The role of circulation anomalies in the emergence of extreme precipitation events in Central Europe

0508817 - ÚFA 2020 DE eng A - Abstrakt
Gvoždíková, B. - Müller, Miloslav
The role of circulation anomalies in the emergence of extreme precipitation events in Central Europe.
EMS Annual Meeting Abstracts, Vol. 16. Berlin: European Meteorological Society, 2019.
[EMS Annual Meeting 2019. 09.09.2019-13.09.2019, Copenhagen]
Institucionální podpora: RVO:68378289
Klíčová slova: extreme precipitation events * atmospheric circulation conditions * radar reanalysis data * Central Europe
Obor OECD: Meteorology and atmospheric sciences
https://meetingorganizer.copernicus.org/EMS2019/EMS2019-744.pdf

Largescale extreme precipitation events (EPEs) seem to repeat over time in accordance with recurring atmospheric
circulation conditions. This suggests the possibility of classification of EPEs into several groups with different
sets of circulation anomalies related to the occurrence of EPEs. In the presented study, we aim to define groups
of EPEs with characteristic circulation anomalies, as well as to find out whether a climatology of circulation
anomalies relates to EPEs climatology. We use the ERA5 reanalysis data to divide a set of 43 Central European
events since 1979 into three groups representing (i) events with dominating moisture flux from the north, (ii) events
with dominating moisture flux from the west, (iii) and low flux events. Within these groups, various averaged
meteorological variables are displayed in relative numbers (in terms of not exceeding a given value), which makes
it possible to assess the significance of an anomaly for a group of events. A strong anomaly of moisture flux from
the north is evident within the first group, as high values of moisture flux coincide with the occurrence of EPEs.
The presence of such a strong anomaly is not so obvious in other groups, although there exist smaller anomalies
associated with the presence of a cyclone over Central Europe, such as anomalies of vertical motion, cyclonic
vorticity, low-level convergence or divergence aloft. Because some of the circulation extremes seem to be directly
connected to extremes in precipitation, there is a potential to use circulation anomalies as predictors of EPEs. Using
ERA-Interim re-forecasts, it turns out that the medium range forecast skill of some circulation anomalies is better
than the skill of quantitative precipitation forecast, which would be beneficial for EPEs early warnings.
Trvalý link: http://hdl.handle.net/11104/0299623