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  • 11
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    Ground and satellite-based observations of ionospheric plasma bubbles and blobs at 5.65° latitude in the Brazilian sector (2021)
    Elsevier
    Details
    Publication Date: 2021-02-01
    Print ISSN: 0273-1177
    Electronic ISSN: 1879-1948
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Elsevier
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  • 12
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    A New Ionospheric Index to Investigate Electron Temperature Small-Scale Variations in the Topside Ionosphere (2021)
    Molecular Diversity Preservation International
    Details
    Publication Date: 2021-08-06
    Description: The electron temperature (Te) behavior at small scales (both spatial and temporal) in the topside ionosphere is investigated through in situ observations collected by Langmuir Probes on-board the European Space Agency Swarm satellites from the beginning of 2014 to the end of 2020. Te observations are employed to calculate the Rate Of change of electron TEmperature Index (ROTEI), which represents the standard deviation of the Te time derivative calculated over a window of fixed width. As a consequence, ROTEI provides a description of the small-scale variations of Te along the Swarm satellites orbit. The extension of the dataset and the orbital configuration of the Swarm satellites allowed us to perform a statistical analysis of ROTEI to unveil its mean spatial, diurnal, seasonal, and solar activity variations. The main ROTEI statistical trends are presented and discussed in the light of the current knowledge of the phenomena affecting the distribution and dynamics of the ionospheric plasma, which play a key role in triggering Te small-scale variations. The appearance of unexpected high values of ROTEI at mid and low latitudes for specific magnetic local time sectors is revealed and discussed in association with the presence of Te spikes recorded by Swarm satellites under very specific conditions.
    Electronic ISSN: 2218-1997
    Topics: Physics
    Published by Molecular Diversity Preservation International
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  • 13
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    On the link between the topside ionospheric effective scale height and the plasma ambipolar diffusion, theory and preliminary results (2020)
    Springer Nature
    Details
    Publication Date: 2020-10-16
    Description: Over the years, an amount of models relying on effective parameters were implemented in the challenging issue of the topside ionosphere description. These models are based on different analytical functions, but all of them depend on a parameter called effective scale height, that is deduced from topside electron density measurements. As their names state, they are effective in reproducing the topside electron density profile only when applied to the analytical function used to derive them. Then, in principle, they do not have any physical meaning. It is the goal of this paper to mathematically link the effective scale height modeled through the Epstein layer to the vertical scale height theoretically deduced from the plasma ambipolar diffusion theory. Firstly, effective and theoretical scale heights are linked through a mathematical relation by showing that they tend to each other in the topside ionosphere. Secondly, their connection is preliminarily demonstrated by calculating effective scale height values from the entire COSMIC/FORMOSAT-3 radio occultation dataset. Thirdly, a possible connection between the vertical gradient of the topside scale height (as obtained by COSMIC/FORMOSAT-3 satellites) and the electron temperature (as obtained by ESA Swarm B satellite) is studied by highlighting corresponding similarities in the diurnal, seasonal, solar activity, and latitudinal variability.
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 14
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    Midlatitude climatology of the ionospheric equivalent slab thickness over two solar cycles (2021)
    Springer
    Details
    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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  • 15
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    On some features characterizing the plasmasphere-magnetosphere-ionosphere system during the geomagnetic storm of 27 May 2017 (2019)
    Details
    Publication Date: 2020-12-17
    Description: This paper presents how the magnetosphere-plasmasphere-ionosphere system was affected as a whole during the geomagnetic storm peaking on 27 May 2017. The interplanetary conditions, the magnetospheric response in terms of the magnetopause motion, and the ionospheric current flow pattern were investigated using data, respectively, from the WIND spacecraft, from GOES15, GOES13, THEMIS E, THEMIS D and THEMIS A satellites and from the INTERMAGNET magnetometer array. The main objective of the work is to investigate the plasmaspheric dynamics under disturbed conditions and its possible relation to the ionospheric one; to reach this goal, the equatorial plasma mass densities derived from geomagnetic field line resonance observations at the European quasi-Meridional Magnetometer Array (EMMA) and total electron content values obtained through three GPS receivers close to EMMA were jointly considered. Despite the complexity of physical mechanisms behind them, we found a similarity between the ionospheric and plasmaspheric characteristic recovery times. Specifically, the ionospheric characteristic time turned out to be ~ 1.5 days, ~ 2 days and ~ 3.1 days, respectively, at L ~ 3, L ~ 4 and L ~ 5, while the plasmaspheric one, for similar L values, ranged from ~ 1 day to more than 4 days.
    Description: Published
    Description: ID 77
    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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  • 16
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    Effective Solar Indices for Ionospheric Modeling: A Review and a Proposal for a Real-Time Regional IRI (2018)
    Details
    Publication Date: 2021-03-02
    Description: The first part of this paper reviews methods using effective solar indices to update a background ionospheric model focusing on those employing the Kriging method to perform the spatial interpolation. Then, it proposes a method to update the International Reference Ionosphere (IRI) model through the assimilation of data collected by a European ionosonde network. The method, called International Reference Ionosphere UPdate (IRI UP), that can potentially operate in real time, is mathematically described and validated for the period 9–25 March 2015 (a time window including the well-known St. Patrick storm occurred on 17 March), using IRI and IRI Real Time Assimilative Model (IRTAM) models as the reference. It relies on foF2 and M(3000)F2 ionospheric characteristics, recorded routinely by a network of 12 European ionosonde stations, which are used to calculate for each station effective values of IRI indices IG12 and R12 (identified as IG12eff and R12eff ); then, starting from this discrete dataset of values, two-dimensional (2D) maps of IG12eff and R12eff are generated through the universal Kriging method. Five variogram models are proposed and tested statistically to select the best performer for each effective index. Then, computed maps of IG12eff and R12eff are used in the IRI model to synthesize updated values of foF2 and hmF2. To evaluate the ability of the proposed method to reproduce rapid local changes that are common under disturbed conditions, quality metrics are calculated for two test stations whose measurements were not assimilated in IRI UP, Fairford (51.7°N, 1.5°W) and San Vito (40.6°N, 17.8°E), for IRI, IRI UP, and IRTAM models. The proposed method turns out to be very effective under highly disturbed conditions, with significant improvements of the foF2 representation and noticeable improvements of the hmF2 one. Important improvements have been verified also for quiet and moderately disturbed conditions. A visual analysis of foF2 and hmF2 maps highlights the ability of the IRI UP method to catch small-scale changes occurring under disturbed conditions which are not seen by IRI.
    Description: Published
    Description: 125-167
    Description: 2A. Fisica dell'alta atmosfera
    Description: 1IT. Reti di monitoraggio
    Description: 4IT. Banche dati
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 17
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    Investigation of the Physical Processes Involved in GNSS Amplitude Scintillations at High Latitude: A Case Study (2021)
    MDPI
    Details
    Publication Date: 2021-07-01
    Description: The storm onset on 7 September 2017, triggered several variations in the ionospheric electron density, causing severe phase fluctuations at polar latitudes in both hemispheres. In addition, although quite rare at high latitudes, clear amplitude scintillations were recorded by two Global Navigation Satellite System receivers during the main phase of the storm. This work attempted to investigate the physical mechanisms triggering the observed amplitude scintillations, with the aim of identifying the conditions favoring such events. We investigated the ionospheric background and other conditions that prevailed when the irregularities formed and moved, following a multiobservations approach. Specifically, we combined information from scintillation parameters and recorded by multi-constellation (GPS, GLONASS and Galileo) receivers located at Concordia station (75.10 S, 123.35 E) and SANAE IV base (71.67 S, 2.84 W), with measurements acquired by the Special Sensor Ultraviolet Spectrographic Imager on board the Defense Meteorological Satellite Program satellites, the Super Dual Auroral Radar Network, the Swarm constellation and groundbased magnetometers. Besides confirming the high degree of complexity of the ionospheric dynamics, our multi-instrument observation identified the physical conditions that likely favor the occurrence of amplitude scintillations at high latitudes. Results suggest that the necessary conditions for the observation of this type of scintillation in high-latitude regions are high levels of ionization and a strong variability of plasma dynamics. Both of these conditions are typically featured during high solar activity.
    Description: Published
    Description: 2493
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 18
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    Can an impulsive variation of the solar wind plasma pressure trigger a plasma bubble? A case study based on CSES, Swarm and THEMIS data (2021)
    Elsevier
    Details
    Publication Date: 2021-06-21
    Description: During the August 25, 2018 geomagnetic storm, the new borne CSES-01 satellite and the Swarm A satellite detected a really large equatorial plasma bubble (EPB) in the post-midnight sector over western Africa. We investigated the features of this deep ionospheric plasma depletion using data from the Langmuir probes on-board CSES-01 and Swarm A satellites, and data from the high-precision magnetometer and the electric field detector instruments on-board CSES-01. Using also plasma and magnetic field data from THEMIS-E satellite we found that, during the passage of the magnetic cloud that drove the geomagnetic storm, an impulsive variation lasting about ten minutes characterized the solar wind (SW) pressure. The analysis of the delay time, between the occurrence of such impulsive variation and the detection of the plasma bubble, suggests a possible link between the SW pressure impulsive variation as identified by THEMIS-E and the generation of the EPB as detected by CSES-01 and Swarm A. We put forward the hypothesis that the SW pressure impulsive variation might have triggered an eastward prompt penetrating electric field that propagated from high to equatorial latitudes, overlapping in the nightside region to the zonal westward electric field, causing either a reduction or an inversion, at the base of the EPB triggering.
    Description: Published
    Description: 35-45
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 2A. Fisica dell'alta atmosfera
    Description: 5IT. Osservazioni satellitari
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 19
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    Modeling the topside ionosphere by means of electron density values as recorded by the Swarm satellites constellation (2020)
    Details
    Publication Date: 2020-10-26
    Description: An empirical method to model the ionospheric topside vertical electron density profile over the European region is proposed. The method is based on electron density values recorded by Langmuir Probes on board Swarm satellites, and on foF2 and hmF2 values provided by IRI UP (International Reference Ionosphere UPdate), which is a method developed to update the IRI (International Reference Ionosphere) model relying on the assimilation of ionospheric data routinely recorded by a network of European ionosonde stations. Topside effective scale heights are calculated by fitting some definite analytical functions (α-Chapman, β-Chapman, Epstein and Exponential) through the values recorded by Swarm and the ones outputted by IRI UP, with the assumption that the effective scale height is constant in the altitude range considered. Calculated effective scale heights are then modeled as a function of the F2-layer peak characteristics, foF2 and hmF2. A statistical comparison with COSMIC/FORMOSAT-3 collected Radio Occultation profiles is carried out to assess the validity of the proposed method, and to investigate which of the considered topside profilers is the best one.
    Description: Published
    Description: id 114
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 20
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    A three-dimensional regional assimilative model of the ionospheric electron density (2020)
    Details
    Publication Date: 2020-10-26
    Description: The focus of this thesis is on the development, implementation, and validation of a three-dimensional regional assimilative model of the ionospheric electron density. Empirical climatological models, like the International Reference Ionosphere (IRI) model (Bilitza et al. 2017), cannot predict the whole ionospheric variability, specifically under disturbed magnetic conditions. The model presented in this work has the purpose to improve the IRI description by implementing a data assimilation procedure, based on ionospheric measurements collected by several ground-based or satellite-based instruments. The first phase of the development of the model, called IRI UPdate (IRI UP), is devoted to update the IRI model by ingesting effective indices (IG12eff and R12eff) calculated after assimilating F2 layer characteristics values, measured by a network of ionosondes or derived by vertical total electron content values measured by a network of Global Navigational Satellite Systems receivers. The ingestion of effective indices in the IRI model allows to significantly improve the F2 layer peak density and height description. Being the F2 layer peak an anchor point for the whole IRI’s vertical electron density profile, such procedure allows to update the whole profile. The second phase of the development of the model is devoted to improve the modeling of the topside part of the ionospheric vertical electron density profile by making use of the IRI UP method and in-situ measurements collected by Swarm satellites. Finally, a procedure called IonoPy, embedding the two aforementioned steps, assimilates the whole bottomside electron density profile measured by an ionosonde, thus further improving the ionospheric plasma description in the bottomside ionosphere. All the procedures described in this thesis have been tested and validated by comparing them with other similar models or with independent datasets, for both quiet and disturbed conditions.
    Description: Dipartimento di Fisica e Astronomia, Universit`a di Bologna Alma Mater Studiorum Bologna, Italy
    Description: Published
    Description: 2A. Fisica dell'alta atmosfera
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: thesis
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