Precipitation In Italy Research Articles

RIVERBED, BANKS AND BEYOND: AN EXAMINATION OF ROMAN INFRASTRUCTURE AND INTERVENTIONS IN RESPONSE TO HYDROLOGICAL RISK IN THE PO–VENETIAN PLAIN

Water poses a particular challenge to the cities and settlements of the Po–Venetian plain. The region has some of the highest levels of precipitation in Italy and is criss-crossed by dozens of rivers, including the Po, Adige and Tagliamento. Throughout history, there was considerable hydrological risk to the well-being of riparian communities from hazards such as flooding and lateral channel movement, yet local residents did not sit idly by. This article synthesizes the available evidence for Roman responses to hydrological risk in the Po–Venetian plain from the first century BC to the sixth century AD, examining their workings and the hazards they sought to counteract, integrating them into wider discussions on risk in the Roman world. The responses are divided into the categories of defensive works (embankments and dykes) and channel interventions (channel rectification, channel diversion and dredging). While the effectiveness of these methods is questioned, in particular their potential to cause unintended changes to the watercourse, the decision by riparian communities to undertake them suggests a degree of local success. Nevertheless, an examination of the archaeological and palaeoclimatic evidence suggests a discrepancy between peak intervention and peak risk, implying increasing vulnerability and risk acceptance amongst riparian communities during late antiquity.

Modelling and forecasting temperature and precipitation in Italy

We study the monthly average temperature in Italy for the period 1991-2015. The increase or decrease of the average temperature with respect to the previous year is modelled as a discrete-time Markov chain having four possible states. Similarly, a Markov chain is proposed as a model for the variations of the monthly amount of precipitation. Based on these models, it is possible to forecast whether the temperature and the amount of precipitation are likely to vary significantly in the long term.

Peer review report 1 on “Mapping oxygen stable isotopes of precipitation in Italy”

Peer review report 1 on “Mapping oxygen stable isotopes of precipitation in Italy”

Mapping oxygen stable isotopes of precipitation in Italy

Abstract Study region Italy. Study focus The oxygen isotope composition from 266 pluviometers was used to study the spatial variability of δ 18 O and its relationship with Italian orography. The local meteoric water lines (LMWLs) of northern, southern and central Italy and Sicily are reformulated and a new definition of isotopic variations with elevation is provided. New hydrological insights for the region Altitude and, to a lesser extent, latitude are the main geographical factors affecting the isotopic signature of precipitation in Italy. A high-resolution map of the spatial distribution of 18 O content in precipitation was created using the identified relationship between δ 18 O/Latitude-Altitude and the spatial distribution of the residuals. The general features of the δ 18 O distribution map may be summarised as follows: δ 18 O distribution over the Alps clearly depends on latitude and altitude, whereas over the Apennines, which run down the whole peninsula from north-west to south-east, it is more affected by altitude, the contour lines roughly following the axis of the chain. The isotope compositions on the western side of the peninsula are generally higher than those of the east at the same elevation and latitude; they are more or less uniform in the northern plain of Italy.

Paleoclimate of the Southern Adriatic Sea region during the ‘Medieval Climate Anomaly’ reflected by organic walled dinoflagellate cysts

To obtain insight into the character and forcing of southern Italian climate change during the ‘Medieval Climate Anomaly’ ( c. ad 900–1200), marine sediments deposited between ad 990 and 1200 from the Gulf of Taranto have been analyzed for their dinoflagellate cyst content with a 3.5 yr resolution. The reconstructed sea surface temperature (SST) appears to be lower than today. We observe a clear 11.4 yr cyclicity in the reconstructed SST series. Furthermore, there is a good matching between SST and global 14C anomalies. This suggests that solar activity might have had an important influence on the local climate during Medieval time. Short-term fluctuations in accumulation rates of aerobic degradation resistant species that react sensitively on the trophic state of the upper waters and/or are characteristic for river plume waters indicate that the trophic state of the upper waters is closely linked to river discharge, which in turn is strongly related to precipitation in Italy. We reconstruct low river discharge/precipitations in the Adriatic area synchronous to widespread drought events in other nearby subtropical regions. We attribute this to NAO and ENSO related large-scale ocean–atmosphere circulation shifts during the Medieval period. Furthermore, we suggest that eruptions of southern Italian volcanoes might have influenced the local upper water nutrient conditions as well.

Short term climate variability during “Roman Classical Period” in the eastern Mediterranean

To obtain insight into character and potential forcing of short-term climatic and oceanographic variability in the southern Italian region during the “Roman Classical Period” (60 BC–AD 200), climatic and environmental reconstructions based on a dinoflagelate cyst record from a well dated site in the Gulf of Taranto located at the distal end of the Po-river discharge plume have been established with high temporal resolution. Short-term fluctuations in accumulation rates of the Adriatic Surface Water species Lingulodinium machaerophorum, the freshwater algae Concentricystes and species resistant to aerobic degradation indicate that fluctuations in the trophic state of the upper waters are related to river discharge of northern and eastern Italian rivers which in turn are strongly related to precipitation in Italy. The dinoflagellate cyst association indicates that local sea surface temperatures which in this region are strongly linked to local air temperatures were slightly higher than today. We reconstruct that sea surface temperatures have been relatively high and stable between 60 BC–AD 90 and show a decreasing trend after AD 90. Fluctuations in temperature and river discharge rates have a strong cyclic character with main cyclicities of 7–8 and 11 years. We argue that these cycles are related to variations of the North Atlantic Oscillation climate mode. A strong correlation is observed with global variation in Δ 14C anomalies suggesting that solar variability might be one of the major forcings of the regional climate. Apart from cyclic climate variability we observed a good correlation between non-cyclic temperature drops and global volcanic activity indicating that the latter forms an additional major forcing factor of the southern Italian climate during the Roman Classical Period.

Stable isotope ratios in meteoric recharge and groundwater at Mt. Vulture volcano, southern Italy

Summary A rain gauge network consisting of five sites located at different altitudes, ranging from 320 to 1285 m.a.s.l., was installed at Mt. Vulture volcano (southern Italy). Rain water samples were collected monthly over a two-year period and their isotopic composition (δ18O and δD) was analyzed. During the same period, circulating groundwater was sampled from 24 springs and wells distributed throughout the study area. Monthly isotopic composition values were used to determine the local meteoric water line (LMWL). Its slope is slightly lower than the relationship defined by Longinelli and Selmo (Longinelli, A., Selmo, E., 2003. Isotopic composition of precipitation in Italy: a first overall map. J. Hydrol. 270, 75–88) for southern Italy. The groundwater samples analyzed were distributed essentially along the LMWL. The weighted local meteoric water line (WLMWL), defined through the mean values weighted by the rainfall amount, however, may define in a short range the meteoric end-member in the local hydrological cycle more precisely. Since most of the groundwater sampling locations do not show seasonal variations in their stable isotope values, the flow system appears to be relatively homogeneous. The mean altitude of the recharge by rainfall infiltration was estimated on the basis of the local vertical isotopic gradient δ18O. A few springs, which show anomalous isotopic values, reveal more regional circulation systems, associated with tectonic structures responsible for the ascent of deeper water.

Isotopic composition of precipitation in Northern Italy: Reverse effect of anomalous climatic events

Summary A few years ago the first comprehensive map of the isotopic composition of precipitation in Italy was published, based on the results obtained over several years at 77 different locations in Italy. The lack of financial support made it impossible to continue this study extended to the whole country. However, the collection of composite monthly samples continued at 12 locations in Northern Italy. The main purpose was to check the variability through time of the yearly mean isotopic values calculated for some of these stations according to previous data and to add a couple of stations in the western section of Alps, along the Italy–France border for which we had no data. We report here the data obtained for the years 2002–2004. This period is particularly interesting since, during 2003, most of Europe, and particularly Italy, experienced the hottest summer of the last century. In principle, this climatic event should have determined a marked enrichment in heavy isotopes in the annual weighted means for that year. On the contrary, all but one of the collection sites yielded yearly mean isotopic values that were considerably more negative than the mean values calculated for the previous years. This is essentially due to the marked decrease in the yearly amount of precipitation and particularly in that of spring and summer so that the mean weighted yearly isotopic values are heavily affected by the amount of precipitation and the isotopic values of the winter and autumn months. This shift was particularly marked at the collection sites located along the northern slope of the Apennines where a marked “shadow” effect related to westerly air masses moving over the Apennines exists. An important aspect of these data concerns the interpretation of isotopic values of palaeoprecipitation: in the case of palaeo-isotopic changes determined by environmental conditions similar to those reported here, a “normal” interpretation of the data may be misleading.

Isotopic composition of precipitation in Italy: a first overall map

Composite monthly samples of atmospheric precipitation were collected over different periods of time ranging from one to seven years at 77 different locations throughout Italy. These samples were measured for their oxygen and hydrogen isotopic composition to obtain basic information for hydrological and meteorological studies in this area. On the basis of the results obtained a first map of the isotopic composition of precipitations in Italy has been drawn up. The main features of this map are the following: (1) no isotopic latitudinal gradient has been found along the Tyrrhenian coast from Sicily to the Italian–French border, despite the considerable range of latitude; (2) a minor latitudinal gradient is found in the southeasternmost section of the country (Apulia), partially favored by the local morphology; (3) a marked ‘shadow effect’ of the Apennines is apparent along the southern section of the Po valley and along the central section of the Adriatic coast; (4) the contribution of water vapor from the northernmost section of the Adriatic sea affects the eastern and central sections of the Po plain; (5) the shadow effect of the Alps is considerably smaller than expected; (6) the isotopic vertical gradients calculated in nine different areas and based on groups of two to five different stations vary but are essentially close to about −0.2‰/100 m; (7) when mean monthly temperature values were available, their relationship with the isotopic composition of precipitation was found to be, on average, very poor; (8) the relationship between mean δ 18O and mean δD calculated for the collection locations shows shifts of both the slope and the deuterium excess when compared to the global meteoric water line. These shifts are different for northern, central, and southern Italy; (9) in a few cases anomalously low monthly δ values suggest the existence of pronounced ‘amount effects’.

Atmospheric circulation and precipitation in Italy for the last 50 years

AbstractDaily precipitation series from 75 Italian stations, for the period 1951–95, are clustered into six regions and the average is calculated for each area. For each average series, the seasonal and annual total precipitation and the number of wet days are calculated. The relationship between precipitation and atmospheric circulation is examined using correlation analysis. Atmospheric circulation is represented by five indexes: the well known North Atlantic oscillation index, a blocking frequency index, a Mediterranean oscillation index based on the 500 hPa geopotential record for Algiers, a Western European zonal circulation index (WEZCI) constructed from Madrid + Barcelona and Trondheim + Lund surface pressure records, and a new Mediterranean circulation index (MCI) constructed from Marseille and Jerusalem surface pressure records. All the indexes are calculated using monthly series; then seasonal and yearly averages are obtained. The indexes that show the most interesting correlation with total precipitation and number of wet days are WEZCI and MCI. Trend analysis of the index series gives evidence of a signal connected to a strong increase in winter air pressure in the Mediterranean area starting around 1980. Copyright © 2002 Royal Meteorological Society.