1,720,997 research outputs found
VARIABILITY OF THE AIR TEMPERATURE AND PRECIPITATION FROM 1884 TO 1960 IN THE HISTORICAL TIME SERIES OF MONTEVERGINE (AVELLINO) - PRELIMINARY RESULTS
No full textRISULTATI PRELIMINARI DELL’ANALISI DI UNA NUOVA SERIE DI DATI CLIMATICI NELL’ITALIA MERIDIONALE (OSSERVATORIO DI MONTEVERGINE, AV)
No full textDetection of heat and cold waves in Montevergine time series (1884-2015)
Full text linkIn recent years, extreme events related to cooling and heating have taken high resonance, motivating the scientific community to carry out an intensive research activity, aimed to detect their variability and frequency. In this work, we have investigated about the frequency, the duration, the severity and the intensity of heat and cold waves in a Southern Italy high-altitude region, by analysing the climatological time series collected in Montevergine observatory. Following the guidelines provided by CLIVAR project (Climate and Ocean Variability, Predictability and Change), we have adopted indicators based on percentiles and duration to define a heat wave and cold event. Main results have highlighted a strong and significant positive trend in the last 40 years (1974-2015) in heat waves frequency, severity and intensity. On the contrary, in recent decades, cold wave events have exhibited a significant and positive trend only in intensity. Moreover, through the usage of two Wavelet Analysis tools, the Cross Wavelet Transform and the Wavelet Coherence, we have investigated about the connections between the extreme temperature events occurred in Montevergine and the large-scale atmospheric patterns. The heat wave events have exhibited relevant relationships with the Western European Zonal Circulation and the North Atlantic Oscillation, whereas the variability of cold wave events have shown linkages with the Eastern Mediterranean Pattern and the North Sea Caspian Pattern. In addition, the main features of synoptic patterns that have caused summer heat waves and winter cold waves in Montevergine site are presented
TIME SERIES ANALYSES OF CLIMATOLOGICAL RECORDS FROM A HIGH ALTITUDE OBSERVATORY IN SOUTHERN ITALY (MONTEVERGINE, AV)
No full textIn this work we show the results obtained from the homogenization and the analysis of a climatic time series (mean temperature and total precipitation) collected in the Southern Italy Apennines (Montevergine, AV). This climatological time series is one of the oldest of Apennines mountains and it’s very meaningful for the high altitude region climate study, being located at 1280 m asl (40° 56°N, 14° 43’E). The homogenization of time series is performed using the Standard Normal Homogeneity Test and its non-parametric version. Precipitation time series is characterized only by a discontinuity, occurred on 1950, while temperature time series is affected by multiple inhomogeneities, caused by changing in instruments location, human errors and instruments accuracy degradation. The analysis of homogenized time series is carried out through Wavelet Analysis, in order to investigate about series behavior in time-frequency spectrum, and LOWESS smoothing, aiming to highlight the decadal variability; moreover, we use a linear polynomial model to define trends. The results highlight an increase in annual mean temperature of 0.5°C/100 years and a decrease in annual total precipitation of 32%/100 years (-667 mm/100 years). Positive temperature trend is evident on all seasons, except on autumn, while negative precipitation tendency is particularly sharp on spring. The signals are characterized by a strong oscillation between 1940 and 1950 on 2-4 years period. The opposite trends that characterize temperature and precipitation are very steep from mid-1970s up to early 2000s; in this period the two parameters are strongly anti-correlated, unlike previous decades, in which they show an unstable coupling. Mediterranean Circulation Index (MCI) captures a large portion of precipitation variability, while thermal regime is strongly related to Eastern Mediterranean Pattern (EMP)
Historical snowfall precipitation data in the Apennine Mountains, Italy
No full textThis database includes a large collection of quality-controlled and homogenized historical snow records measured in the 1951-2001 period in the Central and Southern Apennine Mountains (Italy). Such data have been manually digitized from the Hydrological Yearbooks of the Italian National Hydrological and Mareographic Service (hereafter, NHMS), the institution that managed the hydro-meteorological data collection in Italy from 1917 to 2002. More specifically, the rescued dataset includes the monthly observations of three different variables:
· The snow cover duration (SCD), which is defined as total number of days in a given month with snow depth on the ground >=1 cm. This variable is available for 110 stations between 288 and 1430 m above the sea level (ASL).
· The number of days with snowfall (NDS), which is total number of days in a given month on which the accumulated snowfall (i.e. the amount of fresh snow with respect to the previous observations) is at least 1 cm. This variable is available for 114 stations between 288 and 1430 m ASL.
· The height of new snow (HN), which is defined as the monthly amount of fresh snow (expressed in cm). The monthly value is intended as the sum of daily HN data observed in a determined month. This variable is available for 120 stations between 288 and 1750 m ASL.
Note that for HN variable, the data availability is restricted to the period 1971-2001.
The considered dataset has been subjected to an accurate quality control consisting of several statistical tests: the gross error test, which flags the data that are above or below acceptable physical limits, the consistency test, which involves an inter-variable check, and the tolerance test, which is focused on the outlier detection. In addition, the homogeneity of the rescued time series has been checked using Climatol method (Guijarro, 2018). The latter is based on the Standard Normal Homogeneity Test (Alexandersson, 1986) for the identification of the breaks and on a linear regression approach for the adjustments (Easterling and Peterson, 1995). Climatol has been also employed for the filling of missing values.
The database is structured into three different folders (one for each variable). In a determined folder, the user finds two files, one containing the main information regarding the available stations (code, station name, latitude and longitude (in decimal degrees) and altitude ASL (in m)), the other one the monthly time series for the considered variable.
Note that the original data sources of this database, the Hydrological Yearbooks of the NHMS, are freely accessible in printed version (i.e. as scanned images in portable document format) through the Italian Institute for Environmental Protection and Research (ISPRA) website (http://www.bio.isprambiente.it/annalipdf).
Additional information about the data rescue processing can be found in the preprint “Historical snowfall measurements in the Central and Southern Apennine Mountains: climatology, variability and trend”, open for discussion in The Cryosphere journal (https://doi.org/10.5194/egusphere-2024-1056)
X-BAND WEATHER RADAR MONITORING OF PRECIPITATION FIELDS IN NAPLES URBAN AREAS: DATA QUALITY, COMPARISON AND ANALYSIS
No full textRain gauges are considered a traditional method for measuring rainfall. They are simpler than weather radar in terms of management, but they can only provide point measurements and offer limited information on spatial rainfall variability (e.g., Borga and Tonelli, 2002; Steiner et al., 2009). To capture the spatial variability of storms over relatively large areas, weather radars are needed (Battan, 1973; Doviak and Zrnic, 1993). Usually, the costs of installation and maintenance these systems are one of the main limitations for their diffusion. Recently, the increased use of X band frequencies for weather radar applications, for instance to cover small catchments and urban areas, has pushed the activity to develop, improve and study such systems (e.g., Delrieu et al., 1999b; Maki et al., 2005; Marzano et al., 2010; Picciotti et al., 2013).
In this respect, since November 2011, a single polarization X-band weather radar, called WR-10X, has been installed in Naples’ urban area at the top of Castel Sant’Elmo (280 m a.s.l.). The radar belongs to the Campania Center for Marine and Atmospheric Modelling and Monitoring (CCMMMA) of the University of Naples “Parthenope” and provides high resolution rainfall data which are necessary for monitoring urban flash flood and for runoff simulation in urban drainage.
The objective of this work is to calibrate WR-10X rain-rate estimation with the available rain-gauge network using time-space correlation approach in according to rainfall nature (stratiform, convective and mixed). To mitigate ground and sea clutter returns, path attenuation and other impairments, a processing chain has been applied to radar data before rain-rate estimation. To pursue this aim, a large set of data covering a two years period and consisting of radar scans and gauge measurements, have been collected and carefully processed. The structure of the article will follow the list of the topics just mentioned
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Comparison between 3D-Var and 4D-Var data assimilation methods for the simulation of a heavy rainfall case in central Italy
No full textAbstract. This work aims to provide a comparison between three dimensional and four dimensional variational data assimilation methods (3D-Var and 4D-Var) for a heavy rainfall case in central Italy. To evaluate the impact of the assimilation of reflectivity and radial velocity acquired from Monte Midia Doppler radar into the Weather Research Forecasting (WRF) model, the quantitative precipitation forecast (QPF) is used.The two methods are compared for a heavy rainfall event that occurred in central Italy on 14 September 2012 during the first Special Observation Period (SOP1) of the HyMeX (HYdrological cycle in Mediterranean EXperiment) campaign. This event, characterized by a deep low pressure system over the Tyrrhenian Sea, produced flash floods over the Marche and Abruzzo regions, where rainfall maxima reached more than 150 mm 24 h−1.To identify the best QPF, nine experiments are performed using 3D-Var and 4D-Var data assimilation techniques. All simulations are compared in terms of rainfall forecast and precipitation measured by the gauges through three statistical indicators: probability of detection (POD), critical success index (CSI) and false alarm ratio (FAR). The assimilation of conventional observations with 4D-Var method improves the QPF compared to 3D-Var. In addition, the use of radar measurements in 4D-Var simulations enhances the performances of statistical scores for higher rainfall thresholds.
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Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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