The Impact of Emissions on Tropospheric Ozone over the Indian Subcontinent

Abstract:

Asia is a region of intense solar radiation, high water vapour abundance, and consequent high photochemical activity. The anthropogenic emissions from this region continue to grow. The abundance of tropospheric ozone-a product of this photochemical activity, an important climate gas, and an air pollutant-is examined using GEOS-Chem, a global three-dimensional chemical transport model (www.geos-chem.org). We have examined ozone abundances in the boundary layer, and mid and upper troposphere over the Indian subcontinent, a region with rapid growth in industrial, urbanization, transportation and agricultural activities. The work focuses on the export and import of tropospheric ozone and its precursors, out of and into the Indian subcontinent. The model simulations are compared against a comprehensive data set on ozone from soundings, MOZAIC aircraft data, and surface observations. Detailed modeling studies that enable an understanding of the impact of emission (particularly NO_x) on tropospheric ozone are evaluated for the period of 15 years (2000-2014), when emissions were increasing rapidly. Modeling runs were conducted with emissions removed, emissions included, and emissions scaled by certain factors to study the sensitivity of ozone abundances to emissions from various regions of interest.