Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health
Tropospheric ozone is an air pollutant that substantially harms vegetation and is also strongly dependent on various vegetation-mediated processes. The interdependence between ozone and vegetation may constitute feedback mechanisms that can alter ozone concentration itself but have not been consider...
| Main Authors: | , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
Copernicus GmbH
2021
|
| Online Access: | https://hdl.handle.net/1721.1/132191 |
| _version_ | 1826211864460132352 |
|---|---|
| author | Zhou, Shan S. Tai, Amos P. K. Sun, Shihan Sadiq, Mehliyar Heald, Colette L. Geddes, Jeffrey A. |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Zhou, Shan S. Tai, Amos P. K. Sun, Shihan Sadiq, Mehliyar Heald, Colette L. Geddes, Jeffrey A. |
| author_sort | Zhou, Shan S. |
| collection | MIT |
| description | Tropospheric ozone is an air pollutant that substantially harms vegetation and is also strongly dependent on various vegetation-mediated processes. The interdependence between ozone and vegetation may constitute feedback mechanisms that can alter ozone concentration itself but have not been considered in most studies to date. In this study we examine the importance of dynamic coupling between surface ozone and leaf area index (LAI) in shaping ozone air quality and vegetation. We first implement an empirical scheme for ozone damage on vegetation in the Community Land Model (CLM) and simulate the steady-state responses of LAI to long-term exposure to a range of prescribed ozone levels (from 0 to 100 ppb). We find that most plant functional types suffer a substantial decline in LAI as ozone level increases. Based on the CLM-simulated results, we develop and implement in the GEOS-Chem chemical transport model a parameterization that computes fractional changes in monthly LAI as a function of local mean ozone levels. By forcing LAI to respond to ozone concentrations on a monthly timescale, the model simulates ozone-LAI coupling dynamically via biogeochemical processes including biogenic volatile organic compound (VOC) emissions and dry deposition, without the complication from meteorological changes. We find that ozone-induced damage on LAI can lead to changes in ozone concentrations by-1.8 to +3 ppb in boreal summer, with a corresponding ozone feedback factor of-0.1 to +0.6 that represents an overall self-amplifying effect from ozone-LAI coupling. Substantially higher simulated ozone due to strong positive feedbacks is found in most tropical forests, mainly due to the ozone-induced reductions in LAI and dry deposition velocity, whereas reduced isoprene emission plays a lesser role in these low-NOx environments. In high-NOx regions such as the eastern US, Europe, and China, however, the feedback effect is much weaker and even negative in some regions, reflecting the compensating effects of reduced dry deposition and reduced isoprene emission (which reduces ozone in high-NOx environments). In remote, low-LAI regions, including most of the Southern Hemisphere, the ozone feedback is generally slightly negative due to the reduced transport of NOx-VOC reaction products that serve as NOx reservoirs. This study represents the first step to accounting for dynamic ozone-vegetation coupling in a chemical transport model with ramifications for a more realistic joint assessment of ozone air quality and ecosystem health. |
| first_indexed | 2024-09-23T15:12:38Z |
| format | Article |
| id | mit-1721.1/132191 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T15:12:38Z |
| publishDate | 2021 |
| publisher | Copernicus GmbH |
| record_format | dspace |
| spelling | mit-1721.1/1321912021-09-21T03:13:25Z Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health Zhou, Shan S. Tai, Amos P. K. Sun, Shihan Sadiq, Mehliyar Heald, Colette L. Geddes, Jeffrey A. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Tropospheric ozone is an air pollutant that substantially harms vegetation and is also strongly dependent on various vegetation-mediated processes. The interdependence between ozone and vegetation may constitute feedback mechanisms that can alter ozone concentration itself but have not been considered in most studies to date. In this study we examine the importance of dynamic coupling between surface ozone and leaf area index (LAI) in shaping ozone air quality and vegetation. We first implement an empirical scheme for ozone damage on vegetation in the Community Land Model (CLM) and simulate the steady-state responses of LAI to long-term exposure to a range of prescribed ozone levels (from 0 to 100 ppb). We find that most plant functional types suffer a substantial decline in LAI as ozone level increases. Based on the CLM-simulated results, we develop and implement in the GEOS-Chem chemical transport model a parameterization that computes fractional changes in monthly LAI as a function of local mean ozone levels. By forcing LAI to respond to ozone concentrations on a monthly timescale, the model simulates ozone-LAI coupling dynamically via biogeochemical processes including biogenic volatile organic compound (VOC) emissions and dry deposition, without the complication from meteorological changes. We find that ozone-induced damage on LAI can lead to changes in ozone concentrations by-1.8 to +3 ppb in boreal summer, with a corresponding ozone feedback factor of-0.1 to +0.6 that represents an overall self-amplifying effect from ozone-LAI coupling. Substantially higher simulated ozone due to strong positive feedbacks is found in most tropical forests, mainly due to the ozone-induced reductions in LAI and dry deposition velocity, whereas reduced isoprene emission plays a lesser role in these low-NOx environments. In high-NOx regions such as the eastern US, Europe, and China, however, the feedback effect is much weaker and even negative in some regions, reflecting the compensating effects of reduced dry deposition and reduced isoprene emission (which reduces ozone in high-NOx environments). In remote, low-LAI regions, including most of the Southern Hemisphere, the ozone feedback is generally slightly negative due to the reduced transport of NOx-VOC reaction products that serve as NOx reservoirs. This study represents the first step to accounting for dynamic ozone-vegetation coupling in a chemical transport model with ramifications for a more realistic joint assessment of ozone air quality and ecosystem health. 2021-09-20T18:21:17Z 2021-09-20T18:21:17Z 2018-10 2018-08 2020-05-27T17:17:47Z Article http://purl.org/eprint/type/JournalArticle 1680-7324 https://hdl.handle.net/1721.1/132191 Zhou, Shan S. et al. “Coupling between Surface Ozone and Leaf Area Index in a Chemical Transport Model: Strength of Feedback and Implications for Ozone Air Quality and Vegetation Health.” Atmospheric Chemistry and Physics 18, 19 (October 2018): 14133–48. © 2018 Authors en https://doi.org/10.5194/acp-18-14133-2018 Atmospheric Chemistry and Physics Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf Copernicus GmbH Copernicus Publications |
| spellingShingle | Zhou, Shan S. Tai, Amos P. K. Sun, Shihan Sadiq, Mehliyar Heald, Colette L. Geddes, Jeffrey A. Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health |
| title | Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health |
| title_full | Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health |
| title_fullStr | Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health |
| title_full_unstemmed | Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health |
| title_short | Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health |
| title_sort | coupling between surface ozone and leaf area index in a chemical transport model strength of feedback and implications for ozone air quality and vegetation health |
| url | https://hdl.handle.net/1721.1/132191 |
| work_keys_str_mv | AT zhoushans couplingbetweensurfaceozoneandleafareaindexinachemicaltransportmodelstrengthoffeedbackandimplicationsforozoneairqualityandvegetationhealth AT taiamospk couplingbetweensurfaceozoneandleafareaindexinachemicaltransportmodelstrengthoffeedbackandimplicationsforozoneairqualityandvegetationhealth AT sunshihan couplingbetweensurfaceozoneandleafareaindexinachemicaltransportmodelstrengthoffeedbackandimplicationsforozoneairqualityandvegetationhealth AT sadiqmehliyar couplingbetweensurfaceozoneandleafareaindexinachemicaltransportmodelstrengthoffeedbackandimplicationsforozoneairqualityandvegetationhealth AT healdcolettel couplingbetweensurfaceozoneandleafareaindexinachemicaltransportmodelstrengthoffeedbackandimplicationsforozoneairqualityandvegetationhealth AT geddesjeffreya couplingbetweensurfaceozoneandleafareaindexinachemicaltransportmodelstrengthoffeedbackandimplicationsforozoneairqualityandvegetationhealth |