Volume 12, No. 6, December 2012, Pages 1081-1094 PDF(1.47 MB)
Analysis of Diurnal and Seasonal Behavior of Surface Ozone and Its Precursors (NOx) at a Semi-Arid Rural Site in Southern India
B. Suresh Kumar Reddy1,3, K. Raghavendra Kumar1,4, G. Balakrishnaiah2, K. Rama Gopal1, R.R. Reddy1, V. Sivakumar4, A.P. Lingaswamy1, S.Md. Arafath1, K. Umadevi1, S. Pavan Kumari1, Y. Nazeer Ahammed5, Shyam Lal6
1 Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 055, Andhra Pradesh, India
2 Institute of Environmental Engineering, National Chiao Tung University, No. 1001, University Road, Hsinchu 300, Taiwan
3 Institute of Low Temperature Science, Hokkaido University, Sapporo 060 0819, Japan
4 School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Durban 4000, South Africa
5 Atmospheric Science Laboratory, Department of Physics, Yogi Vemana University, Kadapa 516 003, Andhra Pradesh, India
6 Space and Atmospheric Sciences Division, Physical Research Laboratory, Ahmedabad 380 009, Gujarat, India
Surface measurements of O3, NO, NO2 and NOx have been made over a semi-arid rural site, Anantapur (14.62°N; 77.65°E; 331 m asl) in southern India, during January-December 2010. The highest monthly mean O3 concentration was observed in April (56.1 ± 9.9 ppbv) and the lowest in August (28.5 ± 7.4), with an annual mean of 40.7 ± 8.7 ppbv for the observation period. Seasonal variations in O3 concentrations were the highest during the summer (70.2 ± 6.9 ppbv), and lowest during the monsoon season (20.0 ± 4.7 ppbv), with an annual mean of 40.7 ± 8.7 ppbv. In contrast, higher NOx values appeared in the winter (12.8 ± 0.8 ppbv) followed by the summer season (10.9 ± 0.7 ppbv), while lower values appeared in the monsoon season (3.7 ± 0.5 ppbv). The results for O3, NO and NO2 indicate that the level of oxidant concentration ([OX] = NO2 + O3) at a given location is the sum of NOx-independent “regional contribution” (background level of O3) and linearly NOx-dependent “local contribution”. The O3 concentration shows a significant positive correlation with temperature, and a negative correlation with both wind speed and relative humidity. In contrast, NOx have a significant positive correlation with humidity and wind speed, and negative correlation with temperature. The slope between [BC] and [O3] suggests that every 1 μg/m3 increase in black carbon aerosol mass concentration causes a reduction of 4.7 μg/m3 in the surface ozone concentration. A comparative study using satellite data shows that annual mean values of tropospheric ozone contributes 12% of total ozone, while near surface ozone contributes 82% of tropospheric ozone. The monthly mean variation of tropospheric ozone is similar to that tropospheric NO2, with a correlation coefficient of +0.80.
Surface ozone; Nitrogen dioxide; NOx; Oxidant; Tropospheric ozone.