ± 1.23, 1.55 ± 0.51, and 2.33 ± 0.82 µg/m3 in the summer, monsoon and postmonsoon seasons, respectively. High BC values tend to occur when the wind is directed from the 180–225° sector, which may be well defined by the geographical location of the observation site. During the winter, the trajectory air mass pathways originated through north or central India with significant advection of continental aerosols arriving before the measurement region, results in an enhanced [BC]. Whereas in the monsoon season, the pristine marine air mass from the oceanic environment led to decrease in the concentration of BC. Comparison of monthly mean variations in AOD at 500 nm and black carbon aerosols is observed to be positive with poor correlation coefficient of 0.42. The ratio of BC/PM2.5 varied from 1.3% to 7.2% with a mean value of 4.6% at Anantapur during the observation period and this ratio decreased with decreasing Ångström exponent (alpha).
BC aerosol; Potential sources regions; AOD; Ångström exponent; PM2.5.