DSpace Collection:
http://hdl.handle.net/2122/276
2015-03-30T14:11:30ZThe IONORT-ISP-WC system: inclusion of an electron collision frequency model for the D-layer
http://hdl.handle.net/2122/9417
Title: The IONORT-ISP-WC system: inclusion of an electron collision frequency model for the D-layer
Authors: Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia
Abstract: The IONORT-ISP system (IONOspheric Ray-Tracing – IRI-SIRMUP-PROFILES) was recently developed and tested by comparing the measured oblique ionograms over the radio link between Rome (41.89ºN, 12.48ºE), Italy, and Chania (35.51ºN, 24.02ºE), Greece, with the IONORT-ISP simulated oblique ionograms (Settimi et al., 2013). The present paper describes an upgrade of the system to include: a) electron-neutral collision have been included by using a collision frequency model that consists of a double exponential profile; b) the ISP three dimensional (3-D) model of electron density profile grid has been extended down to the altitude of the D-layer; c) the resolution in latitude and longitude of the ISP 3-D model of electron density profile grid has been increased from 2°x2° to 1°x1°. Based on these updates, a new software tool called IONORT-ISP-WC (WC means with collisions) was developed, and a database of 33 IONORT-ISP-WC synthesized oblique ionograms calculated for single (1-hop paths) and multiple (3-hop paths) ionospheric reflections. The IONORT-ISP-WC simulated oblique ionograms were compared with the IONORT-IRI-WC synthesized oblique ionograms, generated by applying IONORT in conjunction with the International Reference Ionosphere (IRI) 3-D electron density grid, and the observed oblique ionograms over the aforementioned radio link. The results obtained show that (1) during daytime, for the lower ionospheric layers, the traces of the synthesized ionograms are cut away at low frequencies because of HF absorption; (2) during night-time, for the higher ionospheric layers, the traces of the simulated ionograms at low frequencies are not cut off (very little HF absorption); (3) the IONORT-ISP-WC MUF values are more accurate than the IONORT-IRI-WC MUF values.
Description: SPECIAL ISSUE: International Reference Ionosphere (IRI) and Global Navigation Satellite Systems (GNSS)2015-04-14T22:00:00ZThe Mt. Etna data mining software
http://hdl.handle.net/2122/9392
Title: The Mt. Etna data mining software
Authors: Aliotta, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Cannata, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Cassisi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; D'Agostino, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Di Grazia, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Ferrari, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Langer, H.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Messina, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Montalto, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Reitano, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Spampinato, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia
Editors: Puglisi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Spampinato, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Reitano, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Mangiagli, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia
Abstract: Mt. Etna is permanently active requiring a continuous data acquisition a multidisciplinary monitoring system
where huge data masses accumulate and pose severe difficulties of interpretation. Therefore the INGV staff
has developed a number of software tools for data mining, aiming at identifying structures in the data which
can be related to the volcanic activity and furnish criteria for the definition of alert systems. We tackle the
problem by applying methods of clustering and classification. We identify data groups by defining a measure
of similarity or distance. Data groups may assume various shapes, once forming convex clouds once
complex concave bodies. The tool “KKAanalysis” is a basket of clustering methods and forms the backbone
of the tremor-based automatic alarm system of INGV-OE. It exploits both SOM and Fuzzy Clustering.
Besides seismic data the concept has been applied to petrochemic data as well as in a combined analysis of
gas-emission data and seismic data. The software “DBSCAN” focuses on density-based clustering that
allows discovering clusters with arbitrary shape. Here, clusters are defined as dense regions of objects in the
data space separated by regions of low density. In DBSCAN a cluster grows guaranteeing that the density
within a group of objects exceeds some threshold. In the context of volcano monitoring the method is
particularly promising in the recognition of ash particles as they have a rather irregular shape. The “MOTIF”
software allows identifying typical wave forms in time series. It overcomes shortages of methods like cross-
correlation, which entail a high computational effort. MOTIF on the other hand can recognize non-similarity
of two patterns on a small number of data points without going through the whole length of the data vectors.
The development includes modules for feature extraction and post-processing verifying the validity of the
results obtained by the classifiers.2014-07-06T22:00:00ZCorrection’s method of the electron density model in ionosphere by ray tracing techniques
http://hdl.handle.net/2122/9340
Title: Correction’s method of the electron density model in ionosphere by ray tracing techniques
Authors: Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, S.; Università Sapienza, Dipartimento di Fisica, p.le Aldo Moro 2, I-00185 Rome, Italy; Baskaradas, J. A.; School of Electrical & Electronics Engineering, Shanmugha Arts, Science, Technology & Research Academy (SASTRA) University, Tirumalaisamudram, Thanjavur, 613 401 Tamilnadu, India
Abstract: When applying the ray tracing in ionospheric propagation, the electron density modelling is the main input of the algorithm, since phase refractive index strongly depends on it. Also the magnetic field and frequency collision modelling have their importance, the former as responsible for the azimuth angle deviation of the vertical plane containing the radio wave, the latter for the evaluation of the absorption of the wave. Anyway, the electron density distribution is strongly dominant when one wants to evaluate the group delay time characterizing the ionospheric propagation. From the group delay time, azimuth and elevation angles it is possible to determine the point of arrival of the radio wave when it reaches the Earth surface. Moreover, the procedure to establish the target (T) position is one of the essential steps in the Over The Horizon Radar (OTHR) techniques which require the correct knowledge of the electron density distribution. The group delay time generally gives rough information of the ground range, which depends on the exact path of the radio wave in the ionosphere. This paper focuses on the lead role that is played by the variation of the electron density grid into the ray tracing algorithm, which is correlated to the change of the electron content along the ionospheric ray path, for obtaining a ray tracing as much reliable as possible. In many cases of practical interest, the group delay time depends on the geometric length and the electron content of the ray path. The issue is faced theoretically, and a simple analytical relation, between the variation of the electron content along the path and the difference in time between the group delays, calculated and measured, both in the ionosphere and in the vacuum, is obtained and discussed. An example of how an oblique radio link can be improved by varying the electron density grid is also shown and discussed.2015-03-14T23:00:00ZAutomatic interpretation of oblique ionograms
http://hdl.handle.net/2122/9339
Title: Automatic interpretation of oblique ionograms
Authors: Ippolito, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Francis, M.; IPS Radio & Space Services, Bureau of Meteorology, Level 15, Tower C, 300 Elizabeth Street, Sydney, Australia; Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cesaroni, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia
Abstract: We present an algorithm for the identification of trace characteristics of oblique ionograms allowing determination of the Maximum Usable Frequency (MUF) for communication between the transmitter and receiver. The algorithm automatically detects and rejects poor quality ionograms. We performed an exploratory test of the algorithm using data from a campaign of oblique soundings between Rome, Italy (41.90 N, 12.48 E) and Chania, Greece (35.51 N, 24.01 E) and also between Kalkarindji, Australia (17.43 S, 130.81 E) and Culgoora, Australia (30.30 S, 149.55 E). The success of these tests demonstrates the applicability of the method to ionograms recorded by different ionosondes in various helio and geophysical conditions.2015-03-14T23:00:00ZA first look at the Gargano (southern Italy) seismicity as seen by the local scale OTRIONS seismic network
http://hdl.handle.net/2122/9186
Title: A first look at the Gargano (southern Italy) seismicity as seen by the local scale OTRIONS seismic network
Authors: De Lorenzo, S.; Università di Bari "Aldo Moro", Dipartimento di Scienze della Terra e Geoambientali, Bari; Romeo, A.; Università di Bari "Aldo Moro", Dipartimento di Scienze della Terra e Geoambientali, Bari; Falco, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Michele, M.; Università di Bari "Aldo Moro", Dipartimento di Scienze della Terra e Geoambientali, Bari; Tallarico, A.; Università di Bari "Aldo Moro", Dipartimento di Scienze della Terra e Geoambientali, Bari
Abstract: OnApril 2013,alocal scale seismic network,namedOTRIONS, composed of twelve short period (1 Hz) three component seismometers, has been located in the northern part of the Apulia (Southern Italy). At each station, the acquisition systemallows the recording of data in situ and their real time transfer toa
seismic laboratory located at the Dipartimento di Scienze della Terra e Geoambientali of Università di Bari "Aldo Moro". The preliminary real time detection and localization of the events is automatically realized by using the SeisComp3 software. In the first two months of data acquisition, the network
recorded about one hundred low magnitude (ML<2) earthquakes. In that follows,wepresent the results of a study aimed at investigating the crustal structure of the Gargano promontory. To this aimweanalyzed the seismic events recorded in the area by the “Istituto Nazionale di Geofisica e Vulcanologia”
(INGV) in the period 2006-2012 and the seismic events recorded by the OTRIONS network in the first two months of acquisition (march and april 2013). From the inversion of P and S travel times of INGV events we inferred a preliminary 3-layer Vp velocity model. The Moho is located at a depth of 27-30 km, in
agreement with previous studies. A linearized inversion scheme that uses Velest (Kissling et al., 1994), allowed us to infer a 1D velocity model from the joint inversion of INGV and OTRIONS datasets of P and S travel times. On the whole, the number of earthquakes recorded by the OTRIONS seismic network is
higher than 1200 in the period april,2013-march,2014.2014-08-23T22:00:00ZRay theory formulation and ray tracing method. Application in ionospheric propagation
http://hdl.handle.net/2122/9139
Title: Ray theory formulation and ray tracing method. Application in ionospheric propagation
Authors: Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, S.; Dipartimento di Fisica, Università “Sapienza”, p.le Aldo Moro 2, 00185 Roma, Italia
Abstract: This work will lead to ray theory and ray tracing formulation. To deal with this problem the theory of classical geometrical optics is presented, and applications to ionospheric propagation will be described. This provides useful theoretical basis for scientists involved in research on radio propagation in inhomogeneous anisotropic media, especially in a magneto-plasma. Application in high frequencies (HF) radio propagation, radio communication, over-the-horizon-radar (OTHR) coordinate registration and related homing techniques for direction finding of HF wave, all rely on ray tracing computational algorithm. In this theory the formulation of the canonical, or Hamiltonian, equations related to the ray, which allow calculating the wave direction of propagation in a continuous, inhomogeneous and anisotropic medium with minor gradient, will be dealt. At least six Hamilton’s equations will be written both in Cartesian and spherical coordinates in the simplest way. These will be achieved by introducing the refractive surface index equations and the ray surface equations in an appropriate free-dimensional space. By the combination of these equations even the Fermat’s principle will be derived to give more generality to the formulation of ray theory. It will be shown that the canonical equations are dependent on a constant quantity H and the Cartesian coordinates and components of wave vector along the ray path. These quantities respectively indicated as ri(τ), pi(τ) are dependent on the parameter τ, that must increase monotonically along the path. Effectively, the procedure described above is the ray tracing formulation. In ray tracing computational techniques, the most convenient Hamiltonian describing the medium can be adopted, and the simplest way to choose properly H will be discussed. Finally, a system of equations, which can be numerically solved, is generated.2014-10-22T22:00:00ZThe calculation of ionospheric absorption with modern computers
http://hdl.handle.net/2122/9104
Title: The calculation of ionospheric absorption with modern computers
Authors: Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia
Abstract: New outcomes are proposed for ionospheric absorption starting from the Appleton-Hartree formula, in its complete form. The range of applicability is discussed for the approximate formulae, which are usually employed in the calculation of non-deviative absorption coefficient. These results were achieved by performing a more refined approximation that is valid under quasi-longitudinal (QL) propagation conditions. The more refined QL approximation and the usually employed non-deviative absorption are compared with that derived from a complete formulation. Their expressions, nothing complicated, can usefully be implemented in a software program running on modern computers. Moreover, the importance of considering Booker’s rule is highlighted. A radio link of ground range D = 1000 km was also simulated using ray tracing for a sample daytime ionosphere. Finally, some estimations of the integrated absorption for the radio link considered are provided for different frequencies.2014-10-14T22:00:00ZScientific review on the ionospheric absorption and research prospects of a Complex Eikonal model for one-layer ionosphere
http://hdl.handle.net/2122/9071
Title: Scientific review on the ionospheric absorption and research prospects of a Complex Eikonal model for one-layer ionosphere
Authors: Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Ippolito, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cesaroni, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia
Abstract: Thepresent paper conducts a scientific review on ionospheric absorption, extrapolating the research prospects of a complex eikonal
model for one-layer ionosphere. As regards the scientific review, here a quasi-longitudinal (QL) approximation for nondeviative
absorption is deduced which is more refined than the corresponding equation reported by Davies (1990). As regards the research
prospects, a complex eikonal model for one-layer ionosphere is analyzed in depth here, already discussed by Settimi et al. (2013). A
simple formula is deduced for a simplified problem. A flat, layered ionospheric medium is considered, without any horizontal
gradient. The authors prove that the QL nondeviative amplitude absorption according to the complex eikonal model is more
accurate than Rawer’s theory (1976) in the range of middle critical frequencies.2014-08-05T22:00:00ZLa nuova infrastruttura di acquisizione e distribuzione dati della Rete Integrata Nazionale GPS (RING)
http://hdl.handle.net/2122/8972
Title: La nuova infrastruttura di acquisizione e distribuzione dati della Rete Integrata Nazionale GPS (RING)
Authors: Falco, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Cecere, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; D'Ambrosio, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia2014-03-24T23:00:00ZGPSView: monitoraggio in tempo reale delle stazioni GPS acquisite tramite Nanometrics Libra VSAT
http://hdl.handle.net/2122/8971
Title: GPSView: monitoraggio in tempo reale delle stazioni GPS acquisite tramite Nanometrics Libra VSAT
Authors: Falco, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia2014-03-19T23:00:00Z