Variations in surface ozone and NO^sub x^ at Kannur: a tropical, coastal site in India

• Published in: Journal of atmospheric chemistry Vol. 69; no. 2; p. 101
• Main Authors: Nishanth, T, Satheesh Kumar, M K, Valsaraj, K T
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01-06-2012
• Subjects: Air flow; Air masses; Air pollution; Atmospheric chemistry; Correlation coefficient; Emission measurements; Meteorology; Nitrogen dioxide; Ozone; Photolysis; Urban areas
• ISSN: 0167-7764; 1573-0662
• DOI: 10.1007/s10874-012-9234-5

Continuous measurements of surface ozone (O3), NOx (NO + NO2) and meteorological parameters have been made in Kannur (11.9 °N, 75.4 °E, 5 m asl), India from November 2009 to October 2010. It was observed that O3 and NOx showed distinct diurnal and seasonal variabilities at this site. The annual average diurnal profile of O3 showed a peak of (30.3±10.4) ppbv in the late afternoon and a minimum of (3.2±0.7) ppbv in the early morning. The maximum value of O3 mixing ratio was observed in winter (44±3.1) ppbv and minimum during monsoon (18.46±3.5) ppbv. The rate of production of O3 was found to be higher in December (10.1 ppbv/h) and lower in July (1.8 ppbv/h) during the time interval 0800-1000 h. A correlation coefficient of 0.52 for the relationship between O3 and [NO2]/[NO] reveals the role of NO2 photolysis that generates O3 at this site. The correlation between O3 and meteorological parameters indicate the influence of seasonal changes on O3 production. Investigations were further extended to explore the week day weekend variations in O3 mixing ratio at an urban site reveals the enhancement of O3. The variations of O3 mixing ratio with seasonal air mass flows were elucidated with the aid of backward air trajectories. This study also indicates how vapor phase organic species present in the ambient air at this location may influence the complex chemistry involving (VOCs) that enhances the production of O3 at this location.[PUBLICATION ABSTRACT]