Reconciling the observed and modeled Southern Hemisphere circulation response to volcanic eruptions

McGraw, Marie C.; Barnes, Elizabeth A.; Deser, Clara

doi:10.1002/2016gl069835

Cited by 32 publications

(34 citation statements)

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“…The shutdown of the QBO-like oscillation in this configuration admittedly complicates the analysis (essentially, reducing our effective sample size), but the early evolution of the extratropical response appears to be insensitive to the initial phase of the QBO. annular modes of variability (e.g., Perlwitz and Graf 1995;Bittner et al 2016b;Barnes et al 2016;McGraw et al 2016). The annular modes dominate variability in the extratropical atmosphere in both hemispheres (Thompson and Wallace 2000) and have been linked to the response to external forcings, including greenhouse gases (e.g., Kushner et al 2001) and stratospheric ozone (e.g., Son et al 2010).…”

Section: Seasonality Of the Responsementioning

confidence: 99%

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The Circulation Response to Volcanic Eruptions: The Key Roles of Stratospheric Warming and Eddy Interactions

2019

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Proxy data and observations suggest that large tropical volcanic eruptions induce a poleward shift of the North Atlantic jet stream in boreal winter. However, there is far from universal agreement in models on this effect and its mechanism, and the possibilities of a corresponding jet shift in the Southern Hemisphere or the summer season have received little attention. Using a hierarchy of simplified atmospheric models, this study examines the impact of stratospheric aerosol on the extratropical circulation over the annual cycle. In particular, the models allow the separation of the dominant shortwave (surface cooling) and longwave (stratospheric warming) impacts of volcanic aerosol. It is found that stratospheric warming shifts the jet poleward in both the summer and winter hemispheres. The experiments cannot definitively rule out the role of surface cooling, but they provide no evidence that it shifts the jet poleward. Further study with simplified models demonstrates that the response to stratospheric warming is remarkably generic and does not depend critically on the boundary conditions (e.g., the planetary wave forcing) or the atmospheric physics (e.g., the treatment of radiative transfer and moist processes). It does, however, fundamentally involve both zonal-mean and eddy circulation feedbacks. The time scales, seasonality, and structure of the response provide further insight into the mechanism, as well as its connection to modes of intrinsic natural variability. These findings have implications for the interpretation of comprehensive model studies and for postvolcanic prediction.

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Section: Seasonality Of the Responsementioning

confidence: 99%

“…Furthermore, fewer studies have addressed the Southern Hemisphere (SH) response, where proxy data are scarce. Some studies have found a poleward shift of the SH winter jet (e.g., Karpechko et al 2010;McGraw et al 2016) while again others have found little or opposite response (e.g., Robock et al 2007;Roscoe and Haigh 2007).…”

Section: Introductionmentioning

confidence: 99%

The Circulation Response to Volcanic Eruptions: The Key Roles of Stratospheric Warming and Eddy Interactions

2019

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“…Some studies (Stenchikov et al, ; Ottera, ) have argued that models overestimate the stratospheric polar vortices, which could affect the tropospheric responses to volcanoes. Additionally, several simulation studies (Karpechko et al, ;Barnes et al, ; McGraw et al, ) have suggested that some large internal variabilities, such as the state of the ENSO, could play a role in the perceived discrepancies between the model results and observations. Both the fifth Coupled Model Intercomparison Project (CMIP5) simulations and Community Earth System Model (CESM) Large Ensemble simulations showed that, in the year following an eruption, a positive ENSO state (El Niño) was correlated with a weaker SAM anomaly whereas a negative ENSO states (La Niña) was correlated with a stronger SAM anomaly (Barnes et al, ; McGraw et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…ENSO remotely influences the SAM through a Rossby wave train and associated effects on storm tracks such that El Niño (La Niña) events generally result in negative (positive) SAM phase (Fogt and Bromwich, ; Fogt et al, ; Abram et al, ). In response to large volcanic eruptions, the stratospheric temperature gradient increases and strengthens the polar vortex, resulting in a significant positive SAM anomaly that propagates from the stratosphere into the troposphere in the 3 years following the eruption (Barnes et al, ; McGraw et al, ). However, internal climate variabilities such as strong El Niño events can weaken or even mask the positive responses in the eruption year.…”

Section: Discussionmentioning

confidence: 99%

“…Recent studies have attempted to study the potential impacts of volcanic events on SH atmospheric circulation but the models and the observations often show contradictory results (Roscoe and Haigh, 2007;Karpechko et al, 2010). Some researches ascribe the conflicting results to the uncertainty of the models and the internal variability like El Niño-Southern Oscillation (ENSO) of the climate system (Stenchikov et al, 2006;Ottera, 2008;Karpechko et al, 2010;Barnes et al, 2016;McGraw et al, 2016). However, observations of SH climate anomalies following volcanic eruptions are limited, as only El Chichón in 1982 and Pinatubo in 1991 have occurred since the beginning of the satellite era in 1979.…”

Section: Introductionmentioning

confidence: 99%

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The evolution and volcanic forcing of the southern annular mode during the past 300 years

Yang

Xiao

2017

Intl Journal of Climatology

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A positive change in the southern annular mode (SAM), which is the primary pattern of climate variability in the Southern Hemisphere, has been induced predominantly by polar stratospheric ozone depletion. However, the lack of long‐term observational records limits our understanding of the long‐term SAM behaviour. In this study, we found that the geochemical record of the LGB69 ice core from the eastern coast of Antarctica was significantly correlated with the winter SAM index (SAMI). In addition, we developed an annual mean SAMI beginning in 1701 based on 15 annually resolved ice cores and relevant proxy–climate relationships. Our reconstruction accounted for 54.8% of the total variance from 1957 to 2000 (the calibration period). We demonstrate that the recent positive phase shift in the annual mean SAMI since the 1970s is unprecedented, with the estimate for the latest regime in the 1990s reaching values 2.5 times the standard deviation above the baseline (1701–2000). This peak value also coincides with the largest 30‐ and 50‐year trends, which have occurred at the end of the 20th century. From the reconstructed SAMI, we also found that the response to large volcanic events was likely positive in the 3 years after the eruption, but this positive response can be masked by internal climate variability when a strong El Niño event occurs in the eruption year.

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Impact of volcanic aerosols on stratospheric ozone recovery

et al. 2017

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We use transient GFDL‐CM3 chemistry‐climate model simulations over the 2006–2100 period to show how the influence of volcanic aerosols on the extent and timing of ozone recovery varies with (a) future greenhouse gas scenarios (Representative Concentration Pathway (RCP)4.5 and RCP8.5) and (b) halogen loading. Current understanding is that elevated volcanic aerosols reduce ozone under high halogen loading but increase ozone under low halogen loading when the chemistry is more NOx dominated. With extremely low aerosol loadings (designated here as “background”), global stratospheric ozone burden is simulated to return to 1980 levels around 2050 in the RCP8.5 scenario but remains below 1980 levels throughout the 21st century in the RCP4.5 scenario. In contrast, with elevated volcanic aerosols, ozone column recovers more quickly to 1980 levels, with recovery dates ranging from the mid‐2040s in RCP8.5 to the mid‐2050s to early 2070s in RCP4.5. The ozone response in both future emission scenarios increases with enhanced volcanic aerosols. By 2100, the 1980 baseline‐adjusted global stratospheric ozone column is projected to be 20–40% greater in RCP8.5 and 110–200% greater in RCP4.5 with elevated volcanic aerosols compared to simulations with the extremely low background aerosols. The weaker ozone enhancement at 2100 in RCP8.5 than in RCP4.5 in response to elevated volcanic aerosols is due to a factor of 2.5 greater methane in RCP8.5 compared with RCP4.5. Our results demonstrate the substantial uncertainties in stratospheric ozone projections and expected recovery dates induced by volcanic aerosol perturbations that need to be considered in future model ozone projections.

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Reconciling the observed and modeled Southern Hemisphere circulation response to volcanic eruptions

Cited by 32 publications

References 34 publications

The Circulation Response to Volcanic Eruptions: The Key Roles of Stratospheric Warming and Eddy Interactions

The Circulation Response to Volcanic Eruptions: The Key Roles of Stratospheric Warming and Eddy Interactions

The evolution and volcanic forcing of the southern annular mode during the past 300 years

Impact of volcanic aerosols on stratospheric ozone recovery

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