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  • Springer  (3)
  • Wiley Agu  (2)
  • Nature P. G.  (1)
  • 2020-2022  (6)
  • 1
    Publication Date: 2021-10-23
    Print ISSN: 0949-7714
    Electronic ISSN: 1432-1394
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Published by Springer
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  • 2
    Publication Date: 2020-11-20
    Description: The scaling features of electron density fluctuations during the St. Patrick's magnetic storm (17 March 2015) are analyzed to try to characterize the possible turbulent nature of the ionosphere during the development of the geomagnetic storm. The electron density values recorded by two of the three satellites of Swarm constellation during a period of 7 days (16–22 March 2015) around the storm peak are analyzed at middle‐ and high‐latitude regions in both hemispheres. The analysis reveals interesting patterns in the scaling properties of electron density fluctuations and a possible explanation for the occurrence of high values of the Rate of change Of the electron Density Index (RODI). Indeed, the obtained results seem to suggest that very high values of RODI, which describes the structuring of the plasma within a fixed time and is used as an ionospheric disturbance index, are correlated with the antipersistent character of electron density fluctuations and with the values around 5/3 of the power spectral density scaling exponent. These features are independent of the different phases of the analyzed geomagnetic storm and seem to support the idea of a fluid and/or magnetohydrodynamic turbulence as the main responsible of the high values of RODI recorded at high latitudes in the auroral and polar cap regions.
    Description: Published
    Description: e2020JA027934
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2021-05-12
    Description: The present work focuses on the analysis of the scaling features of electron density fluctuations in the mid- and high-latitude topside ionosphere under different conditions of geomagnetic activity. The aim is to understand whether it is possible to identify a proxy that may provide information on the properties of electron density fluctuations and on the possible physical mechanisms at their origin, as for instance, turbulence phenomena. So, we selected about 4 years (April 2014–February 2018) of 1 Hz electron density measurements recorded on-board ESA Swarm A satellite. Using the Auroral Electrojet (AE) index, we identified two different geomagnetic conditions: quiet (AE 〈 50 nT) and active (AE 〉 300 nT). For both datasets, we evaluated the first- and second-order scaling exponents and an intermittency coefficient associated with the electron density fluctuations. Then, the joint probability distribution between each of these quantities and the rate of change of electron density index was also evaluated. We identified two families of plasma density fluctuations characterized by different mean values of both the scaling exponents and the considered ionospheric index, suggesting that different mechanisms (instabilities/turbulent processes) can be responsible for the observed scaling features. Furthermore, a clear different localization of the two families in the magnetic latitude— magnetic local time plane is found and its dependence on geomagnetic activity levels is analyzed. These results may well have a bearing about the capability of recognizing the turbulent character of irregularities using a typical ionospheric plasma irregularity index as a proxy
    Description: Published
    Description: 6183
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Keywords: Turbulence ; High-latitude ionosphere ; electron density fluctuations ; Swarm constellation ; 01.02. Ionosphere
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2020-09-01
    Description: This paper is a final review of the Simplified Ionospheric Regional Model (SIRM) devel- oped as a prototype in the early 1990s and improved in the following years. By means of an algorithm based on the Fourier synthesis, the SIRM model in its prototype version pro- vides predicted monthly median values of the main ionospheric characteristics such as: the ordinary wave critical frequencies (foE, foF1, and foF2) of the E, F1, and F2 ionospheric layers; the lowest virtual height (h’F) of the ordinary trace of the F region; the obliquity factor for a distance of 3000 km (M(3000)F2). Instead, the improved version focuses only on foF2 and M(3000)F2. The SIRM model has been largely employed in the framework of different international research projects as the climatological reference to output foF2 and M(3000)F2 monthly median predictions, but in its SIRMUP version is used also as a nowcasting model and as an intermediate step of complex procedures for a near real- time three-dimensional representation of the ionospheric electron density. In this regard, some results provided by both SIRM and SIRMUP for telecommunication applications are shown. Moreover, the mathematical treatment concerning both the phase correction of the Fourier synthesis and the fundamental steps carried out to define the SIRM algorithm in its final version, never published so far, will be described in detail in dedicated Appendices. Finally, for the first time the SIRM code is now downloadable for the benefit of users.
    Description: Published
    Description: 1143-1178
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Keywords: SIRM ; SIRMUP ; foF2 ; M(3000)F2 ; Regional modelling ; 01.02. Ionosphere
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2021-06-07
    Description: The spatial and temporal dynamics of ionospheric currents are among the most evident manifestations of the interaction between the magnetized plasma of solar origin and the magnetosphere- ionosphere system. In this context, a special role is played by field-aligned currents (FACs), which drive energy and momentum exchanges between the magnetosphere and the ionosphere, deeply affecting the energy balance of the latter. One of the most relevant physical quantities that may help to fully characterize FACs is the ionospheric electrical conductivity. Understanding the features associated with this quantity may contribute to the advancement of knowledge on the mechanisms of solar wind- magnetosphere-ionosphere interaction as well as energy storage and dissipation involved in the space weather phenomena. By extending a previous study, we investigate the dependence of the electrical conductivity parallel to the geomagnetic field on solar and geomagnetic activity. To this aim, we considered a six-year long data set of in-situ electron density and temperature values recorded by the Langmuir probes on board the Swarm satellites in the topside ionosphere. With this large data set, we computed global maps of the parallel electron conductivity under both quiet and disturbed conditions, and for different solar activity levels. In both cases, the International Reference Ionosphere (IRI) model allowed estimating the contribution of particle precipitation to electrical conductivity.
    Description: Published
    Description: e2021JA029138
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2020-07-13
    Description: A possible driver of precipitation of magnetospheric energetic electrons in the high-latitude atmosphere is represented by electromagnetic ion-cyclotron (EMIC) magnetospheric waves. The precipitating particles produce variations, by collision, in the ionized component of the atmosphere, altering its chemistry and electrical conductivity, with a significant impact on the atmospheric processes. In this framework, it would be significant to find experimental evidence of a correspondence between ionospheric electron density irregularities and the occurrence of Ultra-Low-Frequency (ULF) Pc1 geomagnetic pulsations, i.e., the ground signatures of EMIC waves, at high latitudes. In this work, we face this subject by considering a specific case study occurred on 22 February 2007 during quiet magnetospheric conditions. The study is based on the analysis of simultaneous ULF geomagnetic field and Total Electron Content (TEC) measurements recorded at Mario Zucchelli Station in Antarctica. We show that Pc1 pulsations occur in correspondence to solar wind pressure increases and that, at the same time, the ionosphere is characterized by the presence of ionospheric irregularities. We suggest that a possible link between the Pc1 activity and the ionospheric irregularities may be energetic electron precipitations, driven by EMIC waves generated in the compressed magnetosphere, which produce density variations in the ionized component of the atmosphere.
    Description: Published
    Description: id 59
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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