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  • 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous  (4)
  • 01. Atmosphere::01.03. Magnetosphere::01.03.03. Magnetospheric physics  (4)
  • American Geophysical Union  (7)
  • Elsevier
  • 2015-2019  (7)
  • 1
    Publication Date: 2021-02-10
    Description: Moore (1964) in a letter published in Nature reported disturbances in geomagnetic field data prior to the 27 March 1964 Alaska earthquake. After the publication of this report, many papers have shown magnetic changes preceding earthquakes. However, a causal relationship between preearthquake magnetic changes and impending earthquakes has never been demonstrated. As a consequence, after 50 years, magnetic disturbances in the geomagnetic field are still candidate precursory phenomena. Some researchers consider the investigation of ultra low frequency (ULF: 0.001–10 Hz) magnetic data the correct approach for identifying precursory signatures of earthquakes. Other researchers, instead, have recently reviewed many published ULF magnetic changes that preceded earthquakes and have shown that these are not actual precursors. The recent studies by Currie and Waters (2014) and Han et al. (2014) aim to provide relevant new findings in the search for ULF magnetic precursory signals. However, in order to contribute to science, alleged precursors must be shown to be valid and reproducible by objective testing. Here we will briefly discuss the state of the art in the search for ULF magnetic precursors, paying special attention to the recent findings of Currie and Waters (2014) and Han et al. (2014). We do not see in these two reports significant evidence that may support the observation of precursory signatures of earthquakes in ULF magnetic records.
    Description: Published
    Description: 10289–10304
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Geomagnetic field ; Magnetic anomalies ; Earthquake precursors ; 01. Atmosphere::01.03. Magnetosphere::01.03.03. Magnetospheric physics ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: We report a statistical analysis of low-frequency magnetic variations (magnetic pulsations, 0.8–7 mHz) at South Pole (74 S corrected geomagnetic latitude) and Terra Nova Bay (80 S) during 1996. The results show that at South Pole (at cusp latitudes) the pulsation power exhibits two maxima during the day, one in the local premidnight and the other in the morning. The first maximum disappears when the analysis is restricted to northward interplanetary magnetic field conditions (Bz 〉 1 nT), suggesting that it might be associated to substorm phenomena. During closed magnetospheric conditions, when the cusp is expected to be located poleward with respect to the station, the spectral and polarization characteristics of pulsations between 1 and 3 mHz suggest that resonant oscillations of the outermost closed field lines commonly occur at South Pole in the local morning. At Terra Nova Bay, in the polar cap, the pulsation power is much lower and its diurnal variation is characterized by a single maximum, which occurs around local noon, when the station approaches the cusp. The corresponding polarization pattern indicates that Terra Nova Bay is always located poleward with respect to resonant field lines.
    Description: Published
    Description: A02205
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: geomagnetic pulsations ; magnetospheric dynamics ; 01. Atmosphere::01.03. Magnetosphere::01.03.03. Magnetospheric physics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2017-04-04
    Description: Two-dimensional (2-D) statistical distributions of spectral power and coherence of polar geomagnetic variations with quasi-periods about 10 min are analyzed using data from magnetometer arrays in Antarctica. Examination of the 2-D patterns of spectral power and coherence shows the occurrence of significant variations in geomagnetic power levels but with low spatial coherence near the cusp projection and in the auroral region. At the same time, low-amplitude pulsations, which we coin Picap3 pulsations, are very coherent throughout the polar cap. The region occupied by coherent Picap3 pulsations is shifted toward local MLT night from the geomagnetic pole and is decoupled from the regions of auroral and cusp ULF activity. The spectral power varies with time at polar latitudes in a manner different from that at auroral latitudes. Diurnal variations of power at different stations at the same geomagnetic latitude exhibit different behavior depending on the station’s position relative to geomagnetic and geographic poles. This asymmetry is shown to be partly attributed to the variations of the ionospheric conductance. The primary source of polar pulsations is probably related to intermittent magnetosheath turbulence and tail lobe oscillations, though a particular propagation mechanism has not as yet been identified
    Description: Published
    Description: A03222
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: geomagnetic pulsations, polar cap ; 01. Atmosphere::01.03. Magnetosphere::01.03.03. Magnetospheric physics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2022-03-01
    Description: The innovative geometry of European Space Agency Swarm constellation opens the way for new investigations based on magnetic data. Since the knowledge of a vector field on two spherical surfaces allows calculating its curl, we propose a new technique to estimate the curl of the ionospheric magnetic field measured by Swarm satellites A and B, orbiting the Earth at two different altitudes from March to September 2014. Using this technique, we mapped the amplitude of the radial, meridional, and zonal components and of total intensity of the ionospheric current density at the satellite's altitudes, i.e., the F region of the ionosphere, during two local nighttime intervals: before and after midnight. Most of the obtained results are consistent with some of the known features of nighttime F region currents; others need further investigation. The proposed technique could contribute in selecting magnetic data with minimum contamination from nighttime F region electric currents for magnetic modeling purposes.
    Description: Published
    Description: 6162-6169
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Swarm magnetic data ; current density ; F region ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.01. Data processing
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2022-02-16
    Description: 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.
    Description: Published
    Description: 12116–12125
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Description: open
    Keywords: 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2022-02-16
    Description: The present study investigates the ionospheric total electron content (TEC) and F-layer response in the Southern Hemisphere equatorial, low, and middle latitudes due to major sudden stratospheric warming (SSW) event, which took place during January–February 2009 in the Northern Hemisphere. In this study, using 17 ground-based dual frequency GPS stations and two ionosonde stations spanning latitudes from 2.8°N to 53.8°S, longitudes from 36.7°W to 67.8°W over the South American sector, it is observed that the ionosphere was significantly disturbed by the SSW event from the equator to the midlatitudes. During day of year 26 and 27 at 14:00 UT, the TEC was two times larger than that observed during average quiet days. The vertical TEC at all 17 GPS and two ionosonde stations shows significant deviations lasting for several days after the SSWtemperature peak. Using one GPS station located at Rio Grande (53.8°S, 67.8°W, midlatitude South America sector), it is reported for the first time that the midlatitude in the Southern Hemisphere was disturbed by the SSW event in the Northern Hemisphere.
    Description: Published
    Description: 7889–7902
    Description: 2A. Fisica dell'alta atmosfera
    Description: 4A. Clima e Oceani
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: open
    Keywords: sudden stratospheric warming ; equatorial, low, and middle latitude ionosphere ; GPS ; ionosonde ; TEC ; 01. Atmosphere::01.01. Atmosphere::01.01.99. General or miscellaneous ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics ; 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::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2022-11-23
    Description: We investigate the geospace response to the 2015 St. Patrickˈs Day storm leveraging on instruments spread over Southeast Asia (SEA), covering a wide longitudinal sector of the low-latitude ionosphere. A regional characterization of the storm is provided, identifying the peculiarities of ionospheric irregularity formation. The novelties of this work are the characterization in a broad longitudinal range and the methodology relying on the integration of data acquired by Global Navigation Satellite System (GNSS) receivers, magnetometers, ionosondes, and Swarm satellites. This work is a legacy of the project EquatoRial Ionosphere Characterization in Asia (ERICA). ERICA aimed to capture the features of both crests of the equatorial ionospheric anomaly (EIA) and trough (EIT) by means of a dedicated measurement campaign. The campaign lasted from March to October 2015 and was able to observe the ionospheric variability causing effects on radio systems, GNSS in particular. The multiinstrumental and multiparametric observations of the region enabled an in-depth investigation of the response to the largest geomagnetic storm of the current solar cycle in a region scarcely reported in literature. Our work discusses the comparison between northern and southern crests of the EIA in the SEA region. The observations recorded positive and negative ionospheric storms, spread F conditions, scintillation enhancement and inhibition, and total electron content variability. The ancillary information on the local magnetic field highlights the variety of ionospheric perturbations during the different storm phases. The combined use of ionospheric bottomside, topside, and integrated information points out how the storm affects the F layer altitude and the consequent enhancement/suppression of scintillations.
    Description: Published
    Description: 12211–12233
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 2A. Fisica dell'alta atmosfera
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: 5IT. Osservazioni satellitari
    Description: JCR Journal
    Description: open
    Keywords: Saint Patrickˈs Day storm ; scintillation enhancement/suppression ; equatorial ionospheric anomaly ; positive and negative ionospheric storms ; spread F ; total electron content variability ; 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 ; 01. Atmosphere::01.02. Ionosphere::01.02.07. Scintillations ; 01. Atmosphere::01.03. Magnetosphere::01.03.99. General or miscellaneous ; 01. Atmosphere::01.03. Magnetosphere::01.03.02. Magnetic storms ; 01. Atmosphere::01.03. Magnetosphere::01.03.03. Magnetospheric physics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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