scholarly journals Precipitation extremes in the Mediterranean region and associated upper-level synoptic-scale flow structures

2015 ◽  
Vol 47 (5-6) ◽  
pp. 1925-1941 ◽  
Author(s):  
Andrea Toreti ◽  
Paraskevi Giannakaki ◽  
Olivia Martius
Keyword(s):  
Mediterranean Region ◽  
Precipitation Extremes ◽  
Flow Structures ◽  
Synoptic Scale ◽  
The Mediterranean ◽  
Upper Level

scholarly journals Comparison between the Large-Scale Environments of Moderate and Intense Precipitating Systems in the Mediterranean Region

2009 ◽  
Vol 137 (11) ◽  
pp. 3933-3959 ◽  
Author(s):  
Beatriz M. Funatsu ◽  
Chantal Claud ◽  
Jean-Pierre Chaboureau
Keyword(s):  
Mediterranean Region ◽  
Large Scale ◽  
Deep Convection ◽  
Extreme Rainfall ◽  
Convective Precipitation ◽  
Target Area ◽  
Weather Forecasts ◽  
Microwave Sounding ◽  
The Mediterranean ◽  
Upper Level

Abstract A characterization of the large-scale environment associated with precipitating systems in the Mediterranean region, based mainly on NOAA-16 Advanced Microwave Sounding Unit (AMSU) observations from 2001 to 2007, is presented. Channels 5, 7, and 8 of AMSU-A are used to identify upper-level features, while a simple and tractable method, based on combinations of channels 3–5 of AMSU-B and insensitive to land–sea contrast, was used to identify precipitation. Rain occurrence is widespread over the Mediterranean in wintertime while reduced or short lived in the eastern part of the basin in summer. The location of convective precipitation shifts from mostly over land from April to August, to mostly over the sea from September to December. A composite analysis depicting large-scale conditions, for cases of either rain alone or extensive areas of deep convection, is performed for selected locations where the occurrence of intense rainfall was found to be important. In both cases, an upper-level trough is seen to the west of the target area, but for extreme rainfall the trough is narrower and has larger amplitude in all seasons. In general, these troughs are also deeper for extreme rainfall. Based on the European Centre for Medium-Range Weather Forecasts operational analyses, it was found that sea surface temperature anomalies composites for extreme rainfall are often about 1 K warmer, compared to nonconvective precipitation conditions, in the vicinity of the affected area, and the wind speed at 850 hPa is also stronger and usually coming from the sea.

scholarly journals Two case studies of severe storms in the Mediterranean using AMSU

2007 ◽  
Vol 12 ◽  
pp. 19-26 ◽  
Author(s):  
B. M. Funatsu ◽  
C. Claud ◽  
J.-P. Chaboureau
Keyword(s):  
Mediterranean Region ◽  
Detection Method ◽  
Precipitation Data ◽  
Severe Storms ◽  
Rainfall Events ◽  
Microwave Sounding Unit ◽  
Microwave Sounding ◽  
The Mediterranean ◽  
Upper Level ◽  
Good Agreement

Abstract. Mediterranean storms and their associated upper level features are diagnosed here using Advanced Microwave Sounding Unit (AMSU) observations. AMSU-A channel 8 is used to identify upper-level intrusions of stratospheric air, which are often present upstream of heavy precipitating areas, while a combination of AMSU-B channels 3 and 5 is chosen to discriminate moderate to heavily precipitating areas. This precipitation detection method provides results that are in good agreement with TRMM rainfall product and independent ground-based precipitation data. These tools allow us to follow the concomitant evolution of two severe rainfall events in the Mediterranean region and associated upper-level features.

scholarly journals Non-susceptible landslide areas in Italy and in the Mediterranean region

2014 ◽  
Vol 2 (4) ◽  
pp. 2813-2849
Author(s):  
I. Marchesini ◽  
F. Ardizzone ◽  
M. Alvioli ◽  
M. Rossi ◽  
F. Guzzetti
Keyword(s):  
Mediterranean Sea ◽  
Linear Model ◽  
Landslide Susceptibility ◽  
Mediterranean Region ◽  
Census Data ◽  
Mediterranean Area ◽  
Moving Window ◽  
Synoptic Scale ◽  
Srtm Dem ◽  
The Mediterranean

Abstract. We used landslide information for 13 study areas in Italy and morphometric information obtained from the 3 arc-second SRTM DEM to determine areas where landslide susceptibility is expected to be null or negligible in Italy, and in the landmasses surrounding the Mediterranean Sea. The morphometric information consisted in the local terrain slope computed in a square 3 × 3 cell moving window, and in the regional relative relief computed in a circular 15 × 15 cell moving window. We tested three different models to determine the non-susceptible landslide areas, including a linear model (LR), a quantile linear model (QLR), and a quantile non-linear model (QNL). We tested the performance of the three models using independent landslide information represented by the Italian Landslide Inventory (Inventario Fenomeni Franosi in Italia – IFFI). Best results were obtained using the QNL model. The corresponding zonation of non-susceptible landslide areas was intersected in a GIS with geographical census data for Italy. The result allowed determining that 57.5% of the population of Italy (in 2001) was located in areas where landslide susceptibility is expected to be null or negligible, and that the remaining 42.5% was located in areas where some landslide susceptibility is expected. We applied the QNL model to the landmasses surrounding the Mediterranean Sea, and we tested the synoptic non-susceptibility zonation using independent landslide information for three study areas in Spain. Results proved that the QNL model was capable of determining where landslide susceptibility is expected to be negligible in the Mediterranean area. We expect our results to be applicable in similar study areas, facilitating the identification of non-susceptible and susceptible landslide areas, at the synoptic scale.

scholarly journals Cyclogenesis in the Mediterranean basin: a diagnosis using synoptic-dynamic anomalies

2009 ◽  
Vol 9 (3) ◽  
pp. 957-965 ◽  
Author(s):  
M. Kaspar ◽  
M. Müller
Keyword(s):  
Central Europe ◽  
Mediterranean Region ◽  
Frontal Zone ◽  
Western Mediterranean ◽  
Cumulative Distribution ◽  
Diagnostic Study ◽  
Synoptic Scale ◽  
Vertical Coupling ◽  
The Mediterranean ◽  
Heavy Rains

Abstract. This work deals with the hypothesis that synoptically-driven heavy rains in the Mediterranean region are connected with the occurrence of synoptic-dynamic anomalies. We investigate this hypothesis by conducting a diagnostic study of a cyclogenesis event from 18–21 July 2001. Cyclogenesis started over the western Mediterranean Sea and was triggered by the approach of a pre-existing upper trough over a lower frontal zone. The event was first accompanied by heavy convective rains in northern Italy and later by heavy, widespread and steady rains of non-convective character in Central Europe. Using re-analyses from the database ERA-40, we evaluate the synoptic-dynamic anomalies by the cumulative distribution function relatively to July–August area-related climatology over the reference period from 1958 to 2002. For the duration of cyclogenesis, we detect significant anomalies associated with the processes that support the completion of vertical coupling between the lower frontal zone and the upper vorticity maximum. The periods of heavy rains in both the Mediterranean region and Central Europe were characterised by the occurrence of anomalies that created synoptic-scale conditions favourable for triggering and sustaining heavy rains. Although these anomalies were somewhat weaker in the period of heavy rains in Central Europe than in the Mediterranean region, the analysis of their spatio-temporal correspondence over the reference rainfall events in the Czech Republic shows that they are typical of heavy rains there. Due to the relatively high variability of the causal synoptic-scale conditions, this study would benefit post-processing procedures aimed at improving warning about this hazardous weather phenomenon to further investigate which anomalies generally occur during synoptically-driven heavy rains in the Mediterranean region and the strengths of these anomalies.

scholarly journals Synoptic-scale drivers of the Mistral wind: link to Rossby wave life cycles and seasonal variability

2021 ◽  
Author(s):  
Yonatan Givon ◽  
Douglas Keller Jr. ◽  
Romain Pennel ◽  
Philippe Drobinski ◽  
Shira Raveh-Rubin
Keyword(s):  
Rossby Wave ◽  
Clustering Algorithm ◽  
Life Cycles ◽  
Extreme Weather Events ◽  
Turbulent Heat ◽  
Synoptic Scale ◽  
Low Level ◽  
Lee Cyclogenesis ◽  
The Mediterranean ◽  
Upper Level

Abstract. The mistral is a northerly low level jet blowing through the Rhône valley in southern France, and down to the Gulf of Lions. It is co-located with the cold sector of a low level lee-cyclone in the Gulf of Genoa, behind an upper level trough north of the Alps. The mistral wind has long been associated with extreme weather events in the Mediterranean, and while extensive research focused on the low-tropospheric mistral and lee-cyclogenesis, the different upper-tropospheric large- and synoptic-scale settings involved in producing the mistral wind are not generally known. Here, the isentropic potential vorticity (PV) structures governing the occurrence of the mistral wind are classified using a self-organizing map (SOM) clustering algorithm. Based upon a 36-year (1981–2016) mistral database and daily ERA-Interim isentropic PV data, 16 distinct mistral-associated PV structures emerge. Each classified flow pattern corresponds to a different type or stage of the Rossby wave life-cycle, from broad troughs, thin PV streamers, to distinguished cut-offs. Each of these PV patterns exhibit a distinct surface impact in terms of the surface cyclone, surface turbulent heat fluxes, wind, temperature and precipitation. A clear seasonal separation between the clusters is evident and transitions between the clusters correspond to different Rossby wave-breaking processes. This analysis provides a new perspective on the variability of the mistral, and of the Genoa lee-cyclogenesis in general, linking the upper-level PV structures to their surface impact over Europe, the Mediterranean and north Africa.

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