196,634 research outputs found
I cabrei dell’ordine ospitaliero: dalla documentazione alla ricerca di persistenze e trasformazioni del paesaggio rurale del versante meridionale dei Berici
No full textI cabrei figurati e descrittivi, individuati dalla ricerca d’archivio di M.G. Bulla Borga, offrono interessanti considerazioni, oltre che sulle trasformazioni del paesaggio rurale, anche sulla prassi di conservazione dei patrimoni religiosi e sulle professionalità dei mappatori
Multi-model convection-resolving simulations of the October 2018 Vaia storm over Northeastern Italy
No full textThe aim of this study is to identify the main mesoscale features and mechanisms responsible for the generation of a very intense precipitation and wind storm event, named “Vaia”, that affected the eastern Italian Alps on 27–29 October 2018. The event was characterized by extreme accumulated precipitation (up to 850 mm in three days) and exceptionally strong winds, causing severe and widespread impacts, such as floods, landslides, and extensive damages to forests and growing stock. The synoptic situation was characterized by a trough, which deepened over the eastern Atlantic, extending to France and Spain, driving a strong moist flow towards the Alpine region. At the surface, a wide cyclonic area developed over the western Mediterranean, east of the trough axis, and moved, deepening, towards northwestern Italy. The storm is investigated using a comprehensive dataset composed of both observations and numerical simulations by means of two models, namely WRF and MOLOCH, at convection-permitting resolution. The analysis highlights that the storm was characterized by two consecutive phases with strong precipitations, both fed by an intense moist southerly flow. In particular, the second phase was also marked by strong wind gusts in the Alpine area, exceeding 50 m s−1 at some weather stations. It is found that these extreme wind gusts were connected to the presence of an intense southerly low-level jet immediately ahead of a cold front, displaying an average wind speed of 35 m s−1 at 1500 m MSL. The comparison between observations and numerical results shows that the main characteristics of the storm are well simulated by both models, confirming the high predictability of this kind of events, typically associated with well-defined large-scale forcing. Also local scale features are reasonably captured by the simulations, despite the high complexity of the Alpine orography. However, WRF significantly underestimates total precipitation amounts over the most affected areas, while wind speed is overestimated by both models in the inner Alpine sectors
"Un raffronto fra il teorema di incompletezza di Goedel e il teorema di Tarski sulla nozione di verità"
No full text
Differential orographic impact on sub-hourly, hourly, and daily extreme precipitation
No full textExtreme precipitation of multiple durations is responsible for major natural hazards in mountainous regions, such as flash floods and debris flows. Understanding the orographic impact on the statistics of precipitation extremes is therefore crucial for improving hydrological design and risk management strategies. Here, we use a novel statistical approach for the analysis of extremes based on ordinary events to improve our understanding of the orographic impact on extreme precipitation of durations ranging between 5 min and 24 h. We focus on Trentino, a rough orographic region in the eastern Italia Alps, and use data from 78 quality-controlled rain gauges with 5-minute resolution. We show that our framework well reproduces the statistical properties of the observed annual maxima (Nash-Sutcliffe 0.82–0.95, Bias from -4% to 7%) as well as their relation with orography. We then exploit the reduced uncertainty of this approach to quantify the orographic impact on precipitation right-tail statistics and on extreme return levels using a regression analysis. We identify two main modes of orographic relationship: a reverse orographic effect for hourly and sub-hourly durations (10–20% decrease per 1000 m elevation) and an orographic enhancement for durations of ∼8 h or longer (7.5–10% increase per 1000 m elevation). We observe that these two modes result from three main precipitation regimes, which show different proportion between extreme and very-extreme events and which emerge at very short durations (∼20 min or shorter), mid durations (∼30 min-1 hour) and long durations (∼2 h or longer). These findings are of interest for risk management applications and climate change impact studies
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