Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty

Abstract The observed strengthening of the Northern Hemisphere (NH) polar vortex after tropical volcanic eruptions appears to be underestimated by coupled climate models. However, there are only a limited number of observed eruptions, which makes the attribution of volcanic signals difficult, becaus...

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Main Authors: Matthias Bittner, Hauke Schmidt, Claudia Timmreck, Frank Sienz
Format: Article
Language:English
Published: Wiley 2016-09-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1002/2016GL070587
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author Matthias Bittner
Hauke Schmidt
Claudia Timmreck
Frank Sienz
author_facet Matthias Bittner
Hauke Schmidt
Claudia Timmreck
Frank Sienz
author_sort Matthias Bittner
collection DOAJ
description Abstract The observed strengthening of the Northern Hemisphere (NH) polar vortex after tropical volcanic eruptions appears to be underestimated by coupled climate models. However, there are only a limited number of observed eruptions, which makes the attribution of volcanic signals difficult, because the polar vortex is also influenced by other external forcing factors as well as internal variability. We show with a 100‐member ensemble of historical (1850–2005) simulations with the Max Planck Institute Earth System Model that an ensemble larger than what is provided by the Coupled Model Intercomparison Project Phase 5 (CMIP5) models is needed to detect a statistically significant NH polar vortex strengthening. The most robust signal can be found when only the two strongest eruptions (Krakatau and Pinatubo) are considered in contrast to including smaller eruptions to increase the sample size. For these two strongest eruptions, the mean of 15 CMIP5 models shows a statistically significant strengthening of the NH polar vortex as well.
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spelling doaj-art-fb4e933a01d543dd9f4f02e015ebf8812025-08-20T01:52:06ZengWileyGeophysical Research Letters0094-82761944-80072016-09-0143179324933210.1002/2016GL070587Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertaintyMatthias Bittner0Hauke Schmidt1Claudia Timmreck2Frank Sienz3Max Planck Institute for Meteorology Hamburg GermanyMax Planck Institute for Meteorology Hamburg GermanyMax Planck Institute for Meteorology Hamburg GermanyMax Planck Institute for Meteorology Hamburg GermanyAbstract The observed strengthening of the Northern Hemisphere (NH) polar vortex after tropical volcanic eruptions appears to be underestimated by coupled climate models. However, there are only a limited number of observed eruptions, which makes the attribution of volcanic signals difficult, because the polar vortex is also influenced by other external forcing factors as well as internal variability. We show with a 100‐member ensemble of historical (1850–2005) simulations with the Max Planck Institute Earth System Model that an ensemble larger than what is provided by the Coupled Model Intercomparison Project Phase 5 (CMIP5) models is needed to detect a statistically significant NH polar vortex strengthening. The most robust signal can be found when only the two strongest eruptions (Krakatau and Pinatubo) are considered in contrast to including smaller eruptions to increase the sample size. For these two strongest eruptions, the mean of 15 CMIP5 models shows a statistically significant strengthening of the NH polar vortex as well.https://doi.org/10.1002/2016GL070587volcanic eruptionspolar vortexinternal variabilitylarge ensemble
spellingShingle Matthias Bittner
Hauke Schmidt
Claudia Timmreck
Frank Sienz
Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty
Geophysical Research Letters
volcanic eruptions
polar vortex
internal variability
large ensemble
title Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty
title_full Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty
title_fullStr Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty
title_full_unstemmed Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty
title_short Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty
title_sort using a large ensemble of simulations to assess the northern hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty
topic volcanic eruptions
polar vortex
internal variability
large ensemble
url https://doi.org/10.1002/2016GL070587
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