scholarly journals Heavy Precipitation Systems in Calabria Region (Southern Italy): High-Resolution Observed Rainfall and Large-Scale Atmospheric Pattern Analysis

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1468 ◽  
Author(s):  
Aldo Greco ◽  
Davide Luciano De Luca ◽  
Elenio Avolio
Keyword(s):  
High Resolution ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Southern Italy ◽  
Early Warning Systems ◽  
Reanalysis Dataset ◽  
Rainfall Events ◽  
Calabria Region ◽  
Depth Analysis ◽  
Heavy Rainfall Events

An in-depth analysis of historical heavy rainfall fields clearly constitutes an important aspect in many related topics: as examples, mesoscale models for early warning systems and the definition of design event scenarios can be improved, with the consequent upgrading in the prediction of induced phenomena (mainly floods and landslides) into specific areas of interest. With this goal, in this work the authors focused on Calabria region (southern Italy) and classified the main precipitation systems through the analysis of selected heavy rainfall events from high resolution rain gauge network time series. Moreover, the authors investigated the relationships among the selected events and the main synoptic atmospheric patterns derived by the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 Reanalysis dataset, in order to assess the possible large-scale scenarios which can induce heavy rainfall events in the study area. The obtained results highlighted: (i) the importance of areal reduction factors, rainfall intensities and amounts in order to discriminate the investigated precipitations systems for the study area; (ii) the crucial role played by the position of the averaged low-pressure areas over the Mediterranean for the synoptic systems, and by low-level temperature for the convective systems.

scholarly journals Extreme Floods in the Eastern Part of Europe: Large-Scale Drivers and Associated Impacts

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1122
Author(s):  
Monica Ionita ◽  
Viorica Nagavciuc
Keyword(s):  
Water Vapor ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Flood Events ◽  
Rainfall Events ◽  
Catchment Areas ◽  
Large Scale Atmospheric Circulation ◽  
Heavy Rainfall Events

The role of the large-scale atmospheric circulation in producing heavy rainfall events and floods in the eastern part of Europe, with a special focus on the Siret and Prut catchment areas (Romania), is analyzed in this study. Moreover, a detailed analysis of the socio-economic impacts of the most extreme flood events (e.g., July 2008, June–July 2010, and June 2020) is given. Analysis of the largest flood events indicates that the flood peaks have been preceded up to 6 days in advance by intrusions of high Potential Vorticity (PV) anomalies toward the southeastern part of Europe, persistent cut-off lows over the analyzed region, and increased water vapor transport over the catchment areas of Siret and Prut Rivers. The vertically integrated water vapor transport prior to the flood peak exceeds 300 kg m−1 s−1, leading to heavy rainfall events. We also show that the implementation of the Flood Management Plan in Romania had positive results during the 2020 flood event compared with the other flood events, when the authorities took several precaution measurements that mitigated in a better way the socio-economic impact and risks of the flood event. The results presented in this study offer new insights regarding the importance of large-scale atmospheric circulation and water vapor transport as drivers of extreme flooding in the eastern part of Europe and could lead to a better flood forecast and flood risk management.

scholarly journals 2DVD Data Revisited: Multifractal Insights into Cuts of the Spatiotemporal Rainfall Process

2015 ◽  
Vol 16 (2) ◽  
pp. 548-562 ◽  
Author(s):  
Auguste Gires ◽  
Ioulia Tchiguirinskaia ◽  
Daniel Schertzer ◽  
Alexis Berne
Keyword(s):  
Time Series ◽  
High Resolution ◽  
Empirical Evidence ◽  
Heavy Rainfall ◽  
Resolution Time ◽  
Time Step ◽  
Measuring Device ◽  
Rainfall Events ◽  
Heavy Rainfall Events ◽  
Very High

Abstract Data collected during four heavy rainfall events that occurred in Ardèche (France) with the help of a 2D video disdrometer (2DVD) are used to investigate the structure of the raindrop distribution in both space and time. A first type of analysis is based on the reconstruction of 36-m-height vertical rainfall columns above the measuring device. This reconstruction is obtained with the help of a ballistic hypothesis applied to 1-ms time step series. The corresponding snapshots are analyzed with the help of universal multifractals. For comparison, a similar analysis is performed on the time series with 1-ms time steps, as well as on time series of accumulation maps of N consecutive recorded drops (therefore with variable time steps). It turns out that the drop distribution exhibits a good scaling behavior in the range 0.5–36 m during the heaviest portion of the events, confirming the lack of empirical evidence of the widely used homogenous assumption for drop distribution. For smaller scales, drop positions seem to be homogeneously distributed. The notion of multifractal singularity is well illustrated by the very high-resolution time series.

Heavy Rainfall Events over Central Oahu under Weak Wind Conditions during Seasonal Transitions

2020 ◽  
Vol 148 (10) ◽  
pp. 4117-4141
Author(s):  
Feng Hsiao ◽  
Yi-Leng Chen ◽  
David Eugene Hitzl
Keyword(s):  
Mixed Layer ◽  
Land Surface ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Subsequent Development ◽  
Precipitable Water ◽  
Trade Wind ◽  
Heavy Rainfall Event ◽  
Rainfall Events ◽  
Heavy Rainfall Events

AbstractShort-lived afternoon heavy rainfall events may form over central Oahu during seasonal transition periods (June and October) under favorable large-scale settings. These include a deep moist layer with relatively high precipitable water (>40 mm), blocking pattern in midlatitudes with a northeast–southwest moist tongue from low latitudes ahead of an upper-level trough, absence of a trade wind inversion, and weak (<3 m s−1) low-level winds. Our high-resolution (1.5 km) model results show that immediately before the storm initiation, daytime land surface heating deepens the mixed layer over central Oahu and the top of the mixed layer reaches the lifting condensation level. Meanwhile, the development of onshore/sea-breeze flows, driven by land–sea thermal contrast, brings in moist maritime air over the island interior. Finally, convergence of onshore flows over central Oahu provides the localized lifting required for the release of instability. Based on synoptic and observational analyses, nowcasting with a lead time of 2–3 h ahead of this type of event is possible. In the absence of orographic effects after removing model topography, processes that lead to heavy rainfall are largely unchanged, and subsequent development of heavy showers over central Oahu are still simulated. However, when surface heat and moisture fluxes are turned off, convective cells are not simulated in the area. These results indicate that daytime heating is crucial for the development of this type of heavy rainfall event under favorable large-scale settings.

scholarly journals A Comparison of Two Heavy Rainfall Events during the Terrain-Influenced Monsoon Rainfall Experiment (TiMREX) 2008

2014 ◽  
Vol 142 (7) ◽  
pp. 2436-2463 ◽  
Author(s):  
Chuan-Chi Tu ◽  
Yi-Leng Chen ◽  
Ching-Sen Chen ◽  
Pay-Liam Lin ◽  
Po-Hsiung Lin
Keyword(s):  
Rainy Season ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Sea Breeze ◽  
Heavy Precipitation ◽  
Early Summer ◽  
Cold Pool ◽  
Mountain Range ◽  
Rainfall Events ◽  
Heavy Rainfall Events

Abstract Two contrasting localized heavy rainfall events during Taiwan’s early summer rainy season with the daily rainfall maximum along the windward mountain range and coast were studied and compared using a combination of observations and numerical simulations. Both events occurred under favorable large-scale settings including the existence of a moisture tongue from the tropics. For the 31 May case, heavy rainfall occurred in the afternoon hours over the southwestern windward slopes after a shallow surface front passed central Taiwan. The orographic lifting of the prevailing warm, moist, west-southwesterly flow aloft, combined with a sea breeze–upslope flow at the surface provided the localized lifting needed for the development of heavy precipitation. On 16 June before sunrise, pronounced orographic blocking of the warm, moist, south-southwesterly flow occurred because of the presence of relatively cold air at low levels as a result of nocturnal and rain evaporative cooling. As a result, convective systems intensified as they moved toward the southwestern coast. During the daytime, the cold pool remained over southwestern Taiwan without the development of onshore/upslope flow. Furthermore, with a south-southwesterly flow aloft parallel to terrain contours, orographic lifting aloft was absent and preexisting rain cells offshore diminished after they moved inland. Over northern Taiwan on the lee side, a sea breeze/onshore flow developed in the afternoon hours, resulting in heavy thundershowers. These results demonstrate the importance of diurnal and local effects on determining the location and timing of the occurrences of localized heavy precipitation during the early summer rainy season over Taiwan.

scholarly journals Prediction of the August 2018 heavy rainfall events over Kerala with high‐resolution NWP models

2020 ◽  
Vol 27 (2) ◽  
Author(s):  
Raghavendra Ashrit ◽  
Kuldeep Sharma ◽  
Sushant Kumar ◽  
Anumeha Dube ◽  
S. Karunasagar ◽  
...  
Keyword(s):  
High Resolution ◽  
Heavy Rainfall ◽  
Rainfall Events ◽  
Heavy Rainfall Events
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