scholarly journals Patterns of extreme weather associated with observed and proxy River Ammer flood records

2017 ◽  
Author(s):  
Norel Rimbu ◽  
Monica Ionita ◽  
Markus Czymzik ◽  
Achim Brauer ◽  
Gerrit Lohmann
Keyword(s):  
Solar Activity ◽  
Radiative Forcing ◽  
Large Scale ◽  
Western Europe ◽  
Extreme Temperature ◽  
Heavy Precipitation ◽  
Flood Frequency ◽  
Discharge Data ◽  
Blocking High ◽  
Northeastern Europe

Abstract. We investigate the relationship between the variability in the frequency of River Ammer floods (southern Germany) and temperature/precipitation extremes over Europe using observational River Ammer discharge data back to 1926 and the 5500-year-long flood layer record from varved Lake Ammersee sediments. We show that observed River Ammer flood frequency variability is not only related with local extreme precipitation, but also with large-scale temperature extreme anomalies. Less (more) extreme high temperatures over central and western (northeastern) Europe are recorded during periods of increased River Ammer flood frequency. We argue that changing radiative forcing due to cloudiness anomaly patterns associated with River Ammer floods induce these extreme temperature anomalies. Consistent patterns are obtained using observed discharge and proxy flood layer frequency data. Furthermore, a higher frequency of observed River Ammer floods and flood layers is associated with enhanced blocking activity over northeastern Europe. A blocking high over this region increases the probability of wave breaking and associated heavy precipitation over western Europe. A similar blocking pattern is associated with periods of reduced solar activity. Consequently, solar modulated changes in blocking frequency over northeastern Europe could explain the connection between River Ammer floods and solar activity, as also identified in previous studies. We argue that multi-decadal to millennial flood frequency variations in the Mid- to Late Holocene flood layer record from Lake Ammersee characterizes also the extreme temperatures in northeastern Europe.

scholarly journals Atmospheric circulation patterns associated with the variability of River Ammer floods: evidence from observed and proxy data

2016 ◽  
Vol 12 (2) ◽  
pp. 377-385 ◽  
Author(s):  
Norel Rimbu ◽  
Markus Czymzik ◽  
Monica Ionita ◽  
Gerrit Lohmann ◽  
Achim Brauer
Keyword(s):  
Time Series ◽  
Atmospheric Circulation ◽  
Western Europe ◽  
Wave Train ◽  
Heavy Precipitation ◽  
Circulation Pattern ◽  
Flood Frequency ◽  
Discharge Data ◽  
Western Asia ◽  
Instrumental Period

Abstract. The relationship between the frequency of River Ammer floods (southern Germany) and atmospheric circulation variability is investigated based on observational Ammer River discharge data back to 1926 and a flood layer time series from varved sediments of the downstream Lake Ammer for the pre-instrumental period back to 1766. A composite analysis reveals that, at synoptic timescales, observed River Ammer floods are associated with enhanced moisture transport from the Atlantic Ocean and the Mediterranean towards the Ammer region, a pronounced trough over western Europe as well as enhanced potential vorticity at upper levels. We argue that this synoptic-scale configuration can trigger heavy precipitation and floods in the Ammer region. Interannual to multidecadal increases in flood frequency, as detected in the instrumental discharge record, are associated with a wave train pattern extending from the North Atlantic to western Asia, with a prominent negative center over western Europe. A similar atmospheric circulation pattern is associated with increases in flood layer frequency in the Lake Ammer sediment record during the pre-instrumental period. We argue that the complete flood layer time series from Lake Ammer sediments covering the last 5500 years contains information about atmospheric circulation variability on interannual to millennial timescales.

scholarly journals The role of climatic factors in evolving flood patterns in a Mediterranean Region (1301–2012)

2014 ◽  
Vol 11 (8) ◽  
pp. 9145-9182 ◽  
Author(s):  
A. Barrera-Escoda ◽  
M. C. Llasat
Keyword(s):  
Solar Activity ◽  
Mediterranean Region ◽  
General Circulation ◽  
Climatic Factors ◽  
Late Summer ◽  
Heavy Precipitation ◽  
Significant Rise ◽  
Flood Frequency ◽  
Quasi Biennial Oscillation

Abstract. Data on flood occurrence and flood impacts for the last seven centuries in the northeast Iberian Peninsula have been analysed in order to characterise long-term trends, anomalous periods and their relationship with different climatic factors such as precipitation, general circulation and solar activity. Catastrophic floods do not present a statistically significant trend, whereas extraordinary floods have seen a significant rise, especially from 1850 on, and were responsible for the total increase in flooding in the region. This rise can be mainly attributed to small coastal catchments, which have experienced a marked increase in developed land and population, resulting in changes in land use and greater vulnerability. Changes in precipitation alone cannot explain the variation in flood patterns, although a certain increase was shown in late summer–early autumn, when extraordinary floods are most frequently recorded. The relationship between North Atlantic circulation and floods is not as strong, due to the important role of mesoscale factors in heavy precipitation in the northwest of the Mediterranean region. However it can explain the variance to some extent, mainly in relation to the catastrophic floods experienced during the autumn. Solar activity has some impact on changes in catastrophic floods with cycles related to the Quasi-Biennial Oscillation and the Gleissberg solar cycle. In addition, anomalous periods of high flood frequency in autumn generally occurred during periods of increased solar activity. The physical influence of the latter in general circulation patterns, the high troposphere and the stratosphere, has been analysed in order to ascertain its role in causing floods.

Measuring Flood Discharge

2017 ◽  
Author(s):  
Marian Muste ◽  
Ton Hoitink
Keyword(s):  
Real Time ◽  
Water Resource Management ◽  
Large Scale ◽  
Water Cycle ◽  
Ground Truth ◽  
Flood Frequency ◽  
Main Concern ◽  
Essential Difference ◽  
Discharge Data ◽  
Ground Truth Data

With a continuous global increase in flood frequency and intensity, there is an immediate need for new science-based solutions for flood mitigation, resilience, and adaptation that can be quickly deployed in any flood-prone area. An integral part of these solutions is the availability of river discharge measurements delivered in real time with high spatiotemporal density and over large-scale areas. Stream stages and the associated discharges are the most perceivable variables of the water cycle and the ones that eventually determine the levels of hazard during floods. Consequently, the availability of discharge records (a.k.a. streamflows) is paramount for flood-risk management because they provide actionable information for organizing the activities before, during, and after floods, and they supply the data for planning and designing floodplain infrastructure. Moreover, the discharge records represent the ground-truth data for developing and continuously improving the accuracy of the hydrologic models used for forecasting streamflows. Acquiring discharge data for streams is critically important not only for flood forecasting and monitoring but also for many other practical uses, such as monitoring water abstractions for supporting decisions in various socioeconomic activities (from agriculture to industry, transportation, and recreation) and for ensuring healthy ecological flows. All these activities require knowledge of past, current, and future flows in rivers and streams. Given its importance, an ability to measure the flow in channels has preoccupied water users for millennia. Starting with the simplest volumetric methods to estimate flows, the measurement of discharge has evolved through continued innovation to sophisticated methods so that today we can continuously acquire and communicate the data in real time. There is no essential difference between the instruments and methods used to acquire streamflow data during normal conditions versus during floods. The measurements during floods are, however, complex, hazardous, and of limited accuracy compared with those acquired during normal flows. The essential differences in the configuration and operation of the instruments and methods for discharge estimation stem from the type of measurements they acquire—that is, discrete and autonomous measurements (i.e., measurements that can be taken any time any place) and those acquired continuously (i.e., estimates based on indirect methods developed for fixed locations). Regardless of the measurement situation and approach, the main concern of the data providers for flooding (as well as for other areas of water resource management) is the timely delivery of accurate discharge data at flood-prone locations across river basins.

scholarly journals Solar modulation of flood frequency in central Europe during spring and summer on interannual to multi-centennial timescales

2016 ◽  
Vol 12 (3) ◽  
pp. 799-805 ◽  
Author(s):  
Markus Czymzik ◽  
Raimund Muscheler ◽  
Achim Brauer
Keyword(s):  
Solar Activity ◽  
Atmospheric Circulation ◽  
Central Europe ◽  
Empirical Support ◽  
Total Solar Irradiance ◽  
Flood Frequency ◽  
Solar Modulation ◽  
Top Down ◽  
Discharge Data ◽  
Atmospheric Circulation Patterns

Abstract. Solar influences on climate variability are one of the most controversially discussed topics in climate research. We analyze solar forcing of flood frequency in central Europe during spring and summer on interannual to multi-centennial timescales, integrating daily discharge data of the River Ammer (southern Germany) back to AD 1926 (∼  solar cycles 16–23) and the 5500-year flood layer record from varved sediments of the downstream Ammersee. Flood frequency in the River Ammer discharge record is significantly correlated to changes in solar activity when the flood record lags the solar signal by 2–3 years (2-year lag: r = −0.375, p = 0.01; 3-year lag: r = −0.371, p = 0.03). Flood layer frequency in the Ammersee sediment record depicts distinct multi-decadal variations and significant correlations to a total solar irradiance reconstruction (r = −0.4, p <  0.0001) and 14C production rates (r = 0.37, p <  0.0001), reflecting changes in solar activity. On all timescales, flood frequency is higher when solar activity is reduced. In addition, the configuration of atmospheric circulation associated with periods of increased River Ammer flood frequency broadly resembles that during intervals of reduced solar activity, as expected to be induced by the so-called solar top-down mechanism by model studies. Both atmospheric patterns are characterized by an increase in meridional airflow associated with enhanced atmospheric blocking over central Europe. Therefore, the significant correlations as well as similar atmospheric circulation patterns might provide empirical support for a solar influence on hydroclimate extremes in central Europe during spring and summer by the so-called solar top-down mechanism.

scholarly journals Atmospheric circulation patterns associated to the variability of River Ammer floods: evidence from observed and proxy data

2015 ◽  
Vol 11 (5) ◽  
pp. 4483-4504 ◽  
Author(s):  
N. Rimbu ◽  
M. Czymzik ◽  
M. Ionita ◽  
G. Lohmann ◽  
A. Brauer
Keyword(s):  
Time Series ◽  
Atmospheric Circulation ◽  
Time Scales ◽  
Western Europe ◽  
Wave Train ◽  
Circulation Pattern ◽  
Flood Frequency ◽  
Discharge Data ◽  
Western Asia ◽  
Instrumental Period

Abstract. The relationship between the frequency of River Ammer floods (southern Germany) and atmospheric circulation variability is investigated based on observational Ammer discharge data back to 1926 and a flood layer time series from varved sediments of the downstream Lake Ammersee for the pre-instrumental period back to 1766. A composite analysis reveals that, at synoptic time scales, observed River Ammer floods are associated with enhanced moisture transport from the Atlantic Ocean and the Mediterranean towards the Ammer region, a pronounced trough over Western Europe as well as enhanced potential vorticity at upper levels. We argue that this synoptic scale configuration can trigger heavy precipitation and floods in the Ammer region. Interannual to multidecadal increases in flood frequency as recorded in the instrumental discharge record are associated to a wave-train pattern extending from the North Atlantic to western Asia with a prominent negative center over western Europe. A similar atmospheric circulation pattern is associated to increases in flood layer frequency in the Lake Ammersee sediment record during the pre-instrumental period. We argue that the complete flood layer time-series from Lake Ammersee sediments covering the last 5500 years, contains information about atmospheric circulation variability on inter-annual to millennial time-scales.

scholarly journals Changes in flood frequencies in Switzerland since 1500

2010 ◽  
Vol 14 (8) ◽  
pp. 1581-1594 ◽  
Author(s):  
P. Schmocker-Fackel ◽  
F. Naef
Keyword(s):  
Czech Republic ◽  
Solar Activity ◽  
Large Scale ◽  
Flood Frequency ◽  
Flood Events ◽  
The Czech Republic ◽  
Northern Switzerland ◽  
The Past ◽  
Current Period ◽  
The Individual

Abstract. In northern Switzerland, an accumulation of large flood events has occurred since the 1970s, preceded by a prolonged period with few floods (Schmocker-Fackel and Naef, 2010). How have Swiss flood frequencies changed over the past 500 years? And how does the recent increase in flood frequencies compare with other periods in this half millennium? We collected historical flood data for 14 Swiss catchments dating back to 1500 AC. All catchments experienced marked fluctuations in flood frequencies, and we were able to identify four periods of frequent flooding in northern Switzerland, lasting between 30 and 100 years (1560–1590, 1740–1790, 1820–1940 and since 1970). The current period of increased flood frequencies has not yet exceeded those observed in the past. We tested whether the flood frequency fluctuation could be explained with generalised climatic indices like solar activity or the NAO. The first three periods of low flood frequency in Switzerland correspond to periods of low solar activity. However, after 1810 no relationship between solar activity and flood frequency was found, nor could a relationship be established between reconstructed NAO indices or reconstructed Swiss temperatures. We found re-occurring spatial patterns of flood frequencies on a European scale, with the Swiss periods of frequent flooding often in phase with those in the Czech Republic, Italy and Spain and less often with those in Germany. The pattern of flooding in northern Switzerland and the Czech Republic seem to be rather similar, although the individual flood events do not match. This comparison of flooding patterns in different European countries suggests that changes in large scale atmospheric circulation are responsible for the flood frequency fluctuations.

scholarly journals Changes in flood frequencies in Switzerland since 1500

2010 ◽  
Vol 7 (1) ◽  
pp. 529-560 ◽  
Author(s):  
P. Schmocker-Fackel ◽  
F. Naef
Keyword(s):  
Czech Republic ◽  
Solar Activity ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Flood Frequency ◽  
Flood Events ◽  
The Czech Republic ◽  
Northern Switzerland ◽  
Atmospheric Circulation Patterns ◽  
The Past

Abstract. In Northern Switzerland, an accumulation of large flood events has occurred since the 1970s, preceded by a prolonged period with few floods (Schmocker-Fackel and Naef, 2010). How have Swiss flood frequencies changed over the past 500 years? And how does the recent increase in flood frequencies compare with other periods in this half millennium? We collected historical flood data for 14 Swiss catchments dating back to 1500 AC. All catchments experienced marked fluctuations in flood frequencies, and we were able to identify four periods of frequent flooding in Northern Switzerland, lasting between 30 and 100 years. The current period of increased flood frequencies has not yet exceeded those observed in the past. We tested whether the flood frequency fluctuation could be explained with generalised climatic indices like solar activity or atmospheric circulation patterns. The first three periods of low flood frequency in Switzerland correspond to periods of low solar activity. However, after 1810 no relationship between solar activity and flood frequency were found. Nor could a relationship be established between reconstructed NAO indices or reconstructed Swiss summer temperatures. We found re-occurring spatial patterns of flood frequencies on a European scale, with the Swiss periods of frequent flooding often in phase with those in the Czech Republic, Italy and Spain and less often with those in Germany. The pattern of flooding in Northern Switzerland and the Czech Republic seem to be rather similar, although the individual flood events do not match. This comparison of flooding patterns in different European countries suggests that changes in large scale atmospheric circulation are responsible for the flood frequency fluctuations.

scholarly journals Solar modulation of flood frequency in Central Europe during spring and summer on inter-annual to millennial time-scales

2015 ◽  
Vol 11 (5) ◽  
pp. 4833-4850 ◽  
Author(s):  
M. Czymzik ◽  
R. Muscheler ◽  
A. Brauer
Keyword(s):  
Solar Activity ◽  
Central Europe ◽  
Time Scales ◽  
Decadal Variability ◽  
Empirical Support ◽  
Flood Frequency ◽  
Solar Modulation ◽  
Solar Cycles ◽  
Discharge Data ◽  
Discharge Record

Abstract. Solar influences on climate variability are one of the most controversially discussed topics in climate research. We analyze solar forcing of flood frequency in Central Europe on inter-annual to millennial time-scales using daily discharge data of River Ammer (southern Germany) back to AD 1926 and revisiting the 5500 year flood layer time-series from varved sediments of the downstream Lake Ammersee. Flood frequency in the discharge record is significantly correlated to changes in solar activity during solar cycles 16–23 (r = −0.47, p < 0.0001, n = 73). Flood layer frequency (n = 1501) in the sediment record depicts distinct multi-decadal variability and significant correlations to 10Be fluxes from a Greenland ice core (r = 0.45, p < 0.0001) and 14C production rates (r =0.36, p < 0.0001), proxy records of solar activity. Flood frequency is higher when solar activity is reduced. These correlations between flood frequency and solar activity might provide empirical support for the solar top-down mechanism expected to modify the mid-latitude storm tracks over Europe by model studies. A lag of flood frequency responses in the Ammer discharge record to changes in solar activity of about one to three years could be explained by a modelled ocean–atmosphere feedback delaying the atmospheric reaction to solar activity variations up to a few years.

scholarly journals Evolving flood patterns in a Mediterranean region (1301–2012) and climatic factors – the case of Catalonia

2015 ◽  
Vol 19 (1) ◽  
pp. 465-483 ◽  
Author(s):  
A. Barrera-Escoda ◽  
M. C. Llasat
Keyword(s):  
Solar Activity ◽  
Mediterranean Region ◽  
General Circulation ◽  
Climatic Factors ◽  
Late Summer ◽  
Heavy Precipitation ◽  
Significant Rise ◽  
Flood Frequency ◽  
Quasi Biennial Oscillation ◽  
Flood Impacts

Abstract. Data on flood occurrence and flood impacts for the last seven centuries in the northeastern Iberian Peninsula have been analysed in order to characterise long-term trends, anomalous periods and their relationship with different climatic factors such as precipitation, general circulation and solar activity. Catastrophic floods (those that produce complete or partial destruction of infrastructure close to the river, and major damages in the overflowed area, including some zones away from the channels) do not present a statistically significant trend, whereas extraordinary floods (the channel is overflowed and some punctual severe damages can be produced in the infrastructures placed in the rivercourse or near it, but usually damages are slight) have seen a significant rise, especially from 1850 on, and were responsible for the total increase in flooding in the region. This rise can be mainly attributed to small coastal catchments, which have experienced a marked increase in developed land and population, resulting in changes in land use and greater vulnerability. Changes in precipitation alone cannot explain the variation in flood patterns, although a certain increase was shown in late summer–early autumn, when extraordinary floods are most frequently recorded. The relationship between the North Atlantic circulation and floods is not as strong, due to the important role of mesoscale factors in heavy precipitation in the northwest of the Mediterranean region. However, it can explain the variance to some extent, mainly in relation to the catastrophic floods experienced during the autumn. Solar activity has some impact on changes in catastrophic floods, with cycles related to the quasi-biennial oscillation (QBO) and the Gleissberg solar cycle. In addition, anomalous periods of high flood frequency in autumn generally occurred during periods of increased solar activity. The physical influence of the latter in general circulation patterns, the high troposphere and the stratosphere, has been analysed in order to ascertain its role in causing floods.

Characterizing large-scale circulation triggering heavy precipitation amounts over the northern French Alps

2020 ◽  
Author(s):  
Antoine Blanc ◽  
Juliette Blanchet ◽  
Jean-Dominique Creutin
Keyword(s):  
Large Scale ◽  
Western Europe ◽  
Heavy Precipitation ◽  
Geostrophic Wind ◽  
Time Step ◽  
French Alps ◽  
Circulation Patterns ◽  
Combined Use ◽  
Applied Meteorology ◽  
Low Dimensional

&lt;p&gt;&lt;span&gt;Large-scale circulations (LSCs) explain a significant part of Alpine precipitations. Characterizing circulations triggering heavy precipitation is usually done using weather-type classifications. A different characterization is implemented here, based on analogy using the atmospheric descriptors proposed in Blanchet et al 2018, 2019. These descriptors are both related to the dynamics of LSC and to their relative position in the atmospheric space. &lt;/span&gt;&lt;span&gt;This work is applied to the Is&amp;#232;re river catchment for the 1950-2011 period, considering a 3-&lt;/span&gt;&lt;span&gt;day time step. The 500 hPa and 1000 hPa geopotential heights covering part of the western Europe are used separately to represent LSC. Two analogy criteria are investigated for constructing the atmospheric descriptors, namely TWS and RMSE.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;Our results reveal that LSCs triggering heavy precipitation amounts correspond to strong geostrophic wind with quasi constant direction during the three days, corresponding to blocking situations in altitude. Moreover, those patterns of circulation are among the least singulars, and they show the highest degree of clustering in the atmospheric space. We interpret the latest results by the fact that heavy precipitation LSCs feature twin circulation patterns. In addition, the 500 hPa geopotential height appears to discriminate better heavy precipitation situations than the 1000 hPa one. Finally, our work points out the benefit of a combined use of TWS and RMSE. TWS gives information about the direction of geostrophic wind, while RMSE -combined with TWS- informs about its strength.&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Blanchet, J., Stalla, S., and Creutin, J.-D. (2018). Analogy of multi-day sequences of atmospheric circulation favoring large rainfall accumulation over the French Alps. Atmospheric Science Letters.&lt;/p&gt;&lt;p&gt;Blanchet, J., Creutin, J-D. &lt;span&gt;(2019). Modelling rainfall accumulations over several days in the French Alps using low-dimensional atmospheric predictors based on analogy. Journal of Applied Meteorology and Climatology.&lt;/span&gt;&lt;/p&gt;

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