Ozone Continues to Increase in East Asia Despite Decreasing NO<sub>2</sub>: Causes and Abatements
Space-borne ozone (O<sub>3</sub>) measurements have indicated consistent positive trends across the entire Asia–Pacific region despite the considerable reduction of NO<sub>x</sub> since 2000s. The rate of increase in O<sub>3</sub> derived from lower free troposphe...
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| Language: | English |
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MDPI AG
2021-06-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/13/11/2177 |
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| author | Hyo-Jung Lee Lim-Seok Chang Daniel A. Jaffe Juseon Bak Xiong Liu Gonzalo González Abad Hyun-Young Jo Yu-Jin Jo Jae-Bum Lee Cheol-Hee Kim |
| author_facet | Hyo-Jung Lee Lim-Seok Chang Daniel A. Jaffe Juseon Bak Xiong Liu Gonzalo González Abad Hyun-Young Jo Yu-Jin Jo Jae-Bum Lee Cheol-Hee Kim |
| author_sort | Hyo-Jung Lee |
| collection | DOAJ |
| description | Space-borne ozone (O<sub>3</sub>) measurements have indicated consistent positive trends across the entire Asia–Pacific region despite the considerable reduction of NO<sub>x</sub> since 2000s. The rate of increase in O<sub>3</sub> derived from lower free tropospheric column measurements was observed to be 0.21 ± 0.05 DU/decade during 2005–2018. Our space-borne-based diagnosis of the nonlinear photochemical formation regimes, NO<sub>x</sub>-limited and NO<sub>x</sub>-saturated, show that O<sub>3</sub> chemistry is undergoing a transitional process to the NO<sub>x</sub>-limited regime throughout most of the Asian region. Nevertheless, NO<sub>x</sub>-saturated conditions persist at present in and over eight major megacities. These NO<sub>x</sub>-saturated conditions in megacities contribute to the increased O<sub>3</sub> due to NO<sub>x</sub> reduction, which could also affect the enhanced O<sub>3</sub> concentrations throughout the Asia–Pacific region via long-range transport. This indicates that VOC limits along with NO<sub>x</sub> reductions are needed in megacities in the short term to reduce O<sub>3</sub> levels. Moreover, NO<sub>x</sub> saturation in major megacities will continue until 2025, according to the forecast emission scenarios from the Intergovernmental Panel on Climate Change (IPCC). These scenarios gradually shift nearly all cities to the NO<sub>x</sub>-limited regime by 2050 with the exception of few cities under IPCC RCP8.5. Thus, continued reductions in NO<sub>x</sub> will be a key factor in reducing O<sub>3</sub> in the long term. |
| first_indexed | 2024-03-10T10:46:12Z |
| format | Article |
| id | doaj.art-c00eb0234f40447ba5ed108798b2ff78 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T10:46:12Z |
| publishDate | 2021-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-c00eb0234f40447ba5ed108798b2ff782023-11-21T22:35:47ZengMDPI AGRemote Sensing2072-42922021-06-011311217710.3390/rs13112177Ozone Continues to Increase in East Asia Despite Decreasing NO<sub>2</sub>: Causes and AbatementsHyo-Jung Lee0Lim-Seok Chang1Daniel A. Jaffe2Juseon Bak3Xiong Liu4Gonzalo González Abad5Hyun-Young Jo6Yu-Jin Jo7Jae-Bum Lee8Cheol-Hee Kim9Institute of Environmental Studies, Pusan National University, Busan 46241, KoreaClimate & Air Quality Research Department, National Institute of Environmental Research, Incheon 22689, KoreaSchool of STEM, University of Washington Bothell, Bothell, WA 98011, USAInstitute of Environmental Studies, Pusan National University, Busan 46241, KoreaHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USAHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USAInstitute of Environmental Studies, Pusan National University, Busan 46241, KoreaDepartment of Atmospheric Sciences, Pusan National University, Busan 46241, KoreaClimate & Air Quality Research Department, National Institute of Environmental Research, Incheon 22689, KoreaInstitute of Environmental Studies, Pusan National University, Busan 46241, KoreaSpace-borne ozone (O<sub>3</sub>) measurements have indicated consistent positive trends across the entire Asia–Pacific region despite the considerable reduction of NO<sub>x</sub> since 2000s. The rate of increase in O<sub>3</sub> derived from lower free tropospheric column measurements was observed to be 0.21 ± 0.05 DU/decade during 2005–2018. Our space-borne-based diagnosis of the nonlinear photochemical formation regimes, NO<sub>x</sub>-limited and NO<sub>x</sub>-saturated, show that O<sub>3</sub> chemistry is undergoing a transitional process to the NO<sub>x</sub>-limited regime throughout most of the Asian region. Nevertheless, NO<sub>x</sub>-saturated conditions persist at present in and over eight major megacities. These NO<sub>x</sub>-saturated conditions in megacities contribute to the increased O<sub>3</sub> due to NO<sub>x</sub> reduction, which could also affect the enhanced O<sub>3</sub> concentrations throughout the Asia–Pacific region via long-range transport. This indicates that VOC limits along with NO<sub>x</sub> reductions are needed in megacities in the short term to reduce O<sub>3</sub> levels. Moreover, NO<sub>x</sub> saturation in major megacities will continue until 2025, according to the forecast emission scenarios from the Intergovernmental Panel on Climate Change (IPCC). These scenarios gradually shift nearly all cities to the NO<sub>x</sub>-limited regime by 2050 with the exception of few cities under IPCC RCP8.5. Thus, continued reductions in NO<sub>x</sub> will be a key factor in reducing O<sub>3</sub> in the long term.https://www.mdpi.com/2072-4292/13/11/2177tropospheric ozone columnformaldehyde-to-nitrogen dioxide ratio (FNR)tropospheric NO<sub>2</sub> columntropospheric HCHO columnOMI measurements |
| spellingShingle | Hyo-Jung Lee Lim-Seok Chang Daniel A. Jaffe Juseon Bak Xiong Liu Gonzalo González Abad Hyun-Young Jo Yu-Jin Jo Jae-Bum Lee Cheol-Hee Kim Ozone Continues to Increase in East Asia Despite Decreasing NO<sub>2</sub>: Causes and Abatements Remote Sensing tropospheric ozone column formaldehyde-to-nitrogen dioxide ratio (FNR) tropospheric NO<sub>2</sub> column tropospheric HCHO column OMI measurements |
| title | Ozone Continues to Increase in East Asia Despite Decreasing NO<sub>2</sub>: Causes and Abatements |
| title_full | Ozone Continues to Increase in East Asia Despite Decreasing NO<sub>2</sub>: Causes and Abatements |
| title_fullStr | Ozone Continues to Increase in East Asia Despite Decreasing NO<sub>2</sub>: Causes and Abatements |
| title_full_unstemmed | Ozone Continues to Increase in East Asia Despite Decreasing NO<sub>2</sub>: Causes and Abatements |
| title_short | Ozone Continues to Increase in East Asia Despite Decreasing NO<sub>2</sub>: Causes and Abatements |
| title_sort | ozone continues to increase in east asia despite decreasing no sub 2 sub causes and abatements |
| topic | tropospheric ozone column formaldehyde-to-nitrogen dioxide ratio (FNR) tropospheric NO<sub>2</sub> column tropospheric HCHO column OMI measurements |
| url | https://www.mdpi.com/2072-4292/13/11/2177 |
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