Abstract
Abstract. Cyclones, which develop over the western Mediterranean and move northeastward are a major source of extreme weather and known to be responsible for heavy precipitation over the northern side of the Alpine range and Central Europe. As the relevant processes triggering these so-called Vb events and their impact on extreme precipitation are not yet fully understood, this study focuses on gaining insight into the dynamics of past events. For this, a cyclone detection and tracking tool is applied to the ERA-Interim reanalysis (1979–2013) to identify prominent Vb situations. Precipitation in the ERA-Interim and the E-OBS data sets is used to evaluate case-to-case precipitation amounts and to assess consistency between the two data sets. Both data sets exhibit high variability in precipitation amounts among different Vb events. While only 23 % of all Vb events are associated with extreme precipitation, around 15 % of all extreme precipitation days (99 percentile) over the northern Alpine region and Central Europe are induced by Vb events, although Vb cyclones are rare events (2.3 per year). To obtain a better understanding of the variability within Vb events, the analysis of the 10 heaviest and lowest precipitation Vb events reveals noticeable differences in the state of the atmosphere. These differences are most pronounced in the geopotential height and potential vorticity field, indicating a much stronger cyclone for heavy precipitation events. The related differences in wind direction are responsible for the moisture transport around the Alps and the orographical lifting along the northern slopes of the Alps. These effects are the main reasons for a disastrous outcome of Vb events, and consequently are absent in the Vb events associated with low precipitation. Hence, our results point out that heavy precipitation related to Vb events is mainly related to large-scale dynamics rather than to thermodynamic processes.
Highlights
High-impact weather events may have dramatic impacts on society, being a problem that could be potentially enhanced under a changing climate (IPCC-SREX, 2012)
Considering ERA-Interim (E-OBS) data set in this period of time the rare Vb events are responsible for almost 15 % (14 %) of extreme precipitation days in the northern Alpine region and Central Europe
The results concerning the basic climatology of Vb cyclones show a good agreement with the findings previously reported by Hofstätter and Chimani (2012), i.e. the rareness of Vb cyclones (2.3 Vb cyclone appearances per year), the peak of Vb cyclones in spring and a general agreement of the exact appearance of 65 % of all Vb cyclones compared to Hofstätter and Chimani (2012)
Summary
High-impact weather events may have dramatic impacts on society, being a problem that could be potentially enhanced under a changing climate (IPCC-SREX, 2012). Such events lead to great economical damage, and to personal damage (Kron et al, 2012; Held et al, 2013; Donat et al, 2011). The cyclone moves eastward via Italy and the Adriatic Sea, before it turns northward to the Black Sea or Saint Petersburg.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
