Role of the stratospheric chemistry–climate interactions in the hot climate conditions of the Eocene
<p>The stratospheric ozone layer plays a key role in atmospheric thermal structure and circulation. Although stratospheric ozone distribution is sensitive to changes in trace gases concentrations and climate, the modifications of stratospheric ozone are not usually considered in climate studie...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-07-01
|
| Series: | Climate of the Past |
| Online Access: | https://www.clim-past.net/15/1187/2019/cp-15-1187-2019.pdf |
| _version_ | 1811323997379362816 |
|---|---|
| author | S. Szopa R. Thiéblemont S. Bekki S. Botsyun S. Botsyun P. Sepulchre |
| author_facet | S. Szopa R. Thiéblemont S. Bekki S. Botsyun S. Botsyun P. Sepulchre |
| author_sort | S. Szopa |
| collection | DOAJ |
| description | <p>The stratospheric ozone layer plays a key role in atmospheric thermal
structure and circulation. Although stratospheric ozone distribution is
sensitive to changes in trace gases concentrations and climate, the
modifications of stratospheric ozone are not usually considered in climate
studies at geological timescales. Here, we evaluate the potential role of
stratospheric ozone chemistry in the case of the Eocene hot conditions.
Using a chemistry–climate model, we show that the structure of the ozone
layer is significantly different under these conditions (<span class="inline-formula">4×CO<sub>2</sub></span> climate
and high concentrations of tropospheric <span class="inline-formula">N<sub>2</sub>O</span> and <span class="inline-formula">CH<sub>4</sub></span>). The total
column ozone (TCO) remains more or less unchanged in the tropics whereas it
is found to be enhanced at mid- and high latitudes. These ozone changes are
related to the stratospheric cooling and an acceleration of stratospheric
Brewer–Dobson circulation simulated under Eocene climate. As a consequence,
the meridional distribution of the TCO appears to be modified, showing
particularly pronounced midlatitude maxima and a steeper negative poleward
gradient from these maxima. These anomalies are consistent with changes in
the seasonal evolution of the polar vortex during winter, especially in the
Northern Hemisphere, found to be mainly driven by seasonal changes in
planetary wave activity and stratospheric wave-drag. Compared to a
preindustrial atmospheric composition, the changes in local ozone
concentration reach up to 40 % for zonal annual mean and affect
temperature by a few kelvins in the middle stratosphere.</p>
<p>As inter-model differences in simulating deep-past temperatures are
quite high, the consideration of atmospheric chemistry, which is
computationally demanding in Earth system models, may seem superfluous.
However, our results suggest that using stratospheric ozone calculated by
the model (and hence more physically consistent with Eocene conditions)
instead of the commonly specified preindustrial ozone distribution could
change the simulated global surface air temperature by as much as 14 %. This
error is of the same order as the effect of non-<span class="inline-formula">CO<sub>2</sub></span> boundary conditions
(topography, bathymetry, solar constant and vegetation). Moreover, the
results highlight the sensitivity of stratospheric ozone to hot climate
conditions. Since the climate sensitivity to stratospheric ozone feedback
largely differs between models, it must be better constrained not only for
deep-past conditions but also for future climates.</p> |
| first_indexed | 2024-04-13T14:06:21Z |
| format | Article |
| id | doaj.art-46226d81f4914e82ab3962c1c9e032ad |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-04-13T14:06:21Z |
| publishDate | 2019-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-46226d81f4914e82ab3962c1c9e032ad2022-12-22T02:43:54ZengCopernicus PublicationsClimate of the Past1814-93241814-93322019-07-01151187120310.5194/cp-15-1187-2019Role of the stratospheric chemistry–climate interactions in the hot climate conditions of the EoceneS. Szopa0R. Thiéblemont1S. Bekki2S. Botsyun3S. Botsyun4P. Sepulchre5Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, FranceLaboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, FranceLaboratoire Atmosphère, Milieux, Observations Spatiales, Institut Pierre Simon Laplace, LATMOS/IPSL, CNRS-UVSQ-Sorbonne Université, Guyancourt and Paris, FranceLaboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, Francenow at: Department of Geosciences, University of Tübingen, Tübingen, GermanyLaboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France<p>The stratospheric ozone layer plays a key role in atmospheric thermal structure and circulation. Although stratospheric ozone distribution is sensitive to changes in trace gases concentrations and climate, the modifications of stratospheric ozone are not usually considered in climate studies at geological timescales. Here, we evaluate the potential role of stratospheric ozone chemistry in the case of the Eocene hot conditions. Using a chemistry–climate model, we show that the structure of the ozone layer is significantly different under these conditions (<span class="inline-formula">4×CO<sub>2</sub></span> climate and high concentrations of tropospheric <span class="inline-formula">N<sub>2</sub>O</span> and <span class="inline-formula">CH<sub>4</sub></span>). The total column ozone (TCO) remains more or less unchanged in the tropics whereas it is found to be enhanced at mid- and high latitudes. These ozone changes are related to the stratospheric cooling and an acceleration of stratospheric Brewer–Dobson circulation simulated under Eocene climate. As a consequence, the meridional distribution of the TCO appears to be modified, showing particularly pronounced midlatitude maxima and a steeper negative poleward gradient from these maxima. These anomalies are consistent with changes in the seasonal evolution of the polar vortex during winter, especially in the Northern Hemisphere, found to be mainly driven by seasonal changes in planetary wave activity and stratospheric wave-drag. Compared to a preindustrial atmospheric composition, the changes in local ozone concentration reach up to 40 % for zonal annual mean and affect temperature by a few kelvins in the middle stratosphere.</p> <p>As inter-model differences in simulating deep-past temperatures are quite high, the consideration of atmospheric chemistry, which is computationally demanding in Earth system models, may seem superfluous. However, our results suggest that using stratospheric ozone calculated by the model (and hence more physically consistent with Eocene conditions) instead of the commonly specified preindustrial ozone distribution could change the simulated global surface air temperature by as much as 14 %. This error is of the same order as the effect of non-<span class="inline-formula">CO<sub>2</sub></span> boundary conditions (topography, bathymetry, solar constant and vegetation). Moreover, the results highlight the sensitivity of stratospheric ozone to hot climate conditions. Since the climate sensitivity to stratospheric ozone feedback largely differs between models, it must be better constrained not only for deep-past conditions but also for future climates.</p>https://www.clim-past.net/15/1187/2019/cp-15-1187-2019.pdf |
| spellingShingle | S. Szopa R. Thiéblemont S. Bekki S. Botsyun S. Botsyun P. Sepulchre Role of the stratospheric chemistry–climate interactions in the hot climate conditions of the Eocene Climate of the Past |
| title | Role of the stratospheric chemistry–climate interactions in the hot climate conditions of the Eocene |
| title_full | Role of the stratospheric chemistry–climate interactions in the hot climate conditions of the Eocene |
| title_fullStr | Role of the stratospheric chemistry–climate interactions in the hot climate conditions of the Eocene |
| title_full_unstemmed | Role of the stratospheric chemistry–climate interactions in the hot climate conditions of the Eocene |
| title_short | Role of the stratospheric chemistry–climate interactions in the hot climate conditions of the Eocene |
| title_sort | role of the stratospheric chemistry climate interactions in the hot climate conditions of the eocene |
| url | https://www.clim-past.net/15/1187/2019/cp-15-1187-2019.pdf |
| work_keys_str_mv | AT sszopa roleofthestratosphericchemistryclimateinteractionsinthehotclimateconditionsoftheeocene AT rthieblemont roleofthestratosphericchemistryclimateinteractionsinthehotclimateconditionsoftheeocene AT sbekki roleofthestratosphericchemistryclimateinteractionsinthehotclimateconditionsoftheeocene AT sbotsyun roleofthestratosphericchemistryclimateinteractionsinthehotclimateconditionsoftheeocene AT sbotsyun roleofthestratosphericchemistryclimateinteractionsinthehotclimateconditionsoftheeocene AT psepulchre roleofthestratosphericchemistryclimateinteractionsinthehotclimateconditionsoftheeocene |