Abstract
ABSTRACT In this study, we categorized detailed mass-based emission factors (EFs) by age, calculated new estimates of fuel use, and developed spatially resolved emission inventories of constituents (PM2.5, black carbon [BC], and organic carbon [OC]) in the fine aerosol generated by the on-road transport sector in India. On a national level, this sector released an estimated 355 (104–607) Gg y–1, 137 (47–227) Gg y–1, and 106 (34–178) Gg y–1 of PM2.5, BC, and OC, respectively, for the base year 2013, contributing nearly 7%, 17%, and 6% of the total emissions for each constituent. Although super-emitter vehicles comprised only 24% of the total traffic volume, they were responsible for 67% and 47% of the national PM2.5 and BC emissions, respectively, which indicates that eliminating these vehicles may rapidly reduce emissions from the on-road transport sector in India. To predict the direct radiative forcing (DRF) from BC emissions in this sector, we then input emission estimates for the carbonaceous aerosols into the Community Atmosphere Model (CAM5) global climate model and found a positive DRF of up to 6 W m–2 at the top of the atmosphere (TOA) and a negative DRF of up to 10 W m–2 at the surface, suggesting that as much as 16 W m–2 of energy remains trapped within the atmosphere. With the rapid economic growth and continued urbanization, the transport sector in India is likely to further expand in the future and hence requires immediate attention in order to reduce the BC burden and improve air quality in the nation.
Highlights
Development of a regionally representative emission factors (EFs) database is a prerequisite for preparing reliable emission estimates of anthropogenic aerosols and their precursors gases that are key input to climate models which are used as a tool for carrying out climate assessments (Reynolds et al, 2011; Bond et al, 2013; Pandey and Venkataraman, 2014)
Due to incorrect emission estimates of carbonaceous aerosols from South Asia, most climate models underestimate the aerosol burden over the region in their simulations and these models are generally associated with large uncertainty in terms of both magnitude and sign of climate forcing due to aerosols over South Asia (Bond et al, 2013)
Using detailed EFs for on-road vehicles categorized by age to decrease the uncertainty associated with the emission estimates, new emission inventories for the PM2.5, BC, and OC for the on-road transport sector in India during 2013 were developed
Summary
Development of a regionally representative EFs database is a prerequisite for preparing reliable emission estimates of anthropogenic aerosols and their precursors gases that are key input to climate models which are used as a tool for carrying out climate assessments (Reynolds et al, 2011; Bond et al, 2013; Pandey and Venkataraman, 2014). Due to incorrect emission estimates of carbonaceous aerosols from South Asia, most climate models underestimate the aerosol burden over the region in their simulations and these models are generally associated with large uncertainty in terms of both magnitude and sign of climate forcing due to aerosols over South Asia (Bond et al, 2013). Recently refined regional emission inventories (Pandey and Venkataraman, 2014) used the Tier III approach (IPCC, 2013) in the inventory development
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