Mesoscale Model Simulations of Three Heavy Precipitation Events in the Western Mediterranean Region

Abstract. The high-impact precipitation events that regularly affect the western Mediterranean coastal regions are still difficult to predict with the current prediction systems. Bearing this in mind, this paper focuses on the superensemble technique applied to the precipitation field. Encouraged by the skill shown by a previous multiphysics ensemble prediction system applied to western Mediterranean precipitation events, the superensemble is fed with this ensemble. The training phase of the superensemble contributes to the actual forecast with weights obtained by comparing the past performance of the ensemble members and the corresponding observed states. The non-hydrostatic MM5 mesoscale model is used to run the multiphysics ensemble. Simulations are performed with a 22.5 km resolution domain (Domain 1 in http://mm5forecasts.uib.es) nested in the ECMWF forecast fields. The period between September and December 2001 is used to train the superensemble and a collection of 19~MEDEX cyclones is used to test it. The verification procedure involves testing the superensemble performance and comparing it with that of the poor-man and bias-corrected ensemble mean and the multiphysic EPS control member. The results emphasize the need of a well-behaved training phase to obtain good results with the superensemble technique. A strategy to obtain this improved training phase is already outlined.

Download Full-text

Combined use of Raman lidar and DIAL measurements and MESO-NH model simulations for the characterization of complex water vapour field structures and their genesis: a case study from HyMeX-SOP 1

10.5194/egusphere-egu2020-16666 ◽

2020 ◽

Author(s):

Paolo Di Girolamo ◽

Marie-Noelle Bouin ◽

Cyrille Flamant ◽

Donato Summa ◽

Benedetto De Rosa

Keyword(s):

Water Vapour ◽

Heavy Precipitation ◽

Time Interval ◽

Mixing Ratio ◽

Raman Lidar ◽

Model Simulations ◽

Combined Use ◽

Geographical Regions ◽

Lidar Measurements ◽

Precipitation Events

As part of the Cevennes-Vivarais site, the University of Basilicata Raman lidar system BASIL was deployed in Candillargues and operated throughout the duration of HyMeX-SOP 1 (September-November 2012), providing high-resolution and accurate measurements, both in daytime and night-time, of atmospheric temperature, water vapour mixing ratio and particle backscattering and extinction coefficient at three wavelengths.Measurements carried out by BASIL on 28 September 2012 reveal a water vapour field characterized by a quite complex vertical structure. Reported measurements were run in the time interval between two consecutive heavy precipitation events, from 15:30 UTC on 28 September to 03:30 UTC on 29 September 2012. Throughout most of this observation period, lidar measurements reveal the presence of four distinct humidity layers.The present research effort aims at assessing the origin and transport path of the different humidity filaments observed by BASIL on this day. The analysis approach relies on the comparison between Raman lidar measurements and MESO-NH and NOAA-HYSPLIT model simulations. Back-trajectory analyses from MESO-NH reveal that air masses ending in Candillargues at different altitudes levels are coming and are originated from different geographical regions.The four distinct humidity layers observed by BASIL are also identified in the water vapour mixing ratio profiles collected by the air-borne DIAL LEANDRE 2 on-board of the French research aircraft ATR42. The exact correspondence, in terms of back-trajectories computation and water budget, between the humidity layers observed by BASIL and those identified in LEANDRE2 measurements has been verified based on a dedicated simulation effort.In the paper we also try to identify the presence of dry layers and cold pools and assess their role in the genesis of the mesoscale convective systems and the heavy precipitation events observed on 29 September 2012 based on the combined use of water vapour mixing ratio and temperature profile measurements from BASIL and water vapour mixing ratio profile measurements from LEANDRE 2, again supported by MESO-NH simulations.

Download Full-text

Heavy precipitation events over the Euro-Mediterranean region in a warmer climate: results from CMIP5 models

Regional Environmental Change ◽

10.1007/s10113-014-0712-y ◽

2014 ◽

Vol 16 (3) ◽

pp. 595-602 ◽

Cited By ~ 31

Author(s):

Enrico Scoccimarro ◽

Silvio Gualdi ◽

Alessio Bellucci ◽

Matteo Zampieri ◽

Antonio Navarra

Keyword(s):

Mediterranean Region ◽

Heavy Precipitation ◽

Cmip5 Models ◽

Precipitation Events

Download Full-text

Influence of submonthly air-sea coupling on heavy precipitation events in the Western Mediterranean basin

Quarterly Journal of the Royal Meteorological Society ◽

10.1002/qj.2717 ◽

2016 ◽

Vol 142 ◽

pp. 453-471 ◽

Cited By ~ 17

Author(s):

Ségolène Berthou ◽

Sylvain Mailler ◽

Philippe Drobinski ◽

Thomas Arsouze ◽

Sophie Bastin ◽

...

Keyword(s):

Mediterranean Basin ◽

Heavy Precipitation ◽

Western Mediterranean ◽

Western Mediterranean Basin ◽

Precipitation Events

Download Full-text

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

Earth System Dynamics Discussions ◽

10.5194/esdd-6-907-2015 ◽

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.

Download Full-text

AROME-WMED, a real-time mesoscale model designed for the HyMeX Special Observation Periods

Geoscientific Model Development Discussions ◽

10.5194/gmdd-8-1801-2015 ◽

2015 ◽

Vol 8 (2) ◽

pp. 1801-1856 ◽

Cited By ~ 12

Author(s):

N. Fourrié ◽

&Eacute;. Bresson ◽

M. Nuret ◽

C. Jany ◽

P. Brousseau ◽

...

Keyword(s):

Real Time ◽

Hydrological Cycle ◽

Mesoscale Model ◽

Weather Prediction ◽

Heavy Precipitation ◽

Western Mediterranean ◽

Western Mediterranean Basin ◽

Convective Scale ◽

Observation Instruments ◽

High Precipitation Events

Abstract. During autumn 2012 and winter 2013, two Special Observation Periods (SOPs) of the Hydrological cycle in the Mediterranean Experiment (HyMeX) took place. For the preparatory studies and to support the instrument deployment during the field campaign, a dedicated version of the operational convective-scale AROME-France model was developed: the AROME-WMED model. It covers the western Mediterranean basin with a 48 h forecast range. It provided real time analyses and forecasts which were sent daily to the HyMeX operational centre to forecast high precipitation events and to help decision makers on the deployment of observation instruments. This paper presents the main features of this numerical weather prediction system in terms of data assimilation and forecast. Some specific data of the HyMeX SOP were assimilated in real time. The forecast skill of the AROME-WMED is then assessed with objective scores and compared to the operational AROME-France model, for both autumn 2012 (5 September to 6 November 2012) and winter 2013 (1 February to 15 March 2013) SOPs. The overall performance of AROME-WMED is good and similar to those of AROME-France for the 0 to 30 h common forecast range. The 24 to 48 h forecast range is of course less accurate but remains useful for scheduling observation deployment. The characteristics of parameters such as precipitation, temperature or humidity, are illustrated by one heavy precipitation case study that occurred over the south of Spain.

Download Full-text

Performance of two cumulus convection parameterizations for two heavy precipitation events in the Western Mediterranean

Meteorology and Atmospheric Physics ◽

10.1007/bf01026633 ◽

1998 ◽

Vol 66 (3-4) ◽

pp. 197-214 ◽

Cited By ~ 2

Author(s):

R. Romero ◽

C. Ramis ◽

S. Alonso

Keyword(s):

Heavy Precipitation ◽

Western Mediterranean ◽

Cumulus Convection ◽

Precipitation Events

Download Full-text

The sequence of heavy precipitation and flash flooding of 12 and 13 September 2019 in eastern Spain. Part I: Mesoscale diagnostic and sensitivity analysis of precipitation

Journal of Hydrometeorology ◽

10.1175/jhm-d-20-0182.1 ◽

2021 ◽

Author(s):

Alejandro Hermoso ◽

Victor Homar ◽

Arnau Amengual

Keyword(s):

Heat Flux ◽

Latent Heat ◽

Latent Heat Flux ◽

Mediterranean Region ◽

Heavy Precipitation ◽

Western Mediterranean ◽

Moisture Distribution ◽

Flash Flooding ◽

The Mediterranean

AbstractThe Mediterranean region is frequently affected by heavy precipitation episodes and subsequent flash flooding. An exemplary case is the heavy precipitation episode that occurred in the regions of València, Murcia, and Almería (eastern Spain) on 12 and 13 September 2019. Observed rainfall amounts were close to 500 mm in 48 h, causing seven fatalities and estimated economical losses above 425 million EUR. This case exemplifies the challenging aspects of convective-scale forecasting in the Mediterranean region, with kilometer-resolution meteorological fields required over long forecast spans. Understanding the key mesoscale factors acting on the triggering, location, and intensity of the convective systems responsible for extreme accumulations is essential to gain insight into these episodes and contribute towards their accurate hydrometeorological forecasting. Mesoscale diagnosis suggests that local and distant orography, together with air-sea fluxes, were instrumental in developing convection and intensifying precipitation rate. Sensitivity experiments confirm the role of orography in organizing the cyclonic flow over the southeast part of the western Mediterranean, and also acting as a convection triggering mechanism. Furthermore, results highlight the role of latent heat flux from the Mediterranean Sea in enhancing convective instability at lower levels and moistening the environment. These moist feeding flows substantially contribute to increasing precipitation rates. Such high sensitivity to environmental moisture distribution naturally propagates to the sea surface temperature which, by means of sensible and latent heat flux exchanges, dominated the evolution of convective activity for the 12-13 September 2019 episode.

Download Full-text

Ensemble generation strategies for the short-range forecast of flash floods: the 12-13 September 2019 event in Eastern Spain

10.5194/egusphere-egu2020-10453 ◽

2020 ◽

Author(s):

Alejandro Hermoso ◽

Victor Homar ◽

Arnau Amengual

Keyword(s):

Mediterranean Region ◽

Short Range ◽

Dynamical Downscaling ◽

Mesoscale Model ◽

Heavy Precipitation ◽

Ensemble Prediction ◽

Economic Losses ◽

Small Scale ◽

Flash Flooding ◽

Ensemble Generation

The Mediterranean region is frequently affected by heavy precipitation and flash flooding during the extended warm season. A precise meteorological forecast of socially relevant aspects of these phenomena such as location, timing and intensity is crucial to prevent personal and material losses. However, forecasting these aspects becomes extremely challenging due to small-scale processes involved in the triggering, development and subsequent evolution of convective systems.&#160;On 12 and 13 September 2019 widespread flash flooding caused devastating effects across Murcia and Valencia, eastern Spain. Seven fatalities were reported, hundreds of homes were flooded and economic losses were estimated at 200 M&#8364;. The performance of various ensemble generation strategies for short-range convection-permitting ensemble prediction systems (EPS) are evaluated for this episode. Different sources of error are coped by the implemented ensemble generation approaches. &#160;Uncertainty in the initial and lateral boundary conditions uncertainty is sampled in two ways: (i) the dynamical downscaling of the ECMWF global EPS and, (ii) a new tailored breeding technique that accounts for perturbations across the multiple scales of interest for short-range forecasting. Additionally, errors in mesoscale model formulation are encompassed by combining different parameterization schemes and stochastic physics.&#160;This study contributes to the identification of the most relevant sources of uncertainty hampering an accurate spatial and temporal forecasting of heavy precipitation resulting in flash flooding over the Spanish Mediterranean region. These cutting-edge EPS can contribute to implement more reliable and effective hydrometeorological prediction chains with lead times up to 24 h, providing a valuable support to civil protection and emergency management authorities.

Download Full-text