Search

Due to its particular position in the middle of the Mediterranean Sea and its complex andsteep orography, the Calabrian peninsula (southern Italy) is frequently affected by severeprecipitation events and is particularly prone to significant ground effects. In the earlyafternoon of August 20, 2018, a storm cell caused a flash flood that affected the smallRaganello Creek, in the northern side of the region, causing 10 casualties at the outlet of theRaganello Gorges, where the extension of the catchment is about 100 km2. Though theregional monitoring network is rather dense, in the surroundings of the disaster site raingauges were not able to measure the very intense and highly localized rainfall. However, thethree-hour Surface Rainfall Total (SRT) provided by a single polarization Doppler radar ofthe Italian National Radar Network showed a storm cell with rain peaks of theorder of 70-100 mm/hour in a small mountain area not covered by the monitoringnetwork. The objective of this work is to evaluate the ability of the state-of-the-artmeteorological/hydrological modelling in simulating the Raganello Creek event using bothone-way and fully-coupled approaches, by means of the WRF/WRF-Hydro modellingsystem. The Advanced Research WRF (ARW) Model, version 3.9.1 is used with two one-waynested domains at the resolution of 10 km and 2 km respectively, while the resolution ofthe hydrological model, based on WRF-Hydro version 5.0, is 200 m. The initialand boundary conditions are provided by the ECMWF’s Integrated ForecastingSystem (IFS), in its deterministic forecast version at 9 km resolution. Several WRFsimulations have been carried out, before choosing the best configuration, to testthe impact of the initial conditions, horizontal resolutions and parameterizationschemes. Results show that the model, particularly in its fully-coupled version, is able to predictreasonably well the occurrence of the event both in terms of rainfall, thus identifying thestorm cell, and in terms of hydrological impact, reproducing timely what mighthave been (unfortunately, observed runoff is not available) the event hydrograph. [ABSTRACT FROM AUTHOR]

Recent large-scale estimations of CO2 fluxes suggest that water bodies play an important role in carbon dioxide emissions; however, these estimates fail to consider the heterogeneities of degassing rates and the actual extent of water-air interfaces. The reasons can be found in the difficulty of mapping the smaller headwater streams and the heterogeneities of the physical and biochemical processes that control CO2 generation and transfer. Here we developed and built a small floating respiration chamber using an Arduino board connected to a low-power CO2, temperature and relative humidity sensor and a barometric pressure sensor; the chamber is specifically designed to properly create a sealed air volume above the very shallow and narrow headwater streams, where water velocities are high and the riverbed is very bumpy. This chamber allows the simultaneous measurement of CO2 concentration in both atmosphere and water via the headspace method, along with degasification rates that can be estimated from the dynamics of CO2 concentration in the chamber volume. We tested this new sensor system in a small alpine catchment in northern Italy, showing that it might represent a valid -and cheap- alternative to the state-of-the-art techniques that involve the use of tracer gases and very expensive pCO2 sensors. [ABSTRACT FROM AUTHOR]

The Arda and Stirone marine successions (Italy) represent key-sections for the lower Pleistocene, as they deposited continuously within a frame of climate change, recording the Calabrian cooling as testified by the occurrence of the "northern guests" Arctica islandica, Hyalinea balthica and Neogloboquadrina pachyderma left-coiled. Despite its historical importance in the past, when the first occurrence of A. islandica in the Mediterranean Sea was used as the main criterion to mark the former Pliocene-Pleistocene boundary, the age of this bioevent was never well constrained. Here, we describe the Stirone depositional environment and constrain for the first time the section age using calcareous nannofossils and foraminifera biostratigraphy; we correlate the Arda and Stirone sections, complementing biostratigraphic and magnetostratigraphic data. Our results indicate that A. islandica first occurred in both the successions slightly below the top of the CNPL7 biozone (dated at 1.71 Ma). The comparison with other lower Pleistocene Mediterranean marine successions indicates that the stratigraphically lowest level where A. islandica first occurred in the Mediterranean Sea is in the Arda and Stirone sections; these environments satisfied the ecological requirements for the establishment and the proliferation of the species, which only subsequently colonized southern Italy and other areas of the Mediterranean Sea. [ABSTRACT FROM AUTHOR]