scholarly journals Large-scale heavy precipitation over central Europe and the role of atmospheric cyclone track types

2017 ◽  
Vol 38 ◽  
pp. e497-e517 ◽  
Author(s):  
Michael Hofstätter ◽  
Annemarie Lexer ◽  
Markus Homann ◽  
Günter Blöschl
Keyword(s):  
Central Europe ◽  
Large Scale ◽  
Heavy Precipitation ◽  
Cyclone Track

scholarly journals Climatology of Vb-cyclones, physical mechanisms and their impact on extreme precipitation over Central Europe

2015 ◽  
Vol 6 (1) ◽  
pp. 907-941
Author(s):  
M. Messmer ◽  
J. J. Gómez-Navarro ◽  
C. C. Raible
Keyword(s):  
Central Europe ◽  
Extreme Precipitation ◽  
Large Scale ◽  
Heavy Precipitation ◽  
Western Mediterranean ◽  
Physical Mechanisms ◽  
Detection And Tracking ◽  
The Alps ◽  
Precipitation Events ◽  
Thermodynamic Processes

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 Central Europe and the Alps. As the relevant processes triggering these so-called Vb-events and their impact on extreme precipitation are not yet fully understood, this study focusses 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 datasets is used to evaluate case-to-case precipitation amounts and to assess consistency between the two datasets. Both datasets 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 Alpine region 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 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.

scholarly journals Atmospheric processes triggering the Central European floods in June 2013

2014 ◽  
Vol 2 (1) ◽  
pp. 427-458 ◽  
Author(s):  
C. M. Grams ◽  
H. Binder ◽  
S. Pfahl ◽  
N. Piaget ◽  
H. Wernli
Keyword(s):  
Central Europe ◽  
Large Scale ◽  
Heavy Precipitation ◽  
Economic Loss ◽  
Precipitation Event ◽  
Rossby Wave Breaking ◽  
Atmospheric Processes ◽  
The North ◽  
Upper Level ◽  
Warm Conveyor Belts

Abstract. In June 2013 Central Europe was hit by a century flood affecting the Danube and Elbe catchments after a 4 day period of heavy precipitation and causing severe human and economic loss. In this study model analysis and observational data are investigated to reveal the key atmospheric processes that caused the heavy precipitation event. The period preceeding the flood was characterised by a weather regime associated with cool and unusual wet conditions resulting from repeated Rossby wave breaking (RWB). During the event a single RWB established a reversed baroclinicity in the low to mid troposphere in Central Europe with cool air trapped over the Alps and warmer air to the North. The upper-level cut-off resulting from the RWB instigated three consecutive cyclones in eastern Europe that unusually tracked westward during the days of heavy precipitation. Continuous large-scale slantwise ascent in so-called "upside down" warm conveyor belts (WCBs) associated with these cyclones is found as the key process that caused the 4 day heavy precipitation period. Fed by moisture sources from continental evapotranspiration, these WCBs unusually ascended equatorward along the southward sloping moist isentropes. Although "upside down" WCBs are climatologically rare events, they have great potential for causing high impact weather.

scholarly journals Climatology of Vb cyclones, physical mechanisms and their impact on extreme precipitation over Central Europe

2015 ◽  
Vol 6 (2) ◽  
pp. 541-553 ◽  
Author(s):  
M. Messmer ◽  
J. J. Gómez-Navarro ◽  
C. C. Raible
Keyword(s):  
Central Europe ◽  
Extreme Precipitation ◽  
Large Scale ◽  
Heavy Precipitation ◽  
Western Mediterranean ◽  
Data Sets ◽  
Detection And Tracking ◽  
Northern Side ◽  
The Alps ◽  
Obs Data

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.

scholarly journals Transient aggregation of convection: Observed behavior and underlying processes

2020 ◽  
pp. 1-46
Author(s):  
Hirohiko Masunaga ◽  
Christopher E. Holloway ◽  
Hironari Kanamori ◽  
Sandrine Bony ◽  
Thorwald H. M. Stein
Keyword(s):  
Large Scale ◽  
Heavy Precipitation ◽  
Aggregation Index ◽  
Budget Analysis ◽  
Cloud Clusters ◽  
Precipitation Regimes ◽  
Real Atmosphere ◽  
Static Energy ◽  
Underlying Processes

AbstractConvective self-aggregation is among the most striking features emerging from radiative-convective equilibrium simulations, but its relevance to convective disturbances observed in the real atmosphere remains under debate. This work seeks the observational signals of convective aggregation intrinsic to the life cycle of cloud clusters. To this end, composite time series of the Simple Convective Aggregation Index (SCAI), a metric of aggregation, and other variables from satellite measurements are constructed around the temporal maxima of precipitation. All the parameters analyzed are large-scale means over 10°×10° domains. The composite evolution for heavy precipitation regimes shows that cloud clusters are gathered into fewer members during a period of ±12 h as precipitation picks up. The high-cloud cover per cluster expands as the number of clusters drops, suggesting a transient occurrence of convective aggregation. The sign of the transient aggregation is less evident or entirely absent in light precipitation regimes. An energy budget analysis is performed in search of the physical processes underlying the transient aggregation. The column moist static energy (MSE) accumulates before the precipitation peak and dissipates after, accounted for primarily by the horizontal MSE advection. The domain-averaged column radiative cooling is greater in a more aggregated composite than in a less aggregated one, although the role of radiative-convective feedback behind this remains unclear.

scholarly journals Atmospheric processes triggering the central European floods in June 2013

2014 ◽  
Vol 14 (7) ◽  
pp. 1691-1702 ◽  
Author(s):  
C. M. Grams ◽  
H. Binder ◽  
S. Pfahl ◽  
N. Piaget ◽  
H. Wernli
Keyword(s):  
Central Europe ◽  
Large Scale ◽  
Heavy Precipitation ◽  
Economic Loss ◽  
Precipitation Event ◽  
Rossby Wave Breaking ◽  
Atmospheric Processes ◽  
The North ◽  
Upper Level ◽  
Warm Conveyor Belts

Abstract. In June 2013, central Europe was hit by a century flood affecting the Danube and Elbe catchments after a 4 day period of heavy precipitation and causing severe human and economic loss. In this study model analysis and observational data are investigated to reveal the key atmospheric processes that caused the heavy precipitation event. The period preceding the flood was characterised by a weather regime associated with cool and unusual wet conditions resulting from repeated Rossby wave breaking (RWB). During the event a single RWB established a reversed baroclinicity in the low to mid-troposphere in central Europe with cool air trapped over the Alps and warmer air to the north. The upper-level cut-off resulting from the RWB instigated three consecutive cyclones in eastern Europe that unusually tracked westward during the days of heavy precipitation. Continuous large-scale slantwise ascent in so-called "equatorward ascending" warm conveyor belts (WCBs) associated with these cyclones is found as the key process that caused the 4 day heavy precipitation period. Fed by moisture sources from continental evapotranspiration, these WCBs unusually ascended equatorward along the southward sloping moist isentropes. Although "equatorward ascending" WCBs are climatologically rare events, they have great potential for causing high impact weather.

scholarly journals Large-scale heavy precipitation and its link to atmospheric circulation in climate model outputs over central Europe 

2021 ◽  
Author(s):  
Romana Beranova ◽  
Jan Kysely
Keyword(s):  
Atmospheric Circulation ◽  
Central Europe ◽  
Large Scale ◽  
Climate Models ◽  
Climate Model ◽  
Heavy Precipitation ◽  
Human Society ◽  
Circulation Types ◽  
Recent Climate ◽  
Precipitation Events

<p>Heavy large-scale precipitation events are associated with large negative impacts on human society, mainly as they may trigger floods and landslides. Therefore, it is important to better understand underlying physical mechanisms leading to extremes and how they are reproduced in climate models.</p><p>The present study evaluates ability of current climate models to reproduce relationships between large-scale heavy precipitation and atmospheric circulation over central Europe. We use an ensemble of 32 regional climate model (RCM) simulations with the 0.11° resolution, taken from the Euro-CORDEX project. The statistics are compared for the recent climate simulations (1951-2005) against observations from the E-OBS gridded data set to identify main drawbacks of the RCMs. The large-scale heavy precipitation events are defined as days with at least 50% of all grid points over the examined area with heavy precipitation (exceeding the 75th or 90th percentile of the distribution of seasonal rainy days). The association with atmospheric circulation types is investigated through circulation types derived from sea level pressure using airflow indices (direction, strength and vorticity). The analysis is carried out separately for summer (JJA) and winter (DJF) season.</p><p>The number of days with large-scale heavy precipitation per season in observations reflects the seasonal precipitation sums (the larger precipitation sum the more days). In winter, the large-scale heavy precipitation is mainly associated with the west, northwest, southwest and cyclonic circulation types while in summer with the cyclonic, north, southwest and undefined types (in the observed data). Some RCM simulations are not able to reproduce the number of days with the large-scale heavy precipitation events and their relationships with circulation, especially in summer.</p>

Moisture sources of extreme Vb-floods in Central Europe

2020 ◽  
Author(s):  
Amelie Krug ◽  
Franziska Aemisegger ◽  
Michael Sprenger ◽  
Cristina Primo ◽  
Bodo Ahrens
Keyword(s):  
Mediterranean Sea ◽  
Central Europe ◽  
Heavy Precipitation ◽  
Western Mediterranean ◽  
Ocean Model ◽  
Moisture Uptake ◽  
European Continent ◽  
Moisture Sources ◽  
The North

<p>River floods are the most common and devastating natural hazard in Europe. In this study, we focus on a specific flood type which is associated with so-called Vb-cyclones. These extratropical cyclones are defined by their pathway from the western Mediterranean Sea north-eastward over northern Italy along the eastern fringe of the Alps towards Central Europe. Prominent examples of Vb-floods are the July 1954 and the August 2002 floods in the Elbe and Danube catchments as well as the Odra flooding during May/June 2010.</p><p>Only a few Vb-cyclones cause extreme flooding in Central Europe, even though about 2-5 follow the Vb pathway on average per year. The processes which intensify these flood triggering Vb-cyclones are only partly understood. One potential mechanism could be the soil-precipitation feedback over the continent. Moreover, the resulting latent heat release could re-enforce the atmospheric blocking conditions, e.g., over eastern Europe, that foster cyclones to follow the Vb-like pathway.</p><p>Our study aims to increase knowledge about potential feedback mechanisms by quantifying the role of specific moisture sources. We analysed the moisture uptake for selected extreme events in the 20<sup>th</sup> century based on backward trajectories in dynamically downscaled ERA-20C reanalysis. The downscaling was performed over Europe with a high-resolution and interactively coupled atmosphere-ocean model setup (COSMO-CLM+NEMO). The Mediterranean Sea contributed to rainfall in the affected river catchments often at the event start. Throughout the events, other main moisture uptake regions were the European continent pointing towards an important role of the soil-moisture precipitation feedback, but also other oceanic sources such as the North Atlantic, the North Sea, and the Baltic Sea were identified. The large variety of the identified sources highlights the complex dynamical interplay of different airmasses leading to convergence of moisture during particularly severe flood producing heavy precipitation events.</p>

The Role of Sense of Direction and Other Factors During Navigation in a Large-Scale, Unconstrained Environment

2013 ◽  
Author(s):  
Elisabeth J. Ploran ◽  
Ericka Rovira ◽  
James C. Thompson ◽  
Raja Parasuraman
Keyword(s):  
Large Scale ◽  
Sense Of Direction

Magnetic Properties of xCeO2•(50 − x) PbO•50B2O3 Glasses and Glass Ceramics

2017 ◽  
Vol 13 (1) ◽  
pp. 4486-4494 ◽  
Author(s):  
G.El Damrawi ◽  
F. Gharghar
Keyword(s):  
Magnetic Properties ◽  
Large Scale ◽  
Glass Ceramics ◽  
Magnetic Behavior ◽  
Crystal Formation ◽  
Dual Roles ◽  
Effective Agent ◽  
Ordered Structures ◽  
Essential Change

Cerium oxide in borate glasses of composition xCeO2·(50 − x)PbO·50B2O3 plays an important role in changing both microstructure and magnetic behaviors of the system. The structural role of CeO2 as an effective agent for cluster and crystal formation in borate network is clearly evidenced by XRD technique. Both structure and size of well-formed cerium separated clusters have an effective influence on the structural properties. The cluster aggregations are documented to be found in different range ordered structures, intermediate and long range orders are the most structures in which cerium phases are involved. The nano-sized crystallized cerium species in lead borate phase are evidenced to have magnetic behavior.  The criteria of building new specific borate phase enriched with cerium as ferrimagnetism has been found to keep the magnetization in large scale even at extremely high temperature. Treating the glass thermally or exposing it to an effective dose of ionized radiation is evidenced to have an essential change in magnetic properties. Thermal heat treatment for some of investigated materials is observed to play dual roles in the glass matrix. It can not only enhance alignment processes of the magnetic moment but also increases the capacity of the crystallite species in the magnetic phases. On the other hand, reverse processes are remarked under the effect of irradiation. The magnetization was found to be lowered, since several types of the trap centers which are regarded as defective states can be produced by effect of ionized radiation. 

The Impact of Quantitative Easing on Emerging Markets – Literature Review

e-Finanse ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 67-76
Author(s):  
Piotr Bartkiewicz
Keyword(s):  
Emerging Markets ◽  
Large Scale ◽  
Empirical Literature ◽  
Quantitative Easing ◽  
Methodological Choices ◽  
The Subject ◽  
Methodological Approaches ◽  
The Impact ◽  
Sufficient Precision

AbstractThe article presents the results of the review of the empirical literature regarding the impact of quantitative easing (QE) on emerging markets (EMs). The subject is of interest to policymakers and researchers due to the increasingly larger role of EMs in the world economy and the large-scale capital flows occurring after 2009. The review is conducted in a systematic manner and takes into consideration different methodological choices, samples and measurement issues. The paper puts the summarized results in the context of transmission channels identified in the literature. There are few distinct methodological approaches present in the literature. While there is a consensus regarding the direction of the impact of QE on EMs, its size and durability have not yet been assessed with sufficient precision. In addition, there are clear gaps in the empirical findings, not least related to relative underrepresentation of the CEE region (in particular, Poland).

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