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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ftunivbern:oai:boris.unibe.ch:71841 2023-08-20T04:08:13+02:00 Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation Piaget, Nicolas Froidevaux, Paul Arnaud Giannakaki, Paraskevi Gierth, Franziska Martius, Olivia Riemer, Michael Wolf, Gabriel Grams, Christian M. 2015 application/pdf https://boris.unibe.ch/71841/1/qj2496.pdf https://boris.unibe.ch/71841/ eng eng Royal Meteorological Society https://boris.unibe.ch/71841/ info:eu-repo/semantics/restrictedAccess Piaget, Nicolas; Froidevaux, Paul Arnaud; Giannakaki, Paraskevi; Gierth, Franziska; Martius, Olivia; Riemer, Michael; Wolf, Gabriel; Grams, Christian M. (2015). Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation. Quarterly Journal of the Royal Meteorological Society, 141(690), pp. 1922-1937. Royal Meteorological Society 10.1002/qj.2496 <http://dx.doi.org/10.1002/qj.2496> 550 Earth sciences & geology 910 Geography & travel info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed 2015 ftunivbern https://doi.org/10.1002/qj.2496 2023-07-31T21:19:53Z 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. Article in Journal/Newspaper North Atlantic BORIS (Bern Open Repository and Information System, University of Bern) Quarterly Journal of the Royal Meteorological Society 141 690 1922 1937 |
institution |
Open Polar |
collection |
BORIS (Bern Open Repository and Information System, University of Bern) |
op_collection_id |
ftunivbern |
language |
English |
topic |
550 Earth sciences & geology 910 Geography & travel |
spellingShingle |
550 Earth sciences & geology 910 Geography & travel Piaget, Nicolas Froidevaux, Paul Arnaud Giannakaki, Paraskevi Gierth, Franziska Martius, Olivia Riemer, Michael Wolf, Gabriel Grams, Christian M. Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation |
topic_facet |
550 Earth sciences & geology 910 Geography & travel |
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 |
Article in Journal/Newspaper |
author |
Piaget, Nicolas Froidevaux, Paul Arnaud Giannakaki, Paraskevi Gierth, Franziska Martius, Olivia Riemer, Michael Wolf, Gabriel Grams, Christian M. |
author_facet |
Piaget, Nicolas Froidevaux, Paul Arnaud Giannakaki, Paraskevi Gierth, Franziska Martius, Olivia Riemer, Michael Wolf, Gabriel Grams, Christian M. |
author_sort |
Piaget, Nicolas |
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://boris.unibe.ch/71841/1/qj2496.pdf https://boris.unibe.ch/71841/ |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Piaget, Nicolas; Froidevaux, Paul Arnaud; Giannakaki, Paraskevi; Gierth, Franziska; Martius, Olivia; Riemer, Michael; Wolf, Gabriel; Grams, Christian M. (2015). Dynamics of a local Alpine flooding event in October 2011: moisture source and large-scale circulation. Quarterly Journal of the Royal Meteorological Society, 141(690), pp. 1922-1937. Royal Meteorological Society 10.1002/qj.2496 <http://dx.doi.org/10.1002/qj.2496> |
op_relation |
https://boris.unibe.ch/71841/ |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1002/qj.2496 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
141 |
container_issue |
690 |
container_start_page |
1922 |
op_container_end_page |
1937 |
_version_ |
1774720379902754816 |