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  • 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous  (23)
  • 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
  • Elsevier Science Limited  (23)
  • AGU  (11)
  • Wiley  (3)
  • American Physical Society
Collection
Keywords
Publisher
Years
  • 1
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    Unusual nighttime impulsive foF2 enhancement below the southern anomaly crest under geomagnetically quiet conditions (2011)
    AGU
    Details
    Publication Date: 2020-12-14
    Description: An unusual nighttime impulsive electron density enhancement was observed on 6 March 2010 over a wide region of South America, below the southern crest of the equatorial anomaly, under low solar activity and quiet geomagnetic conditions. The phenomenon was observed almost simultaneously by the F2 layer critical frequency ( foF2) recorded at three ionospheric stations which are widely distributed in space, namely Cachoeira Paulista (22.4°S, 44.6°W, magnetic latitude 13.4°S), São José dos Campos (23.2°S, 45.9°W, magnetic latitude 14.1°S), Brazil, and Tucumán (26.9°S, 65.4°W, magnetic latitude 16.8°S), Argentina. Although in a more restricted region over Tucumán, the phenomenon was also observed by the total electron content (TEC) maps computed by usingmeasurements from 12 GPS receivers. The investigated phenomenon is very particular because besides being of brief duration, it is characterized by a pronounced compression of the ionosphere. This compression was clearly visible both by the virtual height of the base of the F region (h′F) recorded at the aforementioned ionospheric stations, and by both the vertical electron density profiles and the slab thickness computed over Tucumán. Consequently, neither an enhanced fountain effect nor plasma diffusion from the plasmasphere can be considered as the single cause of this unusual event. A thorough analysis of isoheight and isofrequency ionosonde plots suggest that traveling ionospheric disturbances (TIDs) caused by gravity wave (GW) propagation could have likely played a significant role in causing the phenomenon.
    Description: Published
    Description: A12314
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: 5.4. Banche dati di geomagnetismo, aeronomia, clima e ambiente
    Description: JCR Journal
    Description: open
    Keywords: equatorial ionosphere ; travelling ionospheric disturbance ; ionosphere-atmosphere interactions ; instrument and techniques ; 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::05.07.99. General or miscellaneous ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    20 March 2015 solar eclipse influence on sporadic E layer (2015)
    Elsevier Science Limited
    Details
    Publication Date: 2021-06-07
    Description: This paper shows how the solar eclipse occurred on 20 March 2015 influenced the sporadic E (Es) layer as recorded by the Advanced Ionospheric Sounder by Istituto Nazionale di Geofisica e Vulcanologia (AIS-INGV) ionosondes installed at Rome (41.8°N, 12.5°E) and Gibilmanna (37.9°N, 14.0°E), Italy. In these locations, the solar eclipse was only partial, with the maximum area of the solar disk obscured by the Moon equal to ~54% at Rome and ~45% at Gibilmanna. Nevertheless, it is shown that the strong thermal gradients that usually accompany a solar eclipse, have significantly influenced the Es phenomenology. Specifically, the solar eclipse did not affect the Es layer in terms of its maximum intensity, which is comparable with that of the previous and next day, but rather in terms of its persistence. In fact, both at Rome and Gibilmanna, contrary to what typically happens in March, the Es layer around the solar eclipse time is always present. On the other hand, this persistence is also confirmed by the application of the height–time–intensity (HTI) technique. A detailed analysis of isoheight ionogram plots suggests that traveling ionospheric disturbances (TIDs) likely caused by gravity wave (GW) propagation have played a significant role in causing the persistence of the Es layer.
    Description: Published
    Description: 2064–2072
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 2A. Fisica dell'alta atmosfera
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: JCR Journal
    Description: restricted
    Keywords: Mid-latitude ionosphere ; E sporadic layer ; Solar eclipse ; Gravity wave ; Height–time–intensity technique ; 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 ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Seismic anisotropy reveals focused mantle flow around the Calabrian slab (Southern Italy) (2007)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: SKS splitting at the Calabrian subduction zone, with delay times (δt) up to 3s, reveals the presence of a strong anisotropic fabric. Fast directions (ϕ) are oriented NNE-SSW in the Calabrian Arc (C.A.) and rotate NNW-SSE to the north following the arcuate shape of the subducting plate. We interpret the trench-parallel ϕ as local-scale mantle flow driven by the retrograde motion of the slab; the absence of trench perpendicular ϕ below the Southern Apennines (S.A.) excludes the presence of a seismically detectable return flow at its NE edge. This may be due to the relative youth and limited width of the S.A. slab tear. A possible return flow is identified farther north at the boundary of the S.A. and Central Apennines. Different and weaker anisotropy is present below the Apulian Platform (A.P.). This implies that the influence of the slab rollback in the sub-slab mantle is limited to less then 100 km from the slab.
    Description: Published
    Description: L05302
    Description: JCR Journal
    Description: open
    Keywords: shear-wave splitting, calabrian subduction zone ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 1261235 bytes
    Format: application/pdf
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  • 4
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    Seismotomography of the crust in the transition zone between the southern Tyrrhenian and Sicilian tectonic domains (2008)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: A crustal tomography of seismic wave velocity was performed in the contact zone between the southern Tyrrhenian, Sicilian and Ionian tectonic units, a zone where the lithospheric structure can be expected to furnish evident signatures of dynamics related to the Tyrrhenian subduction process. A dataset of 10241 P and 5597 S readings from 932 local earthquakes recorded between 1978 and 2001 by stations operating in Sicily and Calabria was inverted by the SIMULPS12 algorithm for simultaneous computation of hypocenter parameters and Vp and Vp/Vs three dimensional distributions. The study brought significant improvement in the knowledge of the local velocity structure, furnishing new information useful to better identify the local tectonic units. The results appear to be compatible with the most recent hypotheses regarding the geodynamics of the study region.
    Description: Published
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: open
    Keywords: Continental crust ; Oceanic crust ; Body wave propagation ; Evolution of the Earth: Tomography ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    A method for automatic scaling of sporadic E layers (2007)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: A method for automatic scaling of the maximum frequency and virtual height of a sporadic E layer is presented. A set of ionograms recorded at the ionospheric observatory of Gibilmanna was used to test the performance of the algorithm. The test was performed by comparing the data obtained automatically with the values scaled by an operator.
    Description: Published
    Description: RS2012
    Description: 1.7. Osservazioni di aeronomia
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: ionograms ; automatic scaling ; Autoscala ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Scintillation modeling using in situ data (2007)
    AGU
    Details
    Publication Date: 2017-04-03
    Description: Satellite in situ measurements of plasma (electron) density fluctuations provide direct information about the structure and morphology of irregularities that are responsible for scintillation of radio waves on transionospheric links. When supplemented with the ionosphere model and irregularity anisotropy model, they can be applied to model morphology of scintillation provided a suitable propagation model is used. In this paper we present a scintillation climatological model for the Northern Hemisphere high-latitude ionosphere, which makes use of the Dynamics Explorer 2 retarding potential analyzer plasma density data, IRI ionosphere model, and the phase screen propagation model. An important aspect of our work is that we derived from the satellite data not just the turbulence strength parameter Cs but also the spectral index p, which influences the scintillation level as well. We discuss the magnetic activity, season, magnetic time, and latitude dependence of these parameters. We were able to reproduce successfully the observed scintillation intensity diurnal and seasonal variations. The model satisfactorily describes the expansion of the scintillation zone under magnetically disturbed conditions and reproduces the dawn-dusk asymmetry in the scintillation intensity. The results demonstrate the usefulness of the proposed approach.
    Description: Published
    Description: RS1002
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: scintillations modeling ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    P-wave deep velocity structure of the Southern Tyrrhenian Subduction Zone from nonlinear teleseismic traveltime tomography (2007)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: A new 3-D model for the P-wave velocity structure of the Southern Tyrrhenian Subduction Zone (STSZ) is determined from nonlinear inversion of relative arrival times of teleseismic events. The data used in the imaging are the travel time residuals of both direct, P and PKPdf, and secondary pP, sP, PcP, PKPbc phases, computed with respect to the global 1-D velocity model ak135. 2308 teleseismic waveforms were collected for this study from 109 events recorded by the Italian National Seismic Network (RSNC) during 1988-1998. The velocity perturbation eld is reconstructed gradually by means an iterative sequence of linearized inversions, incorporating a 3-D minimum travel time ray tracing. The tomographic images reveal a broad highvelocity zone dominating the pattern of lateral variations beneath the Southern Tyrrhenian Sea and Calabria. This fast structure extends laterally for a maximum of 350 km, from northern Sicily to southern Campania, and vertically for at least 400 km, from the uppermost mantle down to 500 km depth. Below 350 km the geometry of the depicted slab is characterized by horizontal deflection of the subducting lithosphere towards the central Tyrrhenian basin.
    Description: Published
    Description: 3709-3712
    Description: JCR Journal
    Description: reserved
    Keywords: P-wave velocity ; teleseismic tomography ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Instantaneous space-weighted ionospheric regional model for instantaneous mapping of the critical frequency of the F2 layer in the European region (2007)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: An instantaneous space-weighted ionospheric regional model (ISWIRM) for the regional now-casting of the critical frequency of the F2 layer (foF2) has been developed. The geographical area of applicability of the model is ranged between 35°N–70°N and 5°W–40°E. Inside this region the hourly values of foF2 are obtained, correcting the monthly medians values of foF2 predicted by the space-weighted ionospheric local model (SWILM) on the basis of hourly observations of foF2 coming from four reference stations (Rome, Chilton, Lycksele, and Loparskaya (or Sodankyla)). The performance of the model, evaluated at four testing stations (Tortosa, Juliusruh, Uppsala, and Kiruna) during some periods characterized by strong solar and geomagnetic activity, can be considered satisfactory, given that the hourly values of the residuals are almost always below 1 MHz. A comparison between ISWIRM’s performance using manually validated and autoscaled data of foF2 and SWILM’s performance was made for two disturbed periods. One example of instantaneous ionospheric mapping of foF2 relative to the selected disturbed periods is also shown.
    Description: Published
    Description: RS1005,
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: ionosphere, now casting models ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Nonlinear P-wave tomography of subducted lithosphere beneath central-southern Apennines (Italy) (2007)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: We present new tomographic images for the Pwave velocity structure in the upper mantle beneath centralsouthern Apennines down to 510 km depth. The model is computed by nonlinear inversion of relative arrival times of both direct and secondary teleseismic phases, handpicked from over 2800 waveforms recorded by the Italian seismic network during 1988-2000. Beneath central Apennines, the images reveal a continuous, SW-dipping high-velocity body, from 150 km down to 500 km. At shallower depths, a pronounced low-velocity zone is recognized from the uppermost mantle beneath the Apenninic belt down to 200 km below the Tyrrhenian area. This feature is proposed to affect the seismic structure of the downgoing slab, weakening its velocity signature. Beneath southern Apennines, highvelocity anomalies are reconstructed in the uppermost mantle of the Apulian foreland and below the belt in the range 100 400 km. Low-velocity regions, interpreted as due to asthenospheric upwelling, are recovered above or across the fast structures, as at the southeastern end of the Apennines where a possible complete slab breako is suggested.
    Description: Published
    Description: 4387-4390
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: P-wave tomography ; lithosphere ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Automatic scaling of critical frequency foF2 and MUF(3000)F2: A comparison between Autoscala and ARTIST 4.5 on Rome data (2007)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: The performances of Autoscala and ARTIST 4.5 were comparatively evaluated using a large database of 6098 ionograms recorded from September 2005 to June 2006 by the digisonde DPS4 at the Rome ionospheric station. Results of comparisons between automatically and manually scaled data are shown for both programs highlighting the different behaviours. The Autoscala and ARTIST 4.5 values of foF2 and MUF(3000)F2 both agree with the hand-scaled values for ~95% of ionograms. For the other ~5% of ionograms, which the manual scaler classed as unscalable, ARTIST 4.5 usually gave invalid results, whereas Autoscala usually gave no result. The data recorded by the ionosondes DPS4 (interpreted by ARTIST 4.5) and AIS-INGV (interpreted by Autoscala) during 3 geomagnetic storms were also analysed. Ionograms with typical errors both for Autoscala and ARTIST 4.5 are displayed.
    Description: Published
    Description: RS4003
    Description: 1.7. Osservazioni di aeronomia
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: Ionograms ; ARTIST ; Autoscala ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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