Unraveling impact factors for future changes in the Brewer‐Dobson circulation

Oberländer, Sophie; Langematz, Ulrike; Meul, Stefanie

doi:10.1002/jgrd.50775

Cited by 76 publications

(114 citation statements)

References 62 publications

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“…4c), when all ensemble members show trends of the same sign. The magnitude of the trend increases with decreasing pressure in agreement with earlier studies (Fels et al, 1980;Bell et al, 2010;Oberländer et al, 2013;Langematz et al, 2014). However, in the lower stratosphere (100-50 hPa) there is less confidence in the projected temperature trends across the ensemble throughout the winter.…”

Section: Trends In Arctic Stratospheric Temperaturessupporting

confidence: 88%

Future Arctic ozone recovery: the importance of chemistry and dynamics

et al. 2016

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Abstract. Future trends in Arctic springtime total column ozone, and its chemical and dynamical drivers, are assessed using a seven-member ensemble from the Met Office Unified Model with United Kingdom Chemistry and Aerosols (UM-UKCA) simulating the period 1960-2100. The Arctic mean March total column ozone increases throughout the 21st century at a rate of ∼ 11.5 DU decade −1 , and is projected to return to the 1980 level in the late 2030s. However, the integrations show that even past 2060 springtime Arctic ozone can episodically drop by ∼ 50-100 DU below the corresponding long-term ensemble mean for that period, reaching values characteristic of the near-present-day average level. Consistent with the global decline in inorganic chlorine (Cl y ) over the century, the estimated mean halogeninduced chemical ozone loss in the Arctic lower atmosphere in spring decreases by around a factor of 2 between the periods 2001-2020 and 2061-2080. However, in the presence of a cold and strong polar vortex, elevated halogen-induced ozone losses well above the corresponding long-term mean continue to occur in the simulations into the second part of the century. The ensemble shows a significant cooling trend in the Arctic winter mid-and upper stratosphere, but there is less confidence in the projected temperature trends in the lower stratosphere (100-50 hPa). This is partly due to an increase in downwelling over the Arctic polar cap in winter, which increases transport of ozone into the polar region as well as drives adiabatic warming that partly offsets the radiatively driven stratospheric cooling. However, individual winters characterised by significantly suppressed downwelling, reduced transport and anomalously low temperatures continue to occur in the future. We conclude that, despite the projected long-term recovery of Arctic ozone, the large interannual dynamical variability is expected to continue in the future, thereby facilitating episodic reductions in springtime ozone columns. Whilst our results suggest that the relative role of dynamical processes for determining Arctic springtime ozone will increase in the future, halogen chemistry will remain a smaller but non-negligible contributor for many decades to come.

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Section: Trends In Arctic Stratospheric Temperaturessupporting

confidence: 88%

Future Arctic ozone recovery: the importance of chemistry and dynamics

et al. 2016

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“…Consistent with Palmeiro et al (2014), Lin and Fu (2013) and Oberländer et al (2013), ozone recovery in the ODS experiment is associated with a weakening of the SH deep branch of the BDC during austral summer. In this model, a weakening of the NH deep branch is also simulated.…”

Section: Changes In Stesupporting

confidence: 64%

Drivers of changes in stratospheric and tropospheric ozone between year 2000 and 2100

et al. 2016

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Abstract.A stratosphere-resolving configuration of the Met Office's Unified Model (UM) with the United Kingdom Chemistry and Aerosols (UKCA) scheme is used to investigate the atmospheric response to changes in (a) greenhouse gases and climate, (b) ozone-depleting substances (ODSs) and (c) non-methane ozone precursor emissions. A suite of time-slice experiments show the separate, as well as pairwise, impacts of these perturbations between the years 2000 and 2100. Sensitivity to uncertainties in future greenhouse gases and aerosols is explored through the use of the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios.The results highlight an important role for the stratosphere in determining the annual mean tropospheric ozone response, primarily through stratosphere-troposphere exchange (STE) of ozone. Under both climate change and reductions in ODSs, increases in STE offset decreases in net chemical production and act to increase the tropospheric ozone burden. This opposes the effects of projected decreases in ozone precursors through measures to improve air quality, which act to reduce the ozone burden.The global tropospheric lifetime of ozone (τ O 3 ) does not change significantly under climate change at RCP4.5, but it decreases at RCP8.5. This opposes the increases in τ O 3 simulated under reductions in ODSs and ozone precursor emissions.The additivity of the changes in ozone is examined by comparing the sum of the responses in the single-forcing experiments to those from equivalent combined-forcing experiments. Whilst the ozone responses to most forcing combinations are found to be approximately additive, non-additive changes are found in both the stratosphere and troposphere when a large climate forcing (RCP8.5) is combined with the effects of ODSs.

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“…The strong influence of the SSTs in contrast to the relatively small influence of the vertical resolution on the tropical upward mass flux shows the strong SST effect on the stratospheric mass transport, known from earlier studies (e.g. Garny et al, 2011;Oberländer et al, 2013). The simulation RC2-oce-01 with interactively coupled ocean (Sect.…”

Section: Stratospheric Dynamicsmentioning

confidence: 60%

Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

et al. 2016

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Abstract. Three types of reference simulations, as recommended by the Chemistry-Climate Model Initiative (CCMI), have been performed with version 2.51 of the European Centre for Medium-Range Weather Forecasts -Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model: hindcast simulations , hindcast simulations with specified dynamics , i.e. nudged towards ERA-Interim reanalysis data, and combined hindcast and projection simulations . The manuscript summarizes the updates of the model system and details the different model set-ups used, including the on-line calculated diagnostics. Simulations have been performed with two different nudging setups, with and without interactive tropospheric aerosol, and with and without a coupled ocean model. Two different vertical resolutions have been applied. The on-line calculated sources and sinks of reactive species are quantified and a first evaluation of the simulation results from a global perspective is provided as a quality check of the data. The focus is on the intercomparison of the different model set-ups. The simulation data will become publicly available via CCMI and the Climate and Environmental Retrieval and Archive (CERA) database of the German Climate Computing Centre (DKRZ). This manuscript is intended to serve as an extensive reference for further analyses of the Earth System Chemistry integrated Modelling (ESCiMo) simulations.

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Unraveling impact factors for future changes in the Brewer‐Dobson circulation

Cited by 76 publications

References 62 publications

Future Arctic ozone recovery: the importance of chemistry and dynamics

Future Arctic ozone recovery: the importance of chemistry and dynamics

Drivers of changes in stratospheric and tropospheric ozone between year 2000 and 2100

Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

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