The Brewer‐Dobson circulation

Butchart, Neal

doi:10.1002/2013rg000448

Cited by 586 publications

(725 citation statements)

References 219 publications

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“…Overall, this should have consequences for the transport of species like ozone, which are not calculated in this study. However, the streamlines do not represent wave-induced meridional mixing (Butchart, 2014). We show in Sect.…”

Section: Effects On the Brewer-dobson Circulationmentioning

confidence: 93%

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Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

2017

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Abstract. The injection of sulfur dioxide (SO 2 ) into the stratosphere to form an artificial stratospheric aerosol layer is discussed as an option for solar radiation management. Sulfate aerosol scatters solar radiation and absorbs infrared radiation, which warms the stratospheric sulfur layer. Simulations with the general circulation model ECHAM5-HAM, including aerosol microphysics, show consequences of this warming, including changes of the quasi-biennial oscillation (QBO) in the tropics. The QBO slows down after an injection of 4 Tg(S) yr −1 and completely shuts down after an injection of 8 Tg(S) yr −1 . Transport of species in the tropics and subtropics depends on the phase of the QBO. Consequently, the heated aerosol layer not only impacts the oscillation of the QBO but also the meridional transport of the sulfate aerosols. The stronger the injection, the stronger the heating and the simulated impact on the QBO and equatorial wind systems. With increasing injection rate the velocity of the equatorial jet streams increases, and the less sulfate is transported out of the tropics. This reduces the global distribution of sulfate and decreases the radiative forcing efficiency of the aerosol layer by 10 to 14 % compared to simulations with low vertical resolution and without generated QBO. Increasing the height of the injection increases the radiative forcing only for injection rates below 10 Tg(S) yr −1 (8-18 %), a much smaller value than the 50 % calculated previously. Stronger injection rates at higher levels even result in smaller forcing than the injections at lower levels.

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Section: Effects On the Brewer-dobson Circulationmentioning

confidence: 93%

“…given in Haynes and Shuckburgh (2000). Butchart (2014) provides an overview of the stratospheric dynamic processes described above, as well as related references.…”

Section: Circulation In the Stratospherementioning

confidence: 99%

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

2017

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“…Furthermore, whereas the maximum SH tropospheric 14 C increase during the bomb spike was just 70% of mid-latitude NH values (Manning et al 1990), reflecting the fact that close to 100% of the input was generated within the NH, the M12 amplitude in the kauri is~90% of the mean of the NH stations ( Table 1), indicating that significant 14 C production occurred in both hemispheres. -17.3 ± 1.8 -6.2 ± 1.4 11.1 ± 2.3 California (sequoia) 36°N -17.6 ± 0.9 -2.1 ± 1.0 15.5 ± 1.4 New Zealand 36°S -23.8 ± 0.8 -9.7 ± 0.7 14.1 ± 1.0 *Average of data from two laboratories (Usoskin et al 2013) Large-scale stratospheric air transport is dominated by the so-called Brewer-Dobson circulation (Butchart 2014) characterized by injection of tropospheric air into the stratosphere in the tropics and subsequently by movement towards the winter pole and subsidence at high latitudes, driven primarily by seasonally varying large-scale eddy motions that act to reduce the mean zonal velocity of air parcels and thus induce a poleward drift (Holton et al 1995). Descending air in the winter polar vortex carrying a high burden of stratospheric tracers is released near the tropopause when the vortex breaks up in the spring, and extratropical injection of stratospheric air into the troposphere peaks in mid-to-late summer (Stohl et al 2003).…”

Section: M12 Peak Analysismentioning

confidence: 99%

Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC

et al. 2017

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ABSTRACT. Since the AD 775 and AD 994 Δ 14 C peak (henceforth M12) was first measured by Miyake et al. (2012Miyake et al. ( , 2013, several possible production mechanisms for these spike have been suggested, but the work of Mekhaldi et al. (2015) shows that a very soft energy spectrum was involved, implying that a strong solar energetic particle (SEP) event (or series of events) was responsible. Here we present Δ 14 C values from AD 721-820 Sequoiadendron giganteum annual tree-ring samples from Sequoia National Park in California, USA, together with Δ 14 C in German oak from 650-670 BC. The AD 721-820 measurements confirm that a sharp Δ 14 C peak exists at AD 775, with a peak height of approximately 15‰ and show that this spike was preceded by several decades of rapidly decreasing Δ 14 C. A sharp peak is also present at 660 BC, with a peak height of about 10‰, and published data ) indicate that it too was preceded by a multi-decadal Δ 14 C decrease, suggesting that solar activity was very strong just prior to both Δ 14 C peaks and may be causally related. During periods of strong solar activity there is increased probability for coronal mass ejection (CME) events that can subject the Earth's atmosphere to high fluencies of solar energetic particles (SEPs). Periods of high solar activity (such as one in October-November 2003) can also often include many large, fast CMEs increasing the probability of geomagnetic storms. In this paper we suggest that the combination of large SEP events and elevated geomagnetic activity can lead to enhanced production of 14 C and other cosmogenic isotopes by increasing the area of the atmosphere that is irradiated by high solar energetic particles.

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“…However, the strengthening or weakening of the BDC is still under debate (Butchart, 2014, and references therein). Results from observations indicate that the BDC may have slightly decelerated (Engel et al, 2009;Stiller et al, 2012), while estimates from a number of chemistry-climate models (CCMs) show in contrast a strengthening of the BDC (Butchart et al, 2010;Li et al, 2008;Butchart, 2014). The reason for the discrepancy between observed and modelled BDC changes, as well as the mechanisms of the BDC response to climate change, is still under discussion (Oberländer et al, 2013;Shepherd and McLandress, 2011).…”

Section: W Wang Et Al: Contributions To Recent Ttl Variabilitymentioning

confidence: 99%

Quantifying contributions to the recent temperature variability in the tropical tropopause layer

2015

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Abstract. The recently observed variability in the tropical tropopause layer (TTL), which features a warming of 0.9 K over the past decade (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011), is investigated with a number of sensitivity experiments from simulations with NCAR's CESM-WACCM chemistry-climate model. The experiments have been designed to specifically quantify the contributions from natural as well as anthropogenic factors, such as solar variability (Solar), sea surface temperatures (SSTs), the quasi-biennial oscillation (QBO), stratospheric aerosols (Aerosol), greenhouse gases (GHGs) and the dependence on the vertical resolution in the model. The results show that, in the TTL from 2001 through 2011, a cooling in tropical SSTs leads to a weakening of tropical upwelling around the tropical tropopause and hence relative downwelling and adiabatic warming of 0.3 K decade −1 ; stronger QBO westerlies result in a 0.2 K decade −1 warming; increasing aerosols in the lower stratosphere lead to a 0.2 K decade −1 warming; a prolonged solar minimum contributes about 0.2 K decade −1 to a cooling; and increased GHGs have no significant influence. Considering all the factors mentioned above, we compute a net 0.5 K decade −1 warming, which is less than the observed 0.9 K decade −1 warming over the past decade in the TTL. Two simulations with different vertical resolution show that, with higher vertical resolution, an extra 0.8 K decade −1 warming can be simulated through the last decade compared with results from the "standard" low vertical resolution simulation. Model results indicate that the recent warming in the TTL is partly caused by stratospheric aerosols and mainly due to internal variability, i.e. the QBO and tropical SSTs. The vertical resolution can also strongly influence the TTL temperature response in addition to variability in the QBO and SSTs.

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The Brewer‐Dobson circulation

Cited by 586 publications

References 219 publications

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC

Quantifying contributions to the recent temperature variability in the tropical tropopause layer

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The Brewer‐Dobson circulation

Cited by 586 publications

References 219 publications

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

Relationship between solar activity and Δ14C peaks in AD 775, AD 994, and 660 BC

Quantifying contributions to the recent temperature variability in the tropical tropopause layer

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About

Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC