Abstract
The study assesses the usefulness of 2 currently operating CO2 monitoring stations over India using multi-particle back-trajectory analysis derived from the FLEXPART Lagrangian particle dispersion model. The 2 receptors are located at Hanle (HLE) and Cape Rama (CRI); the former is located at the foothills of the Himalayas and the latter is a coastal site near Goa. The particle back-trajectories reaching HLE indicated that probable source regions for CO2 are primarily from northern Africa, the southwestern Eurasia and the south Asian subcontinent. The back-trajectories further indicated a descending pattern from the upper troposphere. Irrespective of the differential flow patterns during summer (June to September) and winter (December to February), the indicated source regions in HLE are nearly similar throughout the year. On the other hand, the source regions in CRI respond to the differential flow pattern, and are primarily from the northeastern part of India during winter and from the southern tropical Indian Ocean during summer. The dispersion in the back-trajectories reaching CRI is relatively smaller than at HLE. This study indicates that the location of CRI (HLE) is appropriate for capturing the regional emissions of CO2 and their short- (long-)range transport from the lower (upper) troposphere. The receptor at CRI was more representative of boundary layer fluxes, while the receptor at HLE was representative of both the boundary layer fluxes and background concentrations from the upper troposphere.