Abstract
Abstract. Intercontinental transport of atmospheric pollution (ITAP) can offset the impact of local emission control efforts, impact human and ecosystem health, and play a role in climate forcing. This study aims to determine the role of ITAP caused by East Asian anthropogenic emissions (EAAEs) under current and future emission and climate scenarios. The contribution from EAAEs is determined using a "brute force method" in which results from simulations with and without EAAEs are compared. ITAP from East Asia is enhanced in the future due to faster wind speeds aloft and a stronger low pressure center near eastern Russia that facilitate enhanced westerly export in the free troposphere and stronger southerly transport near the surface, increased gaseous precursor emissions, and increased temperatures. As a result, the contribution of ozone (O3) generated by EAAEs to the global average O3 mixing ratio increases by ~0.8 ppb from 1.2 ppb in 2001 to 2.0 ppb in 2050. The contribution of PM2.5 generated by EAAEs to the global PM2.5 level increases by ~0.07 μg m−3 from 0.32 μg m−3 in 2001 to 0.39 μg m−3 in 2050, despite a non-homogenous response in PM2.5 resulting from cloud and radiative feedbacks. EAAEs can increase East Asian biogenic secondary organic aerosol by 10–81%, indicating that it is largely controllable. EAAEs also increase the deposition of nitrogen, black carbon, and mercury both locally and downwind, implying that they may play a role in climate feedbacks and ecosystem health of these regions. These results show that EAAEs have a large impact on global air quality and climate, especially on downwind regions. Such impacts may be enhanced under future climate and emission scenarios, demonstrating a need to synergize global pollution control and climate mitigation efforts.
Highlights
Intercontinental transport of atmospheric pollution (ITAP) is of major concern as it can offset the impact of local emission control efforts in certain regions (Jacob et al, 1999; Lin et al, 2008; Wang et al, 2009, 2012)
How will the role of ITAP change under future scenarios? What processes and factors will dominate such changes? How much BSOA can be reduced through reducing East Asian anthropogenic emissions (EAAEs)? Such information would be very useful in guiding the development of future emission control and climate mitigation strategies in a changing climate
The contributions of EAAEs to planetary boundary layer height (PBLH) over East Asia and North America are complex, but there is a general trend for decreases of 20100 m that are spatially co-located with changes in cloud droplet number concentration (CDNC) and cloud optical thickness (COT)
Summary
Intercontinental transport of atmospheric pollution (ITAP) is of major concern as it can offset the impact of local emission control efforts in certain regions (Jacob et al, 1999; Lin et al, 2008; Wang et al, 2009, 2012). Wang et al (2012) showed that dust particles transport at altitudes above 5 km It may be counter-intuitive, ITAP plays a much larger role in the boreal spring and autumn months as compared to the summer when production of pollutants such as O3 is higher (Wild and Akimoto, 2001; Shindell et al, 2008; Fiore et al, 2009; Jonson et al, 2010). These studies, along with others, were compiled into the 2010 Task Force on Hemispheric Transport of Air Pollution report (TF-HTAP) (http://www.htap.org/) These experiments found that, during spring months, the 20 % emission reductions largely from Asia can reduce the ozone level by over 1 ppb or greater at Trinidad Head, CA, at the surface and throughout the troposphere (Jonson et al, 2010). How will the role of ITAP change under future scenarios? What processes and factors will dominate such changes? How much BSOA can be reduced through reducing EAAEs? Such information would be very useful in guiding the development of future emission control and climate mitigation strategies in a changing climate
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