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...
Published in: | Quarterly Journal of the Royal Meteorological Society |
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ftunivreading:oai:centaur.reading.ac.uk:76983 2024-06-23T07:54:57+00:00 Dynamics of a local Alpine flooding event in October 2011: moisture source and large‐scale circulation Piaget, Nicolas Froidevaux, Paul Giannakaki, Paraskevi Gierth, Franziska Martius, Olivia Riemer, Michael Wolf, Gabriel Grams, Christian M. 2014 https://centaur.reading.ac.uk/76983/ https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.2496 unknown Royal Meteorological Society Piaget, N., Froidevaux, P., Giannakaki, P., Gierth, F., Martius, O., Riemer, M., Wolf, G. <https://centaur.reading.ac.uk/view/creators/90006911.html> and Grams, C. M. (2014) 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. ISSN 1477-870X doi: https://doi.org/10.1002/qj.2496 <https://doi.org/10.1002/qj.2496> Article PeerReviewed 2014 ftunivreading https://doi.org/10.1002/qj.2496 2024-06-11T15:07:33Z 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 CentAUR: Central Archive at the University of Reading Quarterly Journal of the Royal Meteorological Society 141 690 1922 1937 |
institution |
Open Polar |
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CentAUR: Central Archive at the University of Reading |
op_collection_id |
ftunivreading |
language |
unknown |
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 Giannakaki, Paraskevi Gierth, Franziska Martius, Olivia Riemer, Michael Wolf, Gabriel Grams, Christian M. |
spellingShingle |
Piaget, Nicolas Froidevaux, Paul 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 |
author_facet |
Piaget, Nicolas Froidevaux, Paul 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 |
2014 |
url |
https://centaur.reading.ac.uk/76983/ https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.2496 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
Piaget, N., Froidevaux, P., Giannakaki, P., Gierth, F., Martius, O., Riemer, M., Wolf, G. <https://centaur.reading.ac.uk/view/creators/90006911.html> and Grams, C. M. (2014) 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. ISSN 1477-870X doi: https://doi.org/10.1002/qj.2496 <https://doi.org/10.1002/qj.2496> |
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_ |
1802647309881704448 |