148 research outputs found
Biometric characterization of the Red-legged Partridges Alectoris rufa of northwestern Italy
The biometrics of the Red-legged Partridge Alectoris rufa has been relatively well studied in the western part of its distribution range (Iberian Peninsula and France), especially due to the available large hunting bag samples. Conversely, the Italian population is poorly characterized. We analysed a sample of 254 live birds trapped and ringed in the northern Apennines (province of Alessandria, northwestern Italy), by measuring body mass and the length of wing, eighth primary, tail, tarsus and bill. We found significant differences in some biometric measurements between sex and age classes. A subsample of birds (n = 112) was genetically tested for introgressive hybridization with A. chukar, an introduced species, showing that 16.1 % of free-living partridge are hybrid individuals. When we analysed separately "pure"and "introgressed"birds we found only small biometric differences in body mass of adult males. Finally, our results were compared with the biometry of other populations from the whole natural range of the species (France, Spain and Portugal) showing a negative biometric trend of wing length from westernmost to southeastern birds of the range. Introgressed birds found in the studied population were not easily distinguishable with biometric criteria from pure A. rufa rufa, so genetic analysis is highly recommended when planning reintroductions or restocking
Surface deformation of active volcanic areas retrieved with the SBAS-DInSAR technique: an overview
This paper presents a comprehensive overview of the surface deformation retrieval capability of the Differential
Synthetic Aperture Radar Interferometry (DInSAR) algorithm, referred to as Small BAseline Subset (SBAS)
technique, in the context of active volcanic areas. In particular, after a brief description of the algorithm some
experiments relevant to three selected case-study areas are presented. First, we concentrate on the application of
the SBAS algorithm to a single-orbit scenario, thus considering a set of SAR data composed by images acquired
on descending orbits by the European Remote Sensing (ERS) radar sensors and relevant to the Long Valley
caldera (eastern California) area. Subsequently, we address the capability of the SBAS technique in a multipleorbit
context by referring to Mt. Etna volcano (southern Italy) test site, with respect to which two different ERS
data set, composed by images acquired both on ascending and descending orbits, are available. Finally, we take
advantage of the capability of the algorithm to work in a multi-platform scenario by jointly exploiting two different
sets of SAR images collected by the ERS and the Environment Satellite (ENVISAT) radar sensors in the
Campi Flegrei caldera (southern Italy) area. The presented results demonstrate the effectiveness of the algorithm
to investigate the deformation field in active volcanic areas and the potential of the DInSAR methodologies within
routine surveillance scenario
A QUANTITATIVE ASSESSMENT OF DInSAR TIME SERIES ACCURACY IN VOLCANIC AREAS: FROM THE FIRST TO SECOND GENERATION SAR SENSORS
We perform a quantitative assessment of the accuracy of Differential SAR Interferometry (DInSAR) time series in volcanic areas, retrieved through “first” and “second generation” SAR data. In particular, we analyze the impact that the wavelengths and looking geometries may have in the DInSAR measurement retrieval depending on the radar
system. To this aim, we focus on the DInSAR algorithm referred to as Small BAseline Subset (SBAS) to generate mean deformation velocity maps and corresponding time series starting from sequences of SAR images. Moreover, we consider collections of SAR data acquired by the ERS-1/2 and ENVISAT (C-band), and COSMO-SkyMed (Xband) sensors over the volcanic area of the Campi Flegrei caldera, Southern Italy. We invert these SAR data sequences through the SBAS-DInSAR technique, thus obtaining C- and X- band deformation time series that we compare to continuous GPS measurements, the latter assumed as reference. The achieved results provide, in addition to a clear picture of the surface deformation phenomena already occurred and occurring in the selected case study, relevant indications for the analysis of the SBAS-DInSAR time series accuracies in volcanic areas passing from the first to second generation SAR sensors.PublishedMĂĽnich1IT. Reti di monitoraggio e Osservazionirestricte
The 2004–2006 uplift episode at Campi Flegrei caldera (Italy): Constraints from SBAS-DInSAR ENVISAT data and Bayesian source inference
We investigate the 2004–2006 uplift phase of Campi
Flegrei caldera (Italy) by exploiting the archive of ascending
and descending ENVISAT SAR data acquired from
November 2002 to November 2006. The SBAS-DInSAR
technique is applied to generate displacement mean velocity
maps and time series. An appropriate post-processing step is
subsequently applied to map the areas whose temporal
deformation behavior is correlated with that of the
maximum uplift zone. Our results show that the
deformation also extends outside the volcanological limits
of the Neapolitan Yellow Tuff caldera, without significant
discontinuities. The DInSAR data are inverted by
considering a finite spheroid and an isotropic pointsource.
The inversion results suggest that the new uplift is
characterized by a source location similar to the previous
small uplift event of 2000 and to the long term subsidence
of the 1990’s. In particular, the source is located at a depth
of about 3.2 km and very close to the city of Pozzuoli (about
800 m offshore, to the SW); the associated volume variation
is about 1.1 106 m3/year.PublishedL073081.10. TTC - TelerilevamentoJCR Journalreserve
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