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Sgrigna, V.
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Sgrigna, V.
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- PublicationOpen AccessArtificial and natural electromagnetic signals revealed during two years in the Amare cave (Central Italy)(1994-11)
; ; ; ; ; ; ; ; ;Bella, F.; Dipartimento di Fisica, Università “La Sapienza”, Roma, Italy ;Bella, R.; IBM - SEMEA, Roma, Italy ;Biagi, P. F.; Dipartimento di Scienze della Terra, Università “La Sapienza”, Roma, Italy ;Caputo, M.; Dipartimento di Fisica, Università “La Sapienza”, Roma, Italy ;Della Monica, G.; Dipartimento di Fisica, Università “La Sapienza”, Roma, Italy ;Ermini, A.; Dipartimento di Fisica, Università “La Sapienza”, Roma, Italy ;Plastino, W.; Dipartimento di Fisica, Università “La Sapienza”, Roma, Italy ;Sgrigna, V.; Dipartimento di Fisica, Università “La Sapienza”, Roma, Italy; ; ; ; ; ; ; n 1990, some instrumentation was set up in the Amare cave (southern slope of the Gran Sasso chain, L'Aquila) in order to pick up electric signals ranging from 0.3 to 300 kHz, magnetic signals from 0.3 to 30 kHz and seismoacoustic signals by means of three geophones with natural frequencies of 0.3 kHz, 25 kHz and 150 kHz. Data are recorded every ten minutes on a solid state memory. The analysis of the data allows us to establish the existence of electromagnetic fields of distant origin connected with broadcastings and with tropical lightning activity and the discontinuous presence of local electric and magnetic signals, coupled with seismoacoustic ones, connected with weather events. A qualitative explanation of these near fields is given.188 325 - PublicationRestrictedA statistical analysis on the relationship between thunderstorms and the sporadic E Layer over Rome(2013-11-09)
; ; ; ; ; ; ;Barta, V.; University of West Hungary, Kitaibel P´al Doctoral School of Environmental Science, Bajcsy-Zsilinszky str. 4., H-9400 Sopron, Hungary; Research Centre for Astronomy and Earth Sciences, GGI, Hungarian Academy of Sciences, Csatkai str. 6-8., H-9400, Sopron, Hungary ;Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Sgrigna, V.; Roma Tre University, Faculty ofMathematics, Physics and Natural Sciences, Dipartimento di Fisica “Edoardo Amaldi”, Via della Vasca Navale, 84, 00146, Rome, Italy ;Conti, L.; Universit`a Telematica Internazionale UNINETTUNO, Facolt`a di Ingegneria, Corso Vittorio Emanuele II, 39, 00186 Rome, Italy ;Satori, G.; Research Centre for Astronomy and Earth Sciences, GGI, Hungarian Academy of Sciences, Csatkai str. 6-8., H-9400, Sopron, Hungary; ; ; ; ; Meteorological processes (cold fronts, mesoscale convective complexes, thunderstorms) in the troposphere can generate upward propagating waves in the neutral atmosphere affecting the behaviour of the ionosphere. One type of these waves are the internal atmospheric gravity waves (AGWs) which are often generated by thunderstorms. Davis & Johnson (2005) found in low pressure systems that a localized intensification of the sporadic E layer (Es) can be attributed to lightnings. To confirm this result, we have performed two different statistical analysis using the time series of the critical frequency (foEs), the virtual height of the sporadic E layer (h’Es), and meteorological observations (lightnings, Infrared maps) over the ionospheric station of Rome (41.9◦ N, 12.5◦ E). In the first statistical analysis, we separated the days of 2009 into two groups: stormy days and fair-weather days, then we studied the occurrence and the properties of the Es separately for the two different groups. No significant differences have been found. In the second case, a superposed epoch analysis (SEA) was used to study the behaviour of the critical frequency and virtual height 100 hours before and after the lightnings. The SEA shows a statistically significant decrease in the critical frequency after the time of the lightnings, which indicates a sudden decrease in the electron density of the sporadic E layer associated with lightnings.314 27 - PublicationOpen AccessNormal and anomalous behaviour of electric, magnetic and seismoacoustic signals recorded in the Amare cave(1996-01)
; ; ; ; ; ; ; ;Bella, F.; Dipartimento di Fisica, III Università di Roma, Italy ;Biagi, P. F.; Dipartimento di Fisica, Università di Bari, Italy ;Caputo, M.; Dipartimento di Fisica, Università La Sapienza, Roma, Italy ;Della Monica, G.; Dipartimento di Fisica, III Università di Roma, Italy ;Ermini, A.; Dipartimento di Scienze e Tecnologie Fisiche ed Energetiche, Università «Tor Vergata», Roma, Italy ;Plastino, W.; Dipartimento di Fisica, III Università di Roma, Italy ;Sgrigna, V.; Dipartimento di Scienze e Tecnologie Fisiche ed Energetiche, Università «Tor Vergata», Roma, Italy; ; ; ; ; ; Since 1987 multichannel instrumentation has been recording electromagnetic and seismoacoustic emissions in the Amare cave (Gran Sasso í L'Aquila). Equipment detecting RMC (Principality of Monaco) longwave broadcasting (216 kHz) has been operating in the same place. Data collected during this period have pointed out two different phenomena called «quiet» and «perturbed» that characterize the normal behaviour of the cave. On 25 August 1992 an earthquake with M = 3.9 occurred in the Gran Sasso area and on 4 June 1993 an earthquake with M = 4.3 occurred in Umbria, 100 km to north of the Amare cave. Before these earthquakes, electromagnetic, seismoacoustic, and RMC data showed anomalies. Here we present the observed phenomenology and discuss the possibility that the anomalies can be considered precursors of the earthquakes.166 195 - PublicationRestrictedGNSS data filtering optimization for ionospheric observation(2015)
; ; ; ; ; ; ;; ; ;; In the last years, the use of GNSS (Global Navigation Satellite Systems) data has been gradually increasing, for both scientific studies and technological applications. High-rate GNSS data, able to generate and output 50-Hz phase and amplitude samples, are commonly used to study electron density irregularities within the ionosphere. Ionospheric irregularities may cause scintillations, which are rapid and random fluctuations of the phase and the amplitude of the received GNSS signals. For scintillation analysis, usually, GNSS signals observed at an elevation angle lower than an arbitrary threshold (usually 15 , 20 or 30 ) are filtered out, to remove the possible error sources due to the local environment where the receiver is deployed. Indeed, the signal scattered by the environment surrounding the receiver could mimic ionospheric scintillation, because buildings, trees, etc. might create diffusion, diffraction and reflection. Although widely adopted, the elevation angle threshold has some downsides, as it may under or overestimate the actual impact of multipath due to local environment. Certainly, an incorrect selection of the field of view spanned by the GNSS antenna may lead to the misidentification of scintillation events at low elevation angles. With the aim to tackle the non-ionospheric effects induced by multipath at ground, in this paper we introduce a filtering technique, termed SOLIDIFY (Standalone OutLiers IDentIfication Filtering analYsis technique), aiming at excluding the multipath sources of non-ionospheric origin to improve the quality of the information obtained by the GNSS signal in a given site. SOLIDIFY is a statistical filtering technique based on the signal quality parameters measured by scintillation receivers. The technique is applied and optimized on the data acquired by a scintillation receiver located at the Istituto Nazionale di Geofisica e Vulcanologia, in Rome. The results of the exercise show that, in the considered case of a noisy site under quiet ionospheric conditions, the SOLIDIFY optimization maximizes the quality, instead of the quantity, of the data.158 8