Seasonal distribution of ozone and its precursors over the tropical Indian region using regional chemistry-transport model

Abstract

An off-line regional chemistry-transport model (REMO-CTM) has been applied for the first time to the Indian geographical region to simulate the distribution of ozone and its precursors at the boundary level. The model accounts for the winds from ECMWF as lateral boundaries and latest emission inventories of the ozone precursors for the year 2003. An attempt has been made to validate the model with meteorological parameters like precipitation data and wind fields available from observations, satellite data for CO, and that of surface ozone observations over different parts of India. Model results reproduce the precipitation pattern reasonably well. The qualitative agreement of model and ozone data is also found to be reasonable. Present results are also compared with the global chemistry transport model. The seasonal distribution of ozone and its precursors over the Indian region indicates a differential pattern driven by the spatial synoptic weather condition and local emissions. The continental tropical convergence zone (CTCZ) and long-range/regional transport also play an important role, especially over the Indo-Gangetic plains where the ozone, CO, and NO_x concentrations are found to be higher as compared to other parts of India.