Analysis of Tropospheric NO sub(x) over Asia Using the Model of Atmospheric Transport and Chemistry (MATCH-MPIC) and GOME-Satellite Observations

The characteristics of nitrogen oxides in the troposphere over Asia were examined using the output from the global Model for Atmospheric Chemistry and Transport (MATCH-MPIC) along with satellite retrievals of the tropospheric nitrogen dioxide column from the global ozone monitoring experiment (GOME) satellite. The model and GOME retrieval technique are described briefly. The model simulations were compared with GOME NO sub(2) observations, and the model diagnostics of several key regional characteristics of tropospheric NO sub(x) were considered, including the mean tropospheric lifetime, the sensitivity of NO sub(x) over India to emissions from the Indian region, and the influence of lightning and source perturbations on other trace gases. Results are presented in the form of maps depicting NO sub(2) mass abundance and surface NO sub(x) emissions. Results show that the seasonal average NO sub(2) column from MATCH and GOME were comparable in magnitude, but the model showed some significant discrepancies in the month-to-month variations over India. The regional NO sub(x) concentrations over India were found to be sensitive mainly to local emissions, but a given relative change in emissions led to a 30 40% smaller relative change in NO sub(x) levels in the lower troposphere due to long-range transport and chemical feedback effects, whereas the wintertime upper troposphere was insensitive to local sources. During the summer, lightning NO sub(x) production over India increased NO sub(x) concentrations by 10 20%.