On the dynamical coupling between atmospheric blocks and heavy precipitation events: A discussion of the southern Alpine flood in October 2000 ...
In October 2000, a high‐impact lake flood event occurred in southern Switzerland. During the month prior to the flood event three heavy precipitation events (HPEs) occurred. The first two events preconditioned the catchment and brought the lake close to its flood level. During the third event the la...
| Main Authors: | , , , |
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| Format: | Text |
| Language: | English |
| Published: |
Royal Meteorological Society
2019
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.7892/boris.123106 https://boris.unibe.ch/123106/ |
| Summary: | In October 2000, a high‐impact lake flood event occurred in southern Switzerland. During the month prior to the flood event three heavy precipitation events (HPEs) occurred. The first two events preconditioned the catchment and brought the lake close to its flood level. During the third event the lake level rose above the flood threshold. At the same time, anomalously high blocking activity was observed in the northern North‐Atlantic/European region. This study describes the synoptic development during the month prior to the flood and investigate the role of atmospheric blocking for the formation of the HPEs using ERA‐Interim data. Atmospheric blocks are identified as persistent negative potential vorticity (PV) anomalies in the upper troposphere. All three heavy precipitation events were forced by upper‐level equatorward elongated streams of stratospheric high‐PV air (PV streamers). These PV streamers formed in the strong deformation field upstream and downstream of single blocks or in between two blocks. ... |
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