Observing Source Distributions, Interannual Variability and Transport Pathways of NO<sub>x</sub> over India During 2003-2011 Using SCIAMACHY

The combustion of fuels, and biomass and certain industrial activities release highly toxic air pollutants in the natural environment. Nitrogen dioxide (NO<sub>2</sub>) is also an important trace gas pollutant affecting the climate. In India air pollution is monitored by various government organizations with innovative technologies developed by private sector. Such monitoring networks and tools provide necessary data to be used to frame policy decisions and communicate air quality status to the public at large. It is necessary to know the exact causes and factors responsible for air pollution in India due to certain activities as mentioned earlier. So that people could choose their mode to avoid or minimize the air pollution by adopting suitable actions by them. In this paper, Scanning Imaging Absorption Spectrometer for Atmospheric CartograpHY (SCIAMACHY) is used to observe tropospheric NO<sub>2</sub> during 2003-2011 over India. The highest tropospheric NO<sub>2</sub> concentration (153-137 µgm<sup>–3</sup>) is observed in the summer season of 2010-2011 over Northern Indo Gangetic (IG) plain. The NO<sub>2</sub> mixing ratios at 350 hPa during November-May for 2003-2011 over Arabian Sea ranged from 200-230 µgm<sup>–3</sup> and 90 µgm<sup>–3</sup> over Bay of Bengal. It also observed that the NO<sub>2</sub> mixing ratios decreased 80-110 µgm<sup>–3</sup> over the Arabian Sea and 80 µgm<sup>–3</sup> over the Bay of Bengal due to thunderstorms and long range transport of pollutants during monsoon season. These data may be useful for India’s National Clean Air Programme to be used for control of vehicular emissions and industrial emission.