Impacts of stratospheric ozone and greenhouse gas changes on the Southern Hemisphere circulation in the CCMI models

2020 ◽  
Author(s):  
Bo-Reum Han ◽  
Jung Choi ◽  
Seok-Woo Son
Keyword(s):  
Greenhouse Gas ◽  
Southern Hemisphere ◽  
General Circulation ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Southern Annular Mode ◽  
Hadley Cell ◽  
The Past ◽  
The Future ◽  
Circulation Changes

<p> The impacts of stratospheric ozone and greenhouse gas changes on the Southern Hemisphere (SH) climate are re-visited by examining the single forcing experiments from the Chemistry-Climate Model Initiative (CCMI) project. In particular, the fixed ozone-depleting substance (ODS) runs and the fixed greenhouse gas (GHG) concentration runs are directly compared with the reference runs for both the past and future. Consistent with the previous studies, the SH-summer general circulation changes, such as changes in the jet location, Hadley cell edge, and Southern Annular Mode (SAM), show the opposite trends from the past to the future in response to the Antarctic ozone depletion and recovery. The GHG-induced circulation changes largely enhance the ozone-induced circulation changes in the past, but partly cancel them in the future. The ozone recovery-related tropospheric circulation return dates are also estimated in this study. We will further discuss the inter-model diversity among the CCMI models.</p>

scholarly journals Stratospheric Ozone Depletion: The Main Driver of Twentieth-Century Atmospheric Circulation Changes in the Southern Hemisphere

2011 ◽  
Vol 24 (3) ◽  
pp. 795-812 ◽  
Author(s):  
Lorenzo M. Polvani ◽  
Darryn W. Waugh ◽  
Gustavo J. P. Correa ◽  
Seok-Woo Son
Keyword(s):  
Twentieth Century ◽  
Greenhouse Gases ◽  
Atmospheric Circulation ◽  
Southern Hemisphere ◽  
Ozone Depletion ◽  
General Circulation ◽  
Stratospheric Ozone ◽  
Hadley Cell ◽  
Stratospheric Ozone Depletion ◽  
Circulation Changes

Abstract The importance of stratospheric ozone depletion on the atmospheric circulation of the troposphere is studied with an atmospheric general circulation model, the Community Atmospheric Model, version 3 (CAM3), for the second half of the twentieth century. In particular, the relative importance of ozone depletion is contrasted with that of increased greenhouse gases and accompanying sea surface temperature changes. By specifying ozone and greenhouse gas forcings independently, and performing long, time-slice integrations, it is shown that the impacts of ozone depletion are roughly 2–3 times larger than those associated with increased greenhouse gases, for the Southern Hemisphere tropospheric summer circulation. The formation of the ozone hole is shown to affect not only the polar tropopause and the latitudinal position of the midlatitude jet; it extends to the entire hemisphere, resulting in a broadening of the Hadley cell and a poleward extension of the subtropical dry zones. The CAM3 results are compared to and found to be in excellent agreement with those of the multimodel means of the recent Coupled Model Intercomparison Project (CMIP3) and Chemistry–Climate Model Validation (CCMVal2) simulations. This study, therefore, strongly suggests that most Southern Hemisphere tropospheric circulation changes, in austral summer over the second half of the twentieth century, have been caused by polar stratospheric ozone depletion.

scholarly journals Future changes in the stratosphere-to-troposphere ozone mass flux and the contribution from climate change and ozone recovery

2018 ◽  
Vol 18 (10) ◽  
pp. 7721-7738 ◽  
Author(s):  
Stefanie Meul ◽  
Ulrike Langematz ◽  
Philipp Kröger ◽  
Sophie Oberländer-Hayn ◽  
Patrick Jöckel
Keyword(s):  
Greenhouse Gas ◽  
Mass Flux ◽  
Tropospheric Ozone ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Ozone Production ◽  
Maximal Increase ◽  
The Future ◽  
Ozone Precursor ◽  
Ozone Depleting Substances

Abstract. Using a state-of-the-art chemistry–climate model we investigate the future change in stratosphere–troposphere exchange (STE) of ozone, the drivers of this change, as well as the future distribution of stratospheric ozone in the troposphere. Supplementary to previous work, our focus is on changes on the monthly scale. The global mean annual influx of stratospheric ozone into the troposphere is projected to increase by 53 % between the years 2000 and 2100 under the RCP8.5 greenhouse gas scenario. The change in ozone mass flux (OMF) into the troposphere is positive throughout the year with maximal increase in the summer months of the respective hemispheres. In the Northern Hemisphere (NH) this summer maximum STE increase is a result of increasing greenhouse gas (GHG) concentrations, whilst in the Southern Hemisphere(SH) it is due to equal contributions from decreasing levels of ozone depleting substances (ODS) and increasing GHG concentrations. In the SH the GHG effect is dominating in the winter months. A large ODS-related ozone increase in the SH stratosphere leads to a change in the seasonal breathing term which results in a future decrease of the OMF into the troposphere in the SH in September and October. The resulting distributions of stratospheric ozone in the troposphere differ for the GHG and ODS changes due to the following: (a) ozone input occurs at different regions for GHG- (midlatitudes) and ODS-changes (high latitudes); and (b) stratospheric ozone is more efficiently mixed towards lower tropospheric levels in the case of ODS changes, whereas tropospheric ozone loss rates grow when GHG concentrations rise. The comparison between the moderate RCP6.0 and the extreme RCP8.5 emission scenarios reveals that the annual global OMF trend is smaller in the moderate scenario, but the resulting change in the contribution of ozone with stratospheric origin (O3s) to ozone in the troposphere is of comparable magnitude in both scenarios. This is due to the larger tropospheric ozone precursor emissions and hence ozone production in the RCP8.5 scenario.

scholarly journals Future changes in the stratosphere-to-troposphere ozone mass flux and the contribution from climate change and ozone recovery

2018 ◽  
Author(s):  
Stefanie Meul ◽  
Ulrike Langematz ◽  
Philipp Kröger ◽  
Sophie Oberländer-Hayn ◽  
Patrick Jöckel
Keyword(s):  
Greenhouse Gas ◽  
Mass Flux ◽  
Tropospheric Ozone ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Model Simulations ◽  
The Future ◽  
Ozone Trend ◽  
Ozone Depleting Substances ◽  
Troposphere Ozone

Abstract. Model simulations consistently project an increase in the stratosphere-troposphere exchange (STE) of ozone in the future. Both, a strengthened circulation and ozone recovery in the stratosphere contribute to the increased mass flux. In our study, we investigate with a state-of-the-art chemistry-climate model the drivers of future STE change as well as the change in the distribution of stratospheric ozone in the troposphere. Our focus is on the investigation of the changes on the monthly scale. The global mean influx of stratospheric ozone into the troposphere is projected to increase between the years 2000 and 2100 by 53 % under the RCP8.5 greenhouse gas scenario. We find the largest increase of STE in the NH in June due to increasing greenhouse gas (GHG) concentrations. In the SH the GHG effect is dominating in the winter months, while decreasing levels of ozone depleting substances (ODS) and increasing GHG concentrations contribute nearly equally to the increase in SH summer. A large ODS-related ozone increase in the southern hemisphere (SH) stratosphere leads to a change in the seasonal breathing term which results in a future decrease of the ozone mass flux into the troposphere in the SH in September and October. We find that the GHG effect on the STE change is due to circulation and stratospheric ozone changes, whereas the ODS effect is dominated by the increased ozone abundance in the stratosphere. The resulting distributions of stratospheric ozone in the troposphere for the GHG and ODS changes differ because of the different regions of ozone input (GHG: midlatitudes; ODS: high latitudes) and the larger increase of tropospheric ozone loss rates due to GHG increase. Thus, the model simulations indicate that stratospheric ozone is more efficiently mixed to lower levels if only ODS levels are changed. The increase of the stratospheric ozone column in the troposphere explains more than 80 % of the tropospheric ozone trend in NH spring and in the SH except for the summer months. The importance of the future stratospheric ozone contribution to tropospheric ozone burdens therefore depends on the season.

scholarly journals Radiative and dynamical contributions to past and future Arctic stratospheric temperature trends

2013 ◽  
Vol 13 (3) ◽  
pp. 6707-6728
Author(s):  
P. Bohlinger ◽  
B.-M. Sinnhuber ◽  
R. Ruhnke ◽  
O. Kirner
Keyword(s):  
Planetary Wave ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Warming Trend ◽  
Wave Activity ◽  
The Arctic ◽  
The Past ◽  
Stratospheric Temperature ◽  
The Future ◽  
Cooling Trend

Abstract. Arctic stratospheric ozone depletion is closely linked to the occurrence of low stratospheric temperatures. There are indications that cold winters in the Arctic stratosphere have been getting colder, raising the question if and to what extent a cooling of the Arctic stratosphere may continue into the future. We use meteorological re-analyses from ERA-Interim for the past 32 yr together with calculations of the chemistry-climate model EMAC and CCM models from the CCMVal project to infer radiative and dynamical contributions to long-term Arctic stratospheric temperature changes. For the past three decades ERA-Interim shows a warming trend in winter and cooling trend in spring and summer. Changes in winter and spring are caused by a corresponding change of planetary wave activity with increases in winter and decreases in spring. During winter the increase of planetary wave activity is counteracted by a radiatively induced cooling. Stratospheric radiatively induced cooling is detected throughout all seasons being highly significant in spring and summer. This means that for a given dynamical situation, in ERA-Interim the annual mean temperature of the Arctic lower stratosphere has been cooling by −0.41 ± 0.11 K decade−1 at 50 hPa over the past 32 yr. Calculations with state-of-the-art models from CCMVal and the EMAC model confirm the radiatively induced cooling for the past decades, but underestimate the amount of radiatively induced cooling deduced from ERA-Interim. EMAC predicts a continued annual radiatively induced cooling for the coming decades (2001–2049) of −0.15 ± 0.06 K decade−1 where the projected increase of CO2 accounts for about 2/3 of the cooling effect. Expected decrease of stratospheric halogen loading and resulting ozone recovery in the future counteracts the cooling tendency due to increasing greenhouse gas concentrations and leads to a reduced future cooling trend compared to the past. CCMVal multi-model mean predicts a future annual mean radiatively induced cooling of −0.10 ± 0.02 K decade−1 which is also smaller in the future than in the past.

Aerosol versus greenhouse gas impacts on Southern Hemisphere general circulation changes

2018 ◽  
Vol 52 (7-8) ◽  
pp. 4127-4142 ◽  
Author(s):  
Jung Choi ◽  
Seok-Woo Son ◽  
Rokjin J. Park
Keyword(s):  
Greenhouse Gas ◽  
Southern Hemisphere ◽  
General Circulation ◽  
Circulation Changes

A pause in Southern Hemisphere circulation trends due to the Montreal Protocol

2021 ◽  
Author(s):  
Antara Banerjee ◽  
John C. Fyfe ◽  
Lorenzo M. Polvani ◽  
Darryn Waugh ◽  
Kai-Lan Chang
Keyword(s):  
Southern Hemisphere ◽  
Ocean Circulation ◽  
Stratospheric Ozone ◽  
Southern Annular Mode ◽  
Montreal Protocol ◽  
Hadley Cell ◽  
Positive Trend ◽  
Earth System ◽  
Near Surface ◽  
The Earth

<p>Observations show robust near-surface trends in Southern Hemisphere tropospheric circulation towards the end of the twentieth century, including a poleward shift in the mid-latitude jet, a positive trend in the Southern Annular Mode and an expansion of the Hadley cell. It has been established that these trends were driven by ozone depletion in the Antarctic stratosphere due to emissions of ozone-depleting substances. Here we show that these widely reported circulation trends paused, or slightly reversed, around the year 2000. Using a pattern-based detection and attribution analysis of atmospheric zonal wind, we show that the pause in circulation trends is forced by human activities, and has not occurred owing only to internal or natural variability of the climate system. Furthermore, we demonstrate that stratospheric ozone recovery, resulting from the Montreal Protocol, is the key driver of the pause. Because pre-2000 circulation trends have affected precipitation, and potentially ocean circulation and salinity, we anticipate that a pause in these trends will have wider impacts on the Earth system. Signatures of the effects of the Montreal Protocol and the associated stratospheric ozone recovery might therefore manifest, or have already manifested, in other aspects of the Earth system.</p>

Modeling Obliquity and CO2 Effects on Southern Hemisphere Climate during the Past 408 ka*

2014 ◽  
Vol 27 (5) ◽  
pp. 1863-1875 ◽  
Author(s):  
Axel Timmermann ◽  
Tobias Friedrich ◽  
Oliver Elison Timm ◽  
Megumi O. Chikamoto ◽  
Ayako Abe-Ouchi ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Heat Transport ◽  
Southern Hemisphere ◽  
Radiative Forcing ◽  
General Circulation ◽  
Storm Tracks ◽  
Transient Model ◽  
Middle Troposphere ◽  
The Past ◽  
Southern Hemisphere Westerlies

Abstract The effect of obliquity and CO2 changes on Southern Hemispheric climate is studied with a series of numerical modeling experiments. Using the Earth system model of intermediate complexity Loch–VECODE–ECBilt–CLIO–Agism Model (LOVECLIM) and a coupled general circulation model [Model for Interdisciplinary Research on Climate (MIROC)], it is shown in time-slice simulations that phases of low obliquity enhance the meridional extratropical temperature gradient, increase the atmospheric baroclinicity, and intensify the lower and middle troposphere Southern Hemisphere westerlies and storm tracks. Furthermore, a transient model simulation is conducted with LOVECLIM that covers the greenhouse gas, ice sheet, and orbital forcing history of the past 408 ka. This simulation reproduces reconstructed glacial–interglacial variations in temperature and sea ice qualitatively well and shows that the meridional heat transport associated with the orbitally paced modulation of middle troposphere westerlies and storm tracks partly offsets the effects of the direct shortwave obliquity forcing over Antarctica, thereby reinforcing the high correlation between CO2 radiative forcing and Antarctic temperature. The overall timing of temperature changes in Antarctica is hence determined by a balance of shortwave obliquity forcing, atmospheric heat transport changes, and greenhouse gas forcing. A shorter 130-ka transient model experiment with constant CO2 concentrations further demonstrates that surface Southern Hemisphere westerlies are primarily modulated by the obliquity cycle rather than by the CO2 radiative forcing.

scholarly journals Polar Middle Atmospheric Responses to Medium Energy Electron (MEE) Precipitation Using Numerical Model Simulations

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 133
Author(s):  
Ji-Hee Lee ◽  
Geonhwa Jee ◽  
Young-Sil Kwak ◽  
Heejin Hwang ◽  
Annika Seppälä ◽  
...  
Keyword(s):  
Climate Model ◽  
Middle Atmosphere ◽  
Meridional Circulation ◽  
Stratospheric Ozone ◽  
High Energy ◽  
Chemical Changes ◽  
Temperature Changes ◽  
Mesospheric Temperature ◽  
High Energy Electrons ◽  
Circulation Changes

Energetic particle precipitation (EPP) is known to be an important source of chemical changes in the polar middle atmosphere in winter. Recent modeling studies further suggest that chemical changes induced by EPP can also cause dynamic changes in the middle atmosphere. In this study, we investigated the atmospheric responses to the precipitation of medium-to-high energy electrons (MEEs) over the period 2005–2013 using the Specific Dynamics Whole Atmosphere Community Climate Model (SD-WACCM). Our results show that the MEE precipitation significantly increases the amounts of NOx and HOx, resulting in mesospheric and stratospheric ozone losses by up to 60% and 25% respectively during polar winter. The MEE-induced ozone loss generally increases the temperature in the lower mesosphere but decreases the temperature in the upper mesosphere with large year-to-year variability, not only by radiative effects but also by adiabatic effects. The adiabatic effects by meridional circulation changes may be dominant for the mesospheric temperature changes. In particular, the meridional circulation changes occasionally act in opposite ways to vary the temperature in terms of height variations, especially at around the solar minimum period with low geomagnetic activity, which cancels out the temperature changes to make the average small in the polar mesosphere for the 9-year period.

scholarly journals Future Changes in the Ozone Quasi-Biennial Oscillation with Increasing GHGs and Ozone Recovery in CCMI Simulations

2017 ◽  
Vol 30 (17) ◽  
pp. 6977-6997 ◽  
Author(s):  
Hiroaki Naoe ◽  
Makoto Deushi ◽  
Kohei Yoshida ◽  
Kiyotaka Shibata
Keyword(s):  
Zonal Wind ◽  
Climate Model ◽  
Vertical Shear ◽  
Quasi Biennial Oscillation ◽  
The Past ◽  
Meteorological Research Institute ◽  
Climate Simulations ◽  
The Future ◽  
Ozone Depleting Substances ◽  
Biennial Oscillation

The future quasi-biennial oscillation (QBO) in ozone in the equatorial stratosphere is examined by analyzing transient climate simulations due to increasing greenhouse gases (GHGs) and decreasing ozone-depleting substances under the auspices of the Chemistry–Climate Model Initiative. The future (1960–2100) and historical (1979–2010) simulations are conducted with the Meteorological Research Institute Earth System Model. Three climate periods, 1960–85 (past), 1990–2020 (present), and 2040–70 (future) are selected, corresponding to the periods before, during, and after ozone depletion. The future ozone QBO is characterized by increases in amplitude by 15%–30% at 5–10 hPa and decreases by 20%–30% at 40 hPa, compared with the past and present climates; the future and present ozone QBOs increase in amplitude by up to 60% at 70 hPa, compared with the past climate. The increased amplitude at 5–10 hPa suggests that the temperature-dependent photochemistry plays an important role in the enhanced future ozone QBO. The weakening of vertical shear in the zonal wind QBO is responsible for the decreased amplitude at 40 hPa in the future ozone QBO. An interesting finding is that the weakened zonal wind QBO in the lowermost tropical stratosphere is accompanied by amplified QBOs in ozone, vertical velocity, and temperature. Further study is needed to elucidate the causality of amplification about the ozone and temperature QBOs under climate change in conditions of zonal wind QBO weakening.

scholarly journals Chemical and climatic drivers of radiative forcing due to changes in stratospheric and tropospheric ozone over the 21<sup>st</sup> century

2017 ◽  
Author(s):  
Antara Banerjee ◽  
Amanda C. Maycock ◽  
John A. Pyle
Keyword(s):  
Greenhouse Gas ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Radiative Forcings ◽  
Climatic Drivers ◽  
Ozone Precursor ◽  
Ozone Depleting Substances ◽  
Projected Changes

Abstract. The ozone radiative forcings (RFs) resulting from projected changes in climate, ozone-depleting substances (ODSs), non-methane ozone precursor emissions and methane between the years 2000 and 2100 are calculated using simulations from the UM-UKCA chemistry-climate model. Projected measures to improve air-quality through reductions in tropospheric ozone precursor emissions present a co-benefit for climate, with a net global mean ozone RF of −0.09 Wm−2. This is opposed by a positive ozone RF of 0.07 Wm−2 due to future decreases in ODSs, which is mainly driven by an increase in tropospheric ozone through stratosphere-to-troposphere exchange. An increase in methane abundance by more than a factor of two (as projected by the RCP8.5 scenario) is found to drive an ozone RF of 0.19 Wm−2, which would greatly outweigh the climate benefits of tropospheric non-methane ozone precursor reductions. A third of the ozone RF due to the projected increase in methane results from increases in stratospheric ozone. The sign of the ozone RF due to future changes in climate (including the radiative effects of greenhouse gas concentrations, sea surface temperatures and sea ice changes) is shown to be dependent on the greenhouse gas emissions pathway, with a positive RF (0.06 Wm−2) for RCP4.5 and a negative RF (−0.07 Wm−2) for the RCP8.5 scenario. This dependence arises from differences in the contribution to RF from stratospheric ozone changes.

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