Predictability of precipitation extremes over the Mediterranean

2020 ◽  
Author(s):  
Ignazio Giuntoli ◽  
Federico Fabiano ◽  
Susanna Corti
Keyword(s):  
Extreme Precipitation ◽  
Winter Season ◽  
Seasonal Prediction ◽  
Reanalysis Data ◽  
Economic Activities ◽  
Weather Regimes ◽  
Extreme Precipitation Events ◽  
The Mediterranean ◽  
Prediction Systems ◽  
Precipitation Events

<p>Intense precipitations events are associated with impacts like damages to infrastructures, economic activities, agricultural crops, power production and society in general. The ability to predict extreme precipitation events months in advance is therefore of great value in densely populated areas like the Mediterranean and may be achieved using seasonal prediction systems like the Copernicus Climate Change Services (C3S) suite of models. Using weather regimes (WRs) from 500 hPa geopotential heights over the Mediterranean the two main objectives of this study are: first to identify how these regimes are linked to extreme precipitation events over the region using reanalysis data; and second to assess the ability of the C3S models in reproducing/predicting these extreme events. We identify four weather regimes for the winter season (DJF) describing the atmospheric circulation in the Mediterranean using the 1993-2016 period as reference, i.e. maximum availability of C3S hindcasts. We thus provide an assessment of the models’s ability in predicting extreme precipitation over the Mediterranean having quantified how daily precipitation anomalies are associated to each WR.</p>

A novel method to identify subseasonal clustering episodes of extreme precipitation events and their contribution to large accumulations

2021 ◽  
Author(s):  
Jérôme Kopp ◽  
Pauline Rivoire ◽  
S. Mubashshir Ali ◽  
Yannick Barton ◽  
Olivia Martius
Keyword(s):  
Time Scales ◽  
Extreme Precipitation ◽  
Large Scale ◽  
Time Window ◽  
Heat Waves ◽  
Reanalysis Data ◽  
Data Set ◽  
Temporal Clustering ◽  
Extreme Precipitation Events ◽  
Precipitation Events

<p>Temporal clustering of extreme precipitation events on subseasonal time scales is a type of compound event, which can cause large precipitation accumulations and lead to floods. We present a novel count-based procedure to identify subseasonal clustering of extreme precipitation events. Furthermore, we introduce two metrics to characterise the frequency of subseasonal clustering episodes and their relevance for large precipitation accumulations. The advantage of this approach is that it does not require the investigated variable (here precipitation) to satisfy any specific statistical properties. Applying this methodology to the ERA5 reanalysis data set, we identify regions where subseasonal clustering of annual high precipitation percentiles occurs frequently and contributes substantially to large precipitation accumulations. Those regions are the east and northeast of the Asian continent (north of Yellow Sea, in the Chinese provinces of Hebei, Jilin and Liaoning; North and South Korea; Siberia and east of Mongolia), central Canada and south of California, Afghanistan, Pakistan, the southeast of the Iberian Peninsula, and the north of Argentina and south of Bolivia. Our method is robust with respect to the parameters used to define the extreme events (the percentile threshold and the run length) and the length of the subseasonal time window (here 2 – 4 weeks). The procedure could also be used to identify temporal clustering of other variables (e.g. heat waves) and can be applied on different time scales (e.g. for drought years). <span>For a complementary study on the subseasonal clustering of European extreme precipitation events and its relationship to large-scale atmospheric drivers, please refer to Barton et al.</span></p>

scholarly journals Characterization of Extreme Precipitation Events in the Pyrenees. From the Local to the Synoptic Scale.

2021 ◽  
Author(s):  
Marc Lemus-Canovas ◽  
Joan-A. Lopez-Bustins ◽  
Javier Martín-Vide ◽  
Amar Halifa-Marin ◽  
Damián Insua-Costa ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Synoptic Scale ◽  
Air Mass ◽  
Rain Gauges ◽  
Eastern Pyrenees ◽  
Extreme Precipitation Events ◽  
Mountain Systems ◽  
The Mediterranean ◽  
Precipitation Events ◽  
Western Pyrenees

Mountain systems within the Mediterranean region, e.g. the Pyrenees, are very sensitive to climate change. In the present study, we quantified the magnitude of extreme precipitation events and the number of days with torrential precipitation (daily precipitation ≥ 100 mm) in all the rain gauges available in the Pyrenees for the 1981-2015 period, analyzing the contribution of the synoptic scale in this type of events. The easternmost (under the Mediterranean influence) and north-westernmost (under Atlantic influence) areas of the Pyrenees registered the highest number of torrential events. The heaviest events are expected in the eastern part, i.e. 400 mm day-1 for a return period of 200 years. Northerly advections over the Iberian Peninsula, which present a low zonal index, i.e. im-plying a stronger meridional component, give rise to torrential events over the western Pyrenees; and easterly advections favour extreme precipitation over the eastern Pyrenees. The air mass travels a long way, from the east coast of North America, bringing heavy rainfall to the western Pyrenees. In the case of the torrential events over the eastern Pyrenees, the air mass causing the events in these areas is very short and originates in the Mediterranean Basin. The NAO index has no influence upon the occurrence of torrential events in the Pyrenees, but these events are closely related to certain Mediterranean teleconnections such as the WeMO

scholarly journals North American extreme precipitation events and related large-scale meteorological patterns: a review of statistical methods, dynamics, modeling, and trends

2019 ◽  
Vol 53 (11) ◽  
pp. 6835-6875 ◽  
Author(s):  
Mathew Barlow ◽  
William J. Gutowski ◽  
John R. Gyakum ◽  
Richard W. Katz ◽  
Young-Kwon Lim ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Large Scale ◽  
Climate Models ◽  
Early Stage ◽  
Reanalysis Data ◽  
Model Representation ◽  
Dynamics Modeling ◽  
Considerable Uncertainty ◽  
Extreme Precipitation Events ◽  
Precipitation Events

Abstract This paper surveys the current state of knowledge regarding large-scale meteorological patterns (LSMPs) associated with short-duration (less than 1 week) extreme precipitation events over North America. In contrast to teleconnections, which are typically defined based on the characteristic spatial variations of a meteorological field or on the remote circulation response to a known forcing, LSMPs are defined relative to the occurrence of a specific phenomenon—here, extreme precipitation—and with an emphasis on the synoptic scales that have a primary influence in individual events, have medium-range weather predictability, and are well-resolved in both weather and climate models. For the LSMP relationship with extreme precipitation, we consider the previous literature with respect to definitions and data, dynamical mechanisms, model representation, and climate change trends. There is considerable uncertainty in identifying extremes based on existing observational precipitation data and some limitations in analyzing the associated LSMPs in reanalysis data. Many different definitions of “extreme” are in use, making it difficult to directly compare different studies. Dynamically, several types of meteorological systems—extratropical cyclones, tropical cyclones, mesoscale convective systems, and mesohighs—and several mechanisms—fronts, atmospheric rivers, and orographic ascent—have been shown to be important aspects of extreme precipitation LSMPs. The extreme precipitation is often realized through mesoscale processes organized, enhanced, or triggered by the LSMP. Understanding of model representation, trends, and projections for LSMPs is at an early stage, although some promising analysis techniques have been identified and the LSMP perspective is useful for evaluating the model dynamics associated with extremes.

The role of the export of tropical moisture into midlatitudes for extreme precipitation events in the Mediterranean region

2014 ◽  
Vol 121 (3-4) ◽  
pp. 499-515 ◽  
Author(s):  
Simon O. Krichak ◽  
Joseph Barkan ◽  
Joseph S. Breitgand ◽  
Silvio Gualdi ◽  
Steven B. Feldstein
Keyword(s):  
Extreme Precipitation ◽  
Mediterranean Region ◽  
Extreme Precipitation Events ◽  
The Mediterranean ◽  
Tropical Moisture ◽  
Precipitation Events

scholarly journals Discussing the role of tropical and subtropical moisture sources in extreme precipitation events in the Mediterranean region from a climate change perspective

2015 ◽  
Vol 3 (6) ◽  
pp. 3983-4005 ◽  
Author(s):  
S. O. Krichak ◽  
S. B. Feldstein ◽  
P. Alpert ◽  
S. Gualdi ◽  
E. Scoccimarro ◽  
...  
Keyword(s):  
Climate Change ◽  
Extreme Precipitation ◽  
Mediterranean Region ◽  
Extreme Weather Events ◽  
Recent Past ◽  
Atmospheric Rivers ◽  
Extreme Precipitation Events ◽  
The Mediterranean ◽  
Precipitation Events

Abstract. Extreme precipitation events in the Mediterranean region during the cool season are strongly affected by the export of moist air from tropical and subtropical areas into the extratropics. The aim of this paper is to present a discussion of the major research efforts on this subject and to formulate a summary of our understanding of this phenomenon, along with its recent past trends from a climate change perspective. The issues addressed are: a discussion of several case studies; the origin of the air moisture and the important role of atmospheric rivers for fueling the events; the mechanism responsible for the intensity of precipitation during the events, and the possible role of global warming in recent past trends in extreme weather events over the Mediterranean region.

scholarly journals Contribution of Moisture from Mediterranean Sea to Extreme Precipitation Events over Danube River Basin

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1182 ◽  
Author(s):  
Danica Ciric ◽  
Raquel Nieto ◽  
Alexandre Ramos ◽  
Anita Drumond ◽  
Luis Gimeno
Keyword(s):  
Mediterranean Sea ◽  
River Basin ◽  
Extreme Events ◽  
Extreme Precipitation ◽  
Extreme Event ◽  
Danube River ◽  
Extreme Precipitation Events ◽  
The Mediterranean ◽  
Danube River Basin ◽  
Precipitation Events

In the most recent decades, central Europe and the Danube River Basin area have been affected by an increase in the frequency and intensity of extreme daily rainfall, which has resulted in the more frequent occurrence of significant flood events. This study characterised the link between moisture from the Mediterranean Sea and extreme precipitation events, with varying lengths that were recorded over the Danube River basin between 1981 and 2015, and ranked the events with respect to the different time scales. The contribution of the Mediterranean Sea to the detected extreme precipitation events was then estimated using the Lagrangian FLEXPART dispersion model. Experiments were modelled in its forward mode, and particles leaving the Mediterranean Sea were tracked for a period of time determined with respect to the length of the extreme event. The top 100 extreme events in the ranking with durations of 1, 3, 5, 7, and 10 days were analysed, and it was revealed that most of these events occurred in the winter. For extreme precipitation, positive anomalies of moisture support from the Mediterranean were found to be in the order of 80% or more, but this support reached 100% in summer and spring. The results show that extreme precipitation events with longer durations are more influenced by the extreme Mediterranean anomalous moisture supply than those with shorter lengths. However, it is during shorter events when the Mediterranean Sea contributes higher amounts of moisture compared with its climatological mean values; for longer events, this contribution decreases progressively (but still doubles the climatological moisture contribution from the Mediterranean Sea). Finally, this analysis provides evidence that the optimum time period for accumulated moisture to be modelled by the Lagrangian model is that for which the extreme event is estimated. In future studies, this fine characterisation could assist in modelling moisture contributions from sources in relation to individual extreme events.

scholarly journals Characterisation of Extreme Precipitation Events in the Pyrenees: From the Local to the Synoptic Scale

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 665
Author(s):  
Marc Lemus-Canovas ◽  
Joan Albert Lopez-Bustins ◽  
Javier Martín-Vide ◽  
Amar Halifa-Marin ◽  
Damián Insua-Costa ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Western Mediterranean ◽  
Synoptic Scale ◽  
Air Mass ◽  
The North ◽  
Eastern Pyrenees ◽  
Extreme Precipitation Events ◽  
The Mediterranean ◽  
Precipitation Events ◽  
Western Pyrenees

Mountain systems within the Mediterranean region, e.g., the Pyrenees, are very sensitive to climate change. In the present study, we quantified the magnitude of extreme precipitation events and the number of days with torrential precipitation (daily precipitation ≥ 100 mm) in all the rain gauges available in the Pyrenees for the 1981–2015 period, analyzing the contribution of the synoptic scale in this type of event. The easternmost (under Mediterranean influence) and north-westernmost (under Atlantic influence) areas of the Pyrenees registered the highest number of torrential events. The heaviest events are expected in the eastern part, i.e., 400 mm day−1 for a return period of 200 years. Northerly advections over the Iberian Peninsula, which present a low zonal index, i.e., implying a stronger meridional component, give rise to torrential events over the western Pyrenees; and easterly advections favour extreme precipitation over the eastern Pyrenees. The air mass travels a long way, from the east coast of North America, bringing heavy rainfall to the western Pyrenees. In the case of the torrential events over the eastern Pyrenees, the trajectory of the air mass causing the events in these areas is very short and originates in the Mediterranean Basin. The North Atlantic Oscillation (NAO) index has no influence upon the occurrence of torrential events in the Pyrenees, but these events are closely related to certain Mediterranean teleconnections such as the Western Mediterranean Oscillation (WeMO).

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