Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation
Alpine heavy precipitation events often affect small catchments, although the circulation pattern leading to the event extends over the entire North Atlantic. The various scale interactions involved are particularly challenging for the numerical weather prediction of such events. Unlike previous stu...
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ftdatacite:10.7892/boris.71841 2023-05-15T17:28:53+02:00 Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation Giannakaki, Paraskevi Gierth, Franziska Riemer, Michael Piaget, Nicolas Grams, Christian M. Froidevaux, Paul Arnaud Wolf, Gabriel Martius, Olivia 2015 application/pdf https://dx.doi.org/10.7892/boris.71841 http://boris.unibe.ch/71841/ en eng Royal Meteorological Society info:eu-repo/semantics/restrictedAccess 910 Geography & travel 550 Earth sciences & geology Text article-journal ScholarlyArticle 2015 ftdatacite https://doi.org/10.7892/boris.71841 2021-11-05T12:55:41Z Alpine heavy precipitation events often affect small catchments, although the circulation pattern leading to the event extends over the entire North Atlantic. The various scale interactions involved are particularly challenging for the numerical weather prediction of such events. Unlike previous studies focusing on the southern Alps, here a comprehensive study of a heavy precipitation event in the northern Alps in October 2011 is presented with particular focus on the role of the large-scale circulation in the North Atlantic/European region. During the event exceptionally high amounts of total precipitable water occurred in and north of the Alps. This moisture was initially transported along the flanks of a blocking ridge over the North Atlantic. Subsequently, strong and persistent northerly flow established at the upstream flank of a trough over Europe and steered the moisture towards the northern Alps. Lagrangian diagnostics reveal that a large fraction of the moisture emerged from the West African coast where a subtropical upper-level cut-off low served as an important moisture collector. Wave activity flux diagnostics show that the ridge was initiated as part of a low-frequency, large-scale Rossby wave train while convergence of fast transients helped to amplify it locally in the North Atlantic. A novel diagnostic for advective potential vorticity tendencies sheds more light on this amplification and further emphasizes the role of the ridge in amplifying the trough over Europe. Operational forecasts misrepresented the amplitude and orientation of this trough. For the first time, this study documents an important pathway for northern Alpine flooding, in which the interaction of synoptic-scale to large-scale weather systems and of long-range moisture transport from the Tropics are dominant. Moreover, the trapping of moisture in a subtropical cut-off near the West African coast is found to be a crucial precursor to the observed European high-impact weather. Text North Atlantic DataCite Metadata Store (German National Library of Science and Technology) |
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DataCite Metadata Store (German National Library of Science and Technology) |
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language |
English |
topic |
910 Geography & travel 550 Earth sciences & geology |
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910 Geography & travel 550 Earth sciences & geology Giannakaki, Paraskevi Gierth, Franziska Riemer, Michael Piaget, Nicolas Grams, Christian M. Froidevaux, Paul Arnaud Wolf, Gabriel Martius, Olivia Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation |
topic_facet |
910 Geography & travel 550 Earth sciences & geology |
description |
Alpine heavy precipitation events often affect small catchments, although the circulation pattern leading to the event extends over the entire North Atlantic. The various scale interactions involved are particularly challenging for the numerical weather prediction of such events. Unlike previous studies focusing on the southern Alps, here a comprehensive study of a heavy precipitation event in the northern Alps in October 2011 is presented with particular focus on the role of the large-scale circulation in the North Atlantic/European region. During the event exceptionally high amounts of total precipitable water occurred in and north of the Alps. This moisture was initially transported along the flanks of a blocking ridge over the North Atlantic. Subsequently, strong and persistent northerly flow established at the upstream flank of a trough over Europe and steered the moisture towards the northern Alps. Lagrangian diagnostics reveal that a large fraction of the moisture emerged from the West African coast where a subtropical upper-level cut-off low served as an important moisture collector. Wave activity flux diagnostics show that the ridge was initiated as part of a low-frequency, large-scale Rossby wave train while convergence of fast transients helped to amplify it locally in the North Atlantic. A novel diagnostic for advective potential vorticity tendencies sheds more light on this amplification and further emphasizes the role of the ridge in amplifying the trough over Europe. Operational forecasts misrepresented the amplitude and orientation of this trough. For the first time, this study documents an important pathway for northern Alpine flooding, in which the interaction of synoptic-scale to large-scale weather systems and of long-range moisture transport from the Tropics are dominant. Moreover, the trapping of moisture in a subtropical cut-off near the West African coast is found to be a crucial precursor to the observed European high-impact weather. |
format |
Text |
author |
Giannakaki, Paraskevi Gierth, Franziska Riemer, Michael Piaget, Nicolas Grams, Christian M. Froidevaux, Paul Arnaud Wolf, Gabriel Martius, Olivia |
author_facet |
Giannakaki, Paraskevi Gierth, Franziska Riemer, Michael Piaget, Nicolas Grams, Christian M. Froidevaux, Paul Arnaud Wolf, Gabriel Martius, Olivia |
author_sort |
Giannakaki, Paraskevi |
title |
Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation |
title_short |
Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation |
title_full |
Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation |
title_fullStr |
Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation |
title_full_unstemmed |
Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation |
title_sort |
dynamics of a local alpine flooding event in october 2011: moisture source and large-scale circulation |
publisher |
Royal Meteorological Society |
publishDate |
2015 |
url |
https://dx.doi.org/10.7892/boris.71841 http://boris.unibe.ch/71841/ |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.7892/boris.71841 |
_version_ |
1766122011082358784 |