Review Article: Atmospheric conditions inducing extreme precipitation over the eastern and western Mediterranean

Dayan, Uri; Nissen, Katrin M.; Ulbrich, Uwe

doi:10.5194/nhess-15-2525-2015

Cited by 95 publications

(61 citation statements)

References 145 publications

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“…Intensities and duration of extreme events differ dramatically within the study area, with the relative frequency of high rainfall intensities increasing as the mean annual precipitation decreases (Marra et al, 2017;Marra and Morin, 2015;Morin et al, 2009;Sharon and Kutiel, 1986). Most intense rainfall episodes over the study area, and the EM in general, are associated with the cold fronts of mid-latitude lows: the Cyprus low -a Mediterranean low located around Cyprus, and the Syrian low -a well-developed Mediterranean low located over Syria (Dayan et al, 2015;Dayan and Morin, 2006;Goldreich, 2003;Kahana et al, 2002). The region is also affected by more localized convective showers associated with the Active Red Sea trough (ARST), a surface low-pressure trough extending from eastern Africa along the Red Sea towards the Middle East in its active phase (Ashbel, 1938).…”

Section: Climatementioning

confidence: 92%

Convective rainfall in a dry climate: relations with synoptic systems and flash-flood generation in the Dead Sea region

Belachsen

Marra

Peleg

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. Spatiotemporal patterns of rainfall are important characteristics that influence runoff generation and flashflood magnitude and require high-resolution measurements to be adequately represented. This need is further emphasized in arid climates, where rainfall is scarce and highly variable. In this study, 24 years of corrected and gaugeadjusted radar rainfall estimates are used to (i) identify the spatial structure and dynamics of convective rain cells in a dry climate region in the Eastern Mediterranean, (ii) to determine their climatology, and (iii) to understand their relation with the governing synoptic systems and with flashflood generation. Rain cells are extracted using a segmentation method and a tracking algorithm, and are clustered into three synoptic patterns according to atmospheric variables from the ERA-Interim reanalysis. On average, the cells are about 90 km 2 in size, move 13 m s −1 from west to east, and live for 18 min. The Cyprus low accounts for 30 % of the events, the low to the east of the study region for 44 %, and the Active Red Sea Trough for 26 %. The Active Red Sea Trough produces shorter rain events composed of rain cells with higher rain intensities, longer lifetime, smaller area, and lower velocities. The area of rain cells is positively correlated with topographic height. The number of cells is negatively correlated with the distance from the shoreline. Rain-cell intensity is negatively correlated with mean annual precipitation. Flash-flood-related events are dominated by rain cells of large size, low velocity, and long lifetime that move downstream with the main axis of the catchments. These results can be further used for stochastic simulations of convective rain storms and serve as input for hydrological models and for flash-flood nowcasting systems.

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Section: Climatementioning

confidence: 92%

Convective rainfall in a dry climate: relations with synoptic systems and flash-flood generation in the Dead Sea region

Belachsen

Marra

Peleg

et al. 2017

Hydrol. Earth Syst. Sci.

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“…Rainfall over the Mediterranean areas is generally brought by cold fronts and post-frontal systems, associated with mid-latitude cyclones (Goldreich, 2003;Peleg and Morin, 2012), and by Syrian low and active Red Sea Trough, occasionally correlated with flash floods, in the semiarid and arid climates (Dayan et al, 2001;Dayan and Morin, 2006;Kahana et al, 2002;de Vries et al, 2013). On rare occasions the subtropical jet, or tropical plume, brings widespread rainfall over the whole region (Dayan and Morin, 2006;Kahana et al, 2002;Rubin et al, 2007;Tubi and Dayan, 2014;Dayan et al, 2015). Important gradients have been reported also for the climatology of extreme rainfall.…”

Section: Mediterraneanmentioning

confidence: 99%

Intensity–duration–frequency curves from remote sensing rainfall estimates: comparing satellite and weather radar over the eastern Mediterranean

Marra

Morin

Peleg

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. Intensity-duration-frequency (IDF) curves are widely used to quantify the probability of occurrence of rainfall extremes. The usual rain gauge-based approach provides accurate curves for a specific location, but uncertainties arise when ungauged regions are examined or catchment-scale information is required. Remote sensing rainfall records, e.g. from weather radars and satellites, are recently becoming available, providing high-resolution estimates at regional or even global scales; their uncertainty and implications on water resources applications urge to be investigated. This study compares IDF curves from radar and satellite (CMORPH) estimates over the eastern Mediterranean (covering Mediterranean, semiarid, and arid climates) and quantifies the uncertainty related to their limited record on varying climates. We show that radar identifies thicker-tailed distributions than satellite, in particular for short durations, and that the tail of the distributions depends on the spatial and temporal aggregation scales. The spatial correlation between radar IDF and satellite IDF is as high as 0.7 for 2-5-year return period and decreases with longer return periods, especially for short durations. The uncertainty related to the use of short records is important when the record length is comparable to the return period ( ∼ 50, ∼ 100, and ∼ 150 % for Mediterranean, semiarid, and arid climates, respectively). The agreement between IDF curves derived from different sensors on Mediterranean and, to a good extent, semiarid climates, demonstrates the potential of remote sensing datasets and instils confidence on their quantitative use for ungauged areas of the Earth.

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“…Dayan et al, 2015). The storm tracks of these cyclones travelling from the North Atlantic to Europe depend on the direction and strength of the westerly winds that are controlled by the relative positions of the permanent Azores high and Icelandic low.…”

Section: Mesoscale Modelsmentioning

confidence: 99%

Overview of the first HyMeX special observation period over Croatia

Ivančan-Picek

Tudor

Horvath

et al. 2016

Nat. Hazards Earth Syst. Sci.

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Abstract. The HYdrological cycle in the Mediterranean EXperiment (HyMeX) is intended to improve the capabilities of predicting high-impact weather events. Within its framework, the aim of the first special observation period (SOP1), 5 September to 6 November 2012, was to study heavy precipitation events and flash floods. Here, we present high-impact weather events over Croatia that occurred during SOP1. Particular attention is given to eight intense observation periods (IOPs), during which high precipitation occurred over the eastern Adriatic and Dinaric Alps. During the entire SOP1, the operational model forecasts generally well represented medium intensity precipitation, but heavy precipitation was frequently underestimated by the ALADIN model at an 8 km grid spacing and was overestimated at a higher resolution (2 km grid spacing). During IOP2, intensive rainfall occurred over a wider area around the city of Rijeka in the northern Adriatic. The short-range maximum rainfall totals were the largest ever recorded at the Rijeka station since the beginning of measurements in 1958. The rainfall amounts measured in intervals of 20, 30 and 40 min were exceptional, with return periods that exceeded a thousand, a few hundred and one hundred years, respectively. The operational precipitation forecast using the ALADIN model at an 8 km grid spacing provided guidance regarding the event but underestimated the rainfall intensity. An evaluation of numerical sensitivity experiments suggested that the forecast was slightly enhanced by improving the initial conditions through variational data assimilation. The operational non-hydrostatic run at a 2 km grid spacing using a configuration with the ALARO physics package further improved the forecast. This article highlights the need for an intensive observation period in the future over the Adriatic region to validate the simulated mechanisms and improve numerical weather predictions via data assimilation and model improvements in descriptions of microphysics and air-sea interactions.

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Review Article: Atmospheric conditions inducing extreme precipitation over the eastern and western Mediterranean

Cited by 95 publications

References 145 publications

Convective rainfall in a dry climate: relations with synoptic systems and flash-flood generation in the Dead Sea region

Convective rainfall in a dry climate: relations with synoptic systems and flash-flood generation in the Dead Sea region

Intensity–duration–frequency curves from remote sensing rainfall estimates: comparing satellite and weather radar over the eastern Mediterranean

Overview of the first HyMeX special observation period over Croatia

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