Diurnal and seasonal variability of CO 2 and CH 4 concentration in a semi-urban environment of western India

Amongst all the anthropogenically produced greenhouse gases (GHGs), carbon dioxide (CO 2 ) and methane (CH 4 ) are the most important, owing to their maximum contribution to the net radiative forcing of the Earth. India is undergoing rapid economic development, where fossil fuel emissions have increased drastically in the last three decades. Apart from the anthropogenic activities, the GHGs dynamics in India are governed by the biospheric process and monsoon circulation; however, these aspects are not well addressed yet. Towards this, we have measured CO 2 and CH 4 concentration at Sinhagad, located on the Western Ghats in peninsular India. The average concentrations of CO 2 and CH 4 observed during the study period are 406.05 ± 6.36 and 1.97 ± 0.07 ppm (µ ± 1σ), respectively. They also exhibit significant seasonal variabilities at this site. CH 4 (CO 2 ) attains its minimum concentration during monsoon (post-monsoon), whereas CO 2 (CH 4 ) reaches its maximum concentration during pre-monsoon (post-monsoon). CO 2 poses significant diurnal variations in monsoon and post-monsoon. However, CH 4 exhibits a dual-peak like pattern in pre-monsoon. The study suggests that the GHG dynamics in the western region of India are significantly influenced by monsoon circulation, especially during the summer season.