المؤلفون: Franceschina, Gianlorenzo, Tento, Alberto

المساهمون: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Milano, Milano, Italia, Retired, CNR - Istituto per la Dinamica dei Processi Ambientali, Milano, Italia

مصطلحات موضوعية: Earthquake ground motions, Seismic attenuation, Site effects, Wave propagation, Wave scattering and diffraction, 04.06. Seismology

الوصف: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved. ; Estimation of local seismic response plays a key role in assessing local seismic hazard and particularly in the design of shaking scenarios. Modelling local seismic response involves knowing of the shear wave velocity (Vs) and quality factor (Qs) profiles for the site in question. The many techniques that have been developed to assess Vs in surface deposits produce reliable measurements of Vs , but these rarely correspond to direct measurements of Qs . The latter is often considered through damping measures from laboratory tests on small-scale soil samples, which can provide information primarily on intrinsic attenuation, neglecting the contribution of scattering effects. In this paper, using seismic recordings obtained at the surface and in boreholes at 100 m depth, we estimate an average value of Qs of some characteristic alluvial deposits of the Po Plain (northern Italy). Data come from a microseismic network which sampled an almost uniform lithology in the central Po Plain and consisted of three surface and four borehole stations with an interstation distance of about 2 km. The average value of Qs of the shallowest 100 m of the sedimentary strata, Qs100, is estimated by considering: (1) the high-frequency attenuation of seismic waves due to propagation through the corresponding stratigraphy and (2) the interference between incident and surface-reflected waves observed at borehole stations. We parametrize the first through k0_100, the difference between the values of the spectral decay parameter kappa (k) estimated at the surface and at the boreholes depth, respectively. We use the second in order to compute Vs100, the time-averaged Vs referred to the uppermost 100 m stratigraphy. We obtain: k0_100 = (11 ± 3) ms, ...

العلاقة: Geophysical Journal International; /234 (2023); http://hdl.handle.net/2122/16919Test

الإتاحة: https://doi.org/10.1093/gji/ggad185Test
http://hdl.handle.net/2122/16919Test

المؤلفون: Sharma Dhakal, Apsara, Molinari, Irene, Boschi, Lapo

المساهمون: Dipartimento di Geoscienze, Universitá degli Studi di, 35131 Padova, Italy, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Bologna, Bologna, Italia

مصطلحات موضوعية: Earthquake source observations, Surface waves and free oscillations, Theoretical seismology, Wave propagation, 04.06. Seismology, 05.01. Computational geophysics

الوصف: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved. ; Different approaches to map seismic rupture in space and time often lead to incoherent results for the same event. Building on earlier work by our team, we ‘time-reverse’ and ‘backpropagate’ seismic surface wave recordings to study the focusing of the time-reversed field at the seismic source. Currently used source-imaging methods relying on seismic recordings neglect the information carried by surface waves, and mostly focus on the P-wave arrival alone. Our new method combines seismic time reversal approach with a surface wave ray-tracing algorithm based on a generalized spherical-harmonic parametrization of surface wave phase velocity, accounting for azimuthal anisotropy. It is applied to surface wave signal filtered within narrow-frequency bands, so that the inherently 3-D problem of simulating surface wave propagation is separated into a suite of 2-D problems, each of relatively limited computational cost. We validate our method through a number of synthetic tests, then apply it to the great 2004 Sumatra–Andaman earthquake, characterized by the extremely large extent of the ruptured fault. Many studies have estimated its rupture characteristics from seismological data (e.g. Lomax, Ni et al., Guilbert et al., Ishii et al., Krüger & Ohrnberger, Jaffe et al.) and geodetic data (e.g. Banerjee et al., Catherine et al., Vigny et al., Hashimoto et al., Bletery et al.). Applying our technique to recordings from only 89 stations of the Global Seismographic Network (GSN) and bandpass filtering the corresponding surface wave signal around 80-to-120, 50-to-110 and 40-to-90 s, we reproduce the findings of earlier studies, including in particular the northward direction of rupture propagation, its approximate spatial extent ...

العلاقة: Geophysical Journal International; 2/233 (2023); http://hdl.handle.net/2122/16213Test

الإتاحة: https://doi.org/10.1093/gji/ggac493Test
http://hdl.handle.net/2122/16213Test

المؤلفون: Settimi, Alessandro

المساهمون: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Roma2, Roma, Italia

مصطلحات موضوعية: Appleton-Hartree’s formula, Booker’s rule, ″Strong″ and ″weak″ Quasi-Longitudinal (QL) conditions, Walker’s approximation, Ionospheric HF ray-tracing, oblique and vertical sounding, and absorption, 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous, 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics, 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation, 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous, 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation

الوصف: For the phase refraction index of high frequency (HF) waves in the ionospheric medium exists a well-established theory. However, under the Quasi-Longitudinal (QL) conditions, scientific literature presents various formulas that are not equivalent and that, in some cases, give rise to wrong results. In the present study, further consequences of Booker's rule are discussed, illustrating the validity ranges of the above-mentioned approximate formulas; and the different regimes for applying such QL formulas are described, along with the consequences in simulating the ionospheric HF ray-tracing, oblique and vertical sounding, and absorption. ; Published ; PA003 ; 2A. Fisica dell'alta atmosfera ; 7SR AMBIENTE – Servizi e ricerca per la società ; 3IT. Calcolo scientifico ; 7TM.Sviluppo e Trasferimento Tecnologico ; JCR Journal

العلاقة: Annals of Geophysics; 1/65 (2022); Azzarone, A., C. Bianchi, M. Pezzopane, M. Pietrella, C. Scotto and A. Settimi (2012). IONORT: a Windows software tool to calculate the HF ray tracing in the ionosphere, Comput. Geosci. - UK, 42, 57-63, doi:10.1016/j.cageo.2012.02.008. Barry Research Corporation (1975). VOS-1A User Manual, Palo Alto, California, USA. Barry Research Corporation (1989). RCS-5B Chirpsounder Receiver Operating and Service Manual, Palo Alto, California, USA. Bianchi, C. (1990). Note sulle interazioni delle onde elettromagnetiche con il plasma ionosferico, Istituto Nazionale di Geofisica, U. O. Aeronomia, Rome, Italy, 149 pp. [in Italian]. Bilitza, D. and B. W. Reinisch (2008). International reference ionosphere 2007: improvements and new parameters, Adv. Space Res., 42 (4), 599–609, doi:10.1016/j.asr.2007.07.048. Booker, H. G. (1935). The application of the magnetoionic theory to the ionosphere, Proc. R. Soc. Lond. A, 150 (870), 267–286, doi:10.1098/rspa.1935.0101. Budden, K. G. (1988). The Propagation of Radio Waves: The Theory of Radio Waves of Low Power in the Ionosphere and Magnetosphere, Cambridge University Press, Cambridge, UK, pp. 688. Chapman, S. (1931a). The absorption and dissociative or ionizing effect of monochromatic radiation in an atmosphere on a rotating earth, Proc. Phys. Soc., 43 (1), 26-45, doi:10.1088/0959-5309/43/1/305. Chapman, S. (1931b). The absorption and dissociative or ionizing effect of monochromatic radiation in an atmosphere on a rotating earth – Part II, Grazing incidence, Proc. Phys. Soc., 43 (5), 483-501, doi:10.1088/0959-5309/43/5/302. Davies, K. (1990). Ionospheric Radio, Peter Peregrinus Ltd. (ed.) on behalf of the Institution of Electrical Engineers (IET), London, UK, 508 pp. Davies, K. and G. A. M. King (1961). On the validity of some approximations to the Appleton-Hartree formula, Journal of Research of the National Bureau of Standards – Section D: Radio Propagation, Vol. 65D, No. 4, 323-332, doi:10.6028/jres.065D.042. Haselgrove, J. (1955). Ray theory and a new method of ray tracing, Conference on the Physics of the Ionosphere, Proc. Phys. Soc. London, 23, 355-364. Haselgrove, C. B. and J. Haselgrove (1960). Twisted ray paths in the ionosphere, Proc. Phys. Soc. London, 75 (3), 357-363, doi:10.1088/0370-1328/75/3/304. International Geomagnetic Reference Field (IGRF-12). IAGA Division V-MOD Geomagnetic Field Modelling, 2012 (http://www.ngdc.noaa.gov/IAGA/vmod/igrf.htmlTest). International Reference Ionosphere (IRI)-2007. Virtual Ionosphere, Thermosphere, Mesosphere Observatory (VITMO), 2012 (http://ccmc.gsfc.nasa.gov/modelweb/models/iri_vitmo.phpTest). Jones, R. M. and J. J. Stephenson (1975). A versatile three-dimensional ray tracing computer program for radio waves in the ionosphere, OT Report, 75-76, U. S. Department of Commerce, Office of Telecommunication, U. S. Government Printing Office, Washington, USA, 185 pp. Kelso, J. M. (1964). Radio ray propagation in the ionosphere, McGraw-Hill electronic sciences series, McGraw Hill Book Company, Inc., New York, 408 pages. Lu, B. W. (1996). A Unified Theory of Ionospheric Propagation of Short Radio Waves with Special Emphasis on Long-Distance Propagation, Progress In Electromagnetics Research (PIER), 13, 87–114, http://www.jpier.org/pier/pier.php?paper=940810Test. McNamara, L. F. (1991). The Ionosphere: Communications, Surveillance, and Direction Finding (Orbit: A Foundation Series). Published by Krieger Pub Co, Hardcover, 248 pp. Nickisch, L. J. (2008). Practical Applications of Haselgrove’s Equations for HF systems, Radio Sci. Bulletin, 325, 36-48 (http://www.ursi.org/files/RSBissues/RSB_325_2008_06.pdfTest). Pezzopane, M., M. Pietrella, A. Pignatelli, B. Zolesi, and L. R. Cander (2011). Assimilation of autoscaled data and regional and local ionospheric models as input sources for real-time 3-D International Reference Ionosphere modelling, Radio Sci., 46 (5), RS5009, doi:10.1029/2011RS004697. Pezzopane, M., M. Pietrella, A. Pignatelli, B. Zolesi, and L. R. Cander (2013). Testing the three-dimensional IRI-SIRMUP-P mapping of the ionosphere for disturbed periods, Adv. Space Res., 52 (10), 1726-1736, doi:10.1016/j.asr.2012.11.028. Ratcliffe, J. A. (1959). The Magneto-Ionic Theory and its Applications to the Ionosphere, Cambridge University Press, Cambridge, 206 pp., 1959. Rydbeck, O. E. H. (1940). On the propagation of electro-magnetic waves in a ionized medium and the calculation of the heights of the ionoized layers of the atmosphere, Phil. Mag. Series 7, 30 (201), 282-293, doi:10.1080/14786444008520718. Scotto, C. and A. Settimi (2014). The calculation of ionospheric absorption with modern computers, Adv. Space. Res., 54 (8), 1642-1650, doi:10.1016/j.asr.2014.06.017. Settimi, A., A. Ippolito, C. Cesaroni and C. Scotto (2014a). Scientific review on the ionospheric absorption and research perspectives of a Complex Eikonal model for one-layer Ionosphere, Int. J. Geophys., Volume 2014, Article ID 657434, 14 pages, doi:10.1155/2014/657434. Settimi, A., M. Pezzopane, M. Pietrella, C. Bianchi, C. Scotto, E. Zuccheretti E. and J. Makris (2013a). Testing the IONORT-ISP system: a comparison between synthesized and measured oblique ionograms, Radio Sci., 48 (2), 167-179, doi:10.1002/rds.20018. Settimi, A., M. Pietrella, M. Pezzopane and C. Bianchi (2015). The IONORT-ISP-WC system: inclusion of an electron collision frequency model for the D-layer, In Special Issue: International Reference Ionosphere (IRI) and Global Navigation Satellite Systems (GNSS), Adv. Space Res., 55 (8), 2114-2123, doi 10.1016/j.asr.2014.07.040. Settimi, A., M. Pietrella, M. Pezzopane, B. Zolesi, C. Bianchi and C. Scotto (2014b). The COMPLEIK subroutine of the IONORT-ISP system for calculating the non-deviative absorption: A comparison with the ICEPAC formula, Adv. Space. Res., 53 (2), 201-218, doi:10.1016/j.asr.2013.10.035. Settimi, A., U. Sciacca and C. Bianchi (2013b). Scientific review on the Complex Eikonal, and research perspectives on the Ionospheric Ray-tracing and Absorption, Quaderni di Geofisica, 112, 29 pp. Stewart, F. G. (undated). Ionospheric Communications Enhanced Profile Analysis & Circuit (ICEPAC) Prediction Program, Technical Manual, 91 pp. (http://elbert.its.bldrdoc.gov/hf_prop/manuals/icepac_tech_manual.pdfTest). Taylor, M. (1933). The Appleton-Hartree formula and dispersion curves for the propagation of electromagnetic waves through an ionized medium in the presence of an external magnetic field, part 1: curves for zero absorption, Proc. Phys. Soc., 45 (2), 245-265 doi:10.1088/0959-5309/45/2/310. Taylor, M. (1934). The Appleton-Hartree formula and dispersion curves for the propagation of electromagnetic waves through an ionized medium in the presence of an external magnetic field, part 2: curves with collisional friction, Proc. Phys. Soc., 46 (3), 408-419, doi:10.1088/0959-5309/46/3/313. Titheridge, J. E. (1959). Ray paths in the ionosphere - Approximate calculations in the presence of the earth's magnetic field, J. Atm. Terr. Phys., 14 (1-2), 50-62, doi:10.1016/0021-9169(59)90055-8. Walker, A. D. M. (1961). The Quasi-Longitudinal Approximation to the Appleton-Hartree Equation, Nature, 189 (4766), 742, doi:10.1038/189742a0, 1961. Westfold, K. C. (1951). The interpretation of the magneto-ionic theory, J. Atm. Terr. Phys., 1 (3), 152-186, doi:10.1016/0021-9169(51)90018-9. Zuccheretti, E., G. Tutone, U. Sciacca, C. Bianchi, and B. J. Arokiasamy (2003). The new AIS-INGV digital ionosonde, Ann. Geophys. – Italy, 46(4), 647–659, doi:10.4401/ag-4377.; http://hdl.handle.net/2122/15529Test

الإتاحة: https://doi.org/10.4401/ag-8728Test
https://doi.org/10.1016/j.cageo.2012.02.008Test
http://hdl.handle.net/2122/15529Test

المؤلفون: Kästle, Emanuel, Molinari, Irene, Boschi, Lapo, Kissling, Edi, AlpArray Working Group

المساهمون: Institute for Geological Sciences, Freie Universität Berlin, Germany, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Bologna, Bologna, Italia, Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy, Dipartimento di Geoscienze, Universitá degli Studi di Padova, Italy, Institut des Sciences de la Terre Paris, Sorbonne Université, CNRS-INSU, ISTeP UMR 7193, F-75005 Paris, France, Department of Earth Sciences, ETH Zürich, Switzerland, www.alparray.ethz.ch

مصطلحات موضوعية: Seismic anisotropy, Seismic interferometry, Seismic tomography, Wave propagation, Continental tectonics: compressional, 04.01. Earth Interior, 04.06. Seismology

الوصف: This article has been accepted for publication in Geophysical Journal International ©: The Authors 2021. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Uploaded in accordance with the publisher's self-archiving policy. ; Ambient-noise records from the AlpArray network are used to measure Rayleigh wave phase velocities between more than 150,000 station pairs. From these, azimuthally anisotropic phase-velocity maps are obtained by applying the Eikonal tomography method. Several synthetic tests are shown to study the bias in the Ψ2 anisotropy. There are two main groups of bias, the first one caused by interference between refracted/reflected waves and the appearance of secondary wavefronts that affect the phase travel-time measurements. This bias can be reduced if the amplitude field can be estimated correctly. Another source of error is related to the incomplete reconstruction of the travel-time field that is only sparsely sampled due to the receiver locations. Both types of bias scale with the magnitude of the velocity heterogeneities. Most affected by the spurious Ψ2 anisotropy are areas inside and at the border of low-velocity zones. In the isotropic velocity distribution, most of the bias cancels out if the azimuthal coverage is good. Despite the lack of resolution in many parts of the surveyed area, we identify a number of anisotropic structures that are robust: in the central Alps, we find a layered anisotropic structure, arc-parallel at midcrustal depths and arc-perpendicular in the lower crust. In contrast, in the eastern Alps, the pattern is more consistently E-W oriented which we relate to the eastward extrusion. The northern Alpine forleand exhibits a preferential anisotropic orientation that is similar to SKS observations in the lowermost crust and uppermost mantle. ; German Science Foundation (SPP-2017, Project Ha 2403/21-1); Swiss National Science Foundation SINERGIA Project CRSII2-154434/1 (Swiss-AlpArray); Progetto Pianeta Dinamico, ...

العلاقة: Geophysical Journal International; 1/229 (2022); http://hdl.handle.net/2122/15034Test

الإتاحة: https://doi.org/10.1093/gji/ggab453Test
http://hdl.handle.net/2122/15034Test

المؤلفون: Famiani, Daniela, Cultrera, Giovanna, Mercuri, Alessia, Michele, Maddalena, Vassallo, Maurizio

المساهمون: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Roma1, Roma, Italia, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione ONT, Roma, Italia, PENG, ZHIGANG

مصطلحات موضوعية: Microzonation, Seismology, Wave propagation, 04.06. Seismology

الوصف: This work focuses on the observation of data recorded by the seismic temporary network installed in the Amatrice area, under the umbrella of the Italian Center for Seismic Microzonation (http://www.centromicrozonazionesismica.itTest), following the M 6.0 earthquake of August 24, 2016 in Central Italy. The aim was studying the presence of an evident late low frequency wave packet observed in some of the recorded aftershocks. In order to interpret this phenomenon, we combined a beam-forming analysis performed on these data with the statistics on residuals of localizations related to the same events, recorded by the Italian Seismic Network (RSN). The total number of analyzed events, characterized by M≥=3 and epicentral distances between 30 and 55 Km, is 356. By observing the seismic traces of these events there was an evidence, in some of them, of a low frequency packet appearing 10 seconds after the first arrival. The evidence of this packet was correlated with epicentral distance and focal depth. For a subset of stations, considered as an array, a beam-forming analysis was performed by using the ObsPy toolbox (M. Beyreuther et al., 2010). Results of this analysis gave information in terms of slowness and azimuth to distinguish the main seismic phases of the considered events. In addition, by using locations of the RSN records (Chiaraluce et al., 2017), we performed a parallel analysis within the subset of events with clear evidence of the low frequency packet. We relocated these events by using the NonLinLoc code, with a fixed 1D P-wave velocity model, and varying the Vp/ Vs ratio in the range 1.6–2.0. We found that the P phases residuals are not influenced by the Vp/Vs ratio changes whereas the higher the Vp/Vs the lower are the S phases residuals. Higher values of Vp/Vs ratio, fixing Vp values, could mean a decrease of Vs connected to particular effects during the seismic waves path, that are probably due to geological heterogeneities at local or larger scale ; Published ; Miami, Florida ; 5T. Sismologia, geofisica ...

العلاقة: 2018 Seismology of the Americas Meeting; http://hdl.handle.net/2122/13717Test

الإتاحة: https://doi.org/10.1785/0220180082Test
http://hdl.handle.net/2122/13717Test

المؤلفون: Famiani, Daniela, Bordoni, Paola, Cara, Fabrizio, Cultrera, Giovanna, Mercuri, Alessia, Milana, Giuliano, Vassallo, Maurizio

المساهمون: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Roma1, Roma, Italia

مصطلحات موضوعية: Microzonation, Seismology, Wave propagation, Seismic amplification, 04.06. Seismology

الوصف: Following the M 6.0 of August 24 2016 Amatrice earthquake, a temporary seismic network was installed in the village of Amatrice, under the umbrella of the Italian Center for Seismic Microzonation (http://www.centromicrozonazionesismica.itTest), who conducted a preparatory survey to seismic microzonation with other Italian Institutions. This work focuses on data analysis of 7 stations installed in the Amatrice terrace which is representative of the geological condition of the town, with the aim of studying the possible presence of secondary effects during the seismic sequence caused by site conditions. Stiff bedrock outcroppings were also sampled with 2 reference stations. Preliminary analyses carried out on several earthquakes with Ml > 4 highlight the presence of a low frequency phase with a high energy content at 6 -7 seconds after the first P-wave arrival in almost all the recordings. This wave package was observed for the Mw 6.5 of October 30 earthquake and it has the highest amplitude of the entire recordings, having PGA values of 0.5 g and frequency between 2 and 3 Hz. Frequency-wavenumber analysis performed for the 7 stations array gives an important contribution for the interpretation of this phenomenon, showing that the low frequency wave-package for the examined events does not always show back-azimuth and slowness values compatible with the very first portion of the seismic record. It could be associated to the presence of reflected or refracted waves generated by secondary effects as geological or morphological heterogeneities at local or larger scale. ; Published ; Vienna ; 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

العلاقة: EGU General Assembly 2017; http://hdl.handle.net/2122/13718Test

الإتاحة: http://hdl.handle.net/2122/13718Test

المؤلفون: Latečki, Helena, Molinari, Irene, Stipçević, Josip

المساهمون: Department of Geophysics, Faculty of Science, University of Zagreb, Zagreb, Croatia, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Bologna, Bologna, Italia

مصطلحات موضوعية: Numerical simulation, 3D ground motion, Earthquake, Central Croatia, Zagreb, Seismic wave propagation, 3D crustal model, 04.06. Seismology

الوصف: In this work, we assess ground shaking in the wider Zagreb area by computing simulated seismograms at regional distances. For the purposes of the simulations, we assemble the 3D velocity and density model and test its performance. First, we compare the low-frequency simulations obtained using deterministic method for both new 3D model and a simple 1D model. We then continue the performance test by computing the full broadband seismo- grams. To do that, we apply the hybrid technique in which the low frequency (f<1 Hz) and high frequency (f=1–10 Hz) seismograms are obtained separately using deterministic and stochastic method, respectively, and then reconciled into a single time series. We apply this method to the MW=5.3 event and four smaller (3.0

العلاقة: Bulletin of Earthquake Engineering; /20 (2022); http://hdl.handle.net/2122/14835Test

الإتاحة: https://doi.org/10.1007/s10518-021-01227-5Test
http://hdl.handle.net/2122/14835Test

المؤلفون: Settimi, A., Bianchi, C., Scotto, C., Azzarone, A., Lozito, A.

المساهمون: Settimi, A., Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Bianchi, C., Scotto, C., Azzarone, A., Lozito, A., Santucci, Sandro, Dipartimento di Fisica, Università dell’’Aquila.

مصطلحات موضوعية: Ray tracing algorithm, Radio wave propagation, Ionospheric models, 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation

الوصف: It is well known that a 3D ray tracing algorithm furnishes the ray’s coordinates, the three components of the wave vector and the calculated group time delay of the wave along the path. The latter quantity can be compared with the measured group time delay to check the performance of the algorithm. Simulating a perfect reflector at an altitude equal to the virtual height of reflection, the virtual time delay is assumed as a real time delay. For a monotonic electronic density profile we find a very small relative difference between the calculated and the virtual delay for both analytic and numerical 3D electronic density models. ; REGIONE ABRUZZO, PROVINCIA DELL'AQUILA, COMUNE DELL'AQUILA, UNIVERSITA' DEGLI STUDI DELL'AQUILA, DIPARTIMENTO DI FISICA (UNIVERSITA' DELL'AQUILA), EPS, ENEA, ISTITUTO NAZIONALE DI FISICA NUCLEARE (INFN), CNISM, CNR, ISTITUTO NAZIONALE DI GEOFISICA E VULCANOLOGIA, DMD, SPRINGER, EPL, EPJ B, McGRAW HILL, CAEN, LECROY, AMETEK, ASSING, BCC ROMA, CRISEL INSTRUMENTS, CANTINA TOLLO, WOLFRAM MATHEMATICA ADALTA DISTRIBUTORE UFFICIALE PER L'ITALIA, MICRON FOUNDATION, VACUUM SCIENCE, FLAMAR, REALE MUTUA ASSICURAZIONI AGENZIA DELL'AQUILA, ORTEC, PI, PERKIN ELMER, 2M STRUMENTI, LASER OPTRONIC, TAYLOR&FRANCIS GROUP, HAMAMATSU, FONDAZIONE CASSA DI RISPARMIO DELLA PROVINCIA DELL'AQUILA. ; Submitted ; L’Aquila, Italia ; 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale ; open

العلاقة: XCVII Congresso Nazionale SIF (Società Italiana di Fisica); Bianchi, C., Settimi, A., Azzarone, A., IONORT - Ionosphere Ray-Tracing (Programma di ray-tracing nel magnetoplasma ionosferico), INGV Technical Report N. 161, INGV Printing Office, Rome, Italy, 2010. Bilitza, D., International Reference Ionosphere IRI-90 (ed.), National Space Science Data Center (NSSDC) Report 90-22, Greenbelt, Maryland, 1990. Budden, K. G., The propagation of the radio wave, Cambridge University Press, Cambridge, 1985. Davies, K., Ionospheric Radio, Peter Peregrinus Ltd. (ed.), London, UK, 1990. Jones, R. M., Stephenson, J. J., A versatile three-dimensional ray tracing computer program for radio waves in the ionosphere, OT Report, 75-76, U. S. Department of Commerce, Office of Telecommunication, U. S. Government Printing Office, Washington, U. S., 1974. Scotto C., Electron density profile calculation technique for Autoscala ionogram analysis, Adv. Space Res., 44 (6), 756–766, 2009.; http://hdl.handle.net/2122/7130Test

الإتاحة: http://hdl.handle.net/2122/7130Test

المؤلفون: Tardelli, A., Fagundes, P. R., Pezzopane, M., Pillat, V. G., Venkatesh, K.

المساهمون: Tardelli, A., Universidade do Vale do Paraíba (UNIVAP), São José dos Campos, Brazil, Fagundes, P. R., Pezzopane, M., Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Pillat, V. G., Venkatesh, K., #PLACEHOLDER_PARENT_METADATA_VALUE#

مصطلحات موضوعية: Ionogram, F layer, F3 layer, F4 layer, low-latitude ionosphere, 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous, 01. Atmosphere::01.02. Ionosphere::01.02.02. Dynamics, 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics, 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation, 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques

الوصف: The study of multiple stratification of the F layer has the initial records in the midtwentieth century. Since then, many studies were focused on F3 layer. The diurnal, seasonal, and solar activity variations of the F3 layer characteristics have been investigated by several researchers. Recently, investigations on multiple stratifications of F layer received an important boost after the quadruple stratification (StF-4) was observed at Palmas (10.3°S, 48.3°W; dip latitude 6.6°S—near-equatorial region), Brazil. The present study reports the latest findings related with the seasonal and solar activity characteristics of the F3 layer and StF-4 near the equatorial region during the period from 2002 to 2006. A significant connection between StF-4 and F3 layer has been noticed, since the StF-4 is always preceded and followed by a F3 layer appearance. However, the F3 layer and the StF-4 present different seasonal and solar cycle variations. At a near-equatorial station Palmas, the F3 layer shows the maximum and minimum occurrences during summer and winter seasons, respectively. On the contrary, the StF-4 presents the maximum and minimum occurrences during winter and summer seasons, respectively. While the F3 layer occurrence is not affected by solar cycle, the StF-4 appearance is instead more frequent during high solar activity. ; Published ; 12116–12125 ; 2A. Fisica dell'alta atmosfera ; JCR Journal ; open

العلاقة: Journal of geophysical research - space physics; 12/121(2016); http://hdl.handle.net/2122/10448Test

الإتاحة: https://doi.org/10.1002/2016JA023580Test
http://hdl.handle.net/2122/10448Test

المؤلفون: Pezzopane, M., Pignalberi, A., Pietrella, M.

المساهمون: Pezzopane, M., Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Pignalberi, A., Università Alma Mater Studiorum Bologna, Pietrella, M.

مصطلحات موضوعية: Sporadic E layer, Mid-latitude ionosphere, Tidal and Planetary wave, Nonlinear interaction, 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous, 01. Atmosphere::01.02. Ionosphere::01.02.02. Dynamics, 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics, 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation, 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques, 05. General::05.07. Space and Planetary sciences::05.07.01. Solar-terrestrial interaction, 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather

الوصف: Spectral analyses are employed to investigate how the diurnal periodicity of the critical frequency of the sporadic E (Es) layer varies with solar activity. The study is based on ionograms recorded at the ionospheric station of Rome (41.8°N, 12.5°E), Italy, from 1976 to 2009, a period of time covering three solar cycles. It was confirmed that the diurnal periodicity is always affected by an amplitude modulation with periods of several days, which is the proof that Es layers are affected indirectly by planetary waves through their non linear interaction with atmospheric tides at lower altitudes. The most striking features coming out from this study is however that this amplitude modulation is greater for high-solar activity than for low-solar activity. ; Published ; 29-35 ; 2A. Fisica dell'alta atmosfera ; 1IT. Reti di monitoraggio e Osservazioni ; 4IT. Banche dati ; JCR Journal ; open

العلاقة: Journal of atmospheric and solar-terrestrial physics; /137(2016); http://hdl.handle.net/2122/10190Test

الإتاحة: https://doi.org/10.1016/j.jastp.2015.11.010Test
http://hdl.handle.net/2122/10190Test