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| Home > Publications database > Ozone pollution in China and India from a global perspective: present-day status and interannual variability drivers |
| Home > Publications database > Ozone pollution in China and India from a global perspective: present-day status and interannual variability drivers |
| Poster (Plenary/Keynote) | FZJ-2018-07551 |
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2018
Abstract: The equatorward redistribution of anthropogenic emissions to developing regions such as China and India since 1980s has potentially shifted the worldwide air pollution hotspots to these regions. However, our current understanding of ozone pollution in these populous regions and induced health and vegetation exposure is rather limited because of the scarcity of ozone observations. We will present studies on the present-day distribution and interannual variability of tropospheric ozone in China and India, using national and global surface ozone monitoring networks and satellite observations combined with the GEOS-Chem chemical transport model. We first show that China now likely faces the severest surface ozone pollution over the world. The present surface ozone pollution over China is comparable to or even higher than the 1980 levels in the US. The summertime 4th highest daily maximum 8-h average ozone (86.0 ppbv) in Chinese cities is about 25% higher than those in present-day Europe and US urban regions. The induced health and vegetation ozone exposure as evaluated by various exposure metrics are also significantly higher in China. We find a significant increase of surface ozone in China in 2016-2017 compared to 2013-2014, even though the nitrogen dioxide (NO2) and carbon monoxide (CO) concentrations have decreased. Lower tropospheric ozone (surface-600 hPa) over India as seen from satellite observations peaks in May (54.1 ppbv) and reaches the lowest concentrations (40.5 ppbv) in August, reflecting strong influences from the South Asian summer monsoon (SASM). We find that summertime ozone concentrations in India over 1990-2010 are strongly correlated with the SASM strength (r=-0.72). Lower ozone concentrations are found in stronger monsoon years mainly due to less ozone net chemical production. Model simulations estimate a significant increasing annual trend of 0.19±0.07 ppbv year-1 (p-value<0.01) in Indian lower tropospheric ozone over 1990–2010, which are mainly driven by increases in anthropogenic emissions (more than 90%) with a small contribution from global methane increases. Our results illustrate the severe and deteriorating ozone pollution in both populous regions that requires attention.
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