Investigation of methane flux in South Asia using atmospheric measurements at Nainital, India and global Eulerian Lagrangian coupled atmospheric model

We have conducted air samplings at Nainital, India (29.36 N, 79.46 E, 1958 m asl) to analyze concentrations of greenhouse gases (CO2, CH4, N2O and SF6), CO, H2, and isotope ratios. The air samples were collected in 1.5 L Pyrex glass flasks at weekly time intervals. Here we discuss the methane flux in South Asia using Global Eulerian-Lagrangian Coupled Atmospheric (GELCA) model with the observational data of methane at Nainital. The coupled model approach is suitable to represent observations at high spatial resolutions. The forward simulation represented a background feature of methane variations at Nainital, especially for low methane concentrations in winter. However, the simulation overestimated summer enhancement of methane concentrations. In summer, air parcels observed at Nainital were transported from Ganges basin thus the atmospheric observational data at Nainital might constrain the …