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  • Copernicus  (5)
  • Elsevier Science Limited  (3)
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Years
  • 1
    Publication Date: 2005-05-27
    Description: In this paper a method for real-time updating of ionospheric electron density profile, N(h), over Europe using an ionospheric model and real-time measurements at ionosonde locations is presented. The N(h) profile update over European area has been simulated with the IRI-2000 ionospheric model and real-time N(h) profiles obtained from the EU COST271 Action Space Weather Database. Preliminary findings are shown for the geomagnetically quiet day on 4 May 2003 and disturbed day on 24 May 2002. Results are discussed in the context of real-time N(h) profile updating capabilities and effectiveness.
    Print ISSN: 1684-9965
    Electronic ISSN: 1684-9973
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 2
    Publication Date: 2005-11-22
    Print ISSN: 0992-7689
    Electronic ISSN: 1432-0576
    Topics: Geosciences , Physics
    Published by Copernicus on behalf of European Geosciences Union.
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  • 3
    Publication Date: 1999-08-31
    Description: The CRISTA/MAHRSI experiment on board a space shuttle was accompanied by a broad campaign of rocket, balloon and ground-based measurements. Supporting lower ionospheric ground-based measurements were run in Europe and Eastern Asia between 1 October-30 November, 1994. Results of comparisons with long ionospheric data series together with short-term comparisons inside the interval October-November, 1994, showed that the upper middle atmosphere  (h = 80-100 km) at middle latitudes of the Northern Hemisphere in the interval of the CRISTA/MAHRSI experiment (4-12 November, 1994) was very close to its expected climatological state. In other words, the average results of the experiment can be used as climatological data, at least for the given area/altitudes. The role of solar/geomagnetic and "meteorological" control of the lower ionosphere is investigated and compared with the results of MAP/WINE, MAC/SINE and DYANA campaigns. The effects of both solar/geomagnetic and global meteorological factors on the lower ionosphere are found to be weak during autumn 1994 compared to those in MAP/WINE and DYANA winters, and they are even slightly weaker than those in MAP/SINE summer. The comparison of the four campaigns suggests the following overall pattern: in winter the lower ionosphere at northern middle latitudes appears to be fairly well "meteorologically" controlled with a very weak solar influence. In summer, solar influence is somewhat stronger and dominates the weak "meteorological" influence, but the overall solar/meteorological control is weaker than in winter. In autumn we find the weakest overall solar/meteorological control, local effects evidently dominate.Key words. Ionosphere (ionosphere · atmosphere interactions; mid-latitude ionosphere)
    Print ISSN: 0992-7689
    Electronic ISSN: 1432-0576
    Topics: Geosciences , Physics
    Published by Copernicus on behalf of European Geosciences Union.
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  • 4
    Publication Date: 2006-07-03
    Description: We present an analysis of ULF geomagnetic field fluctuations at low latitudes during the first CAWSES campaign (29 March-3 April 2004). During the whole campaign, mainly in the prenoon sector, a moderate Pc3-4 pulsation activity is observed, clearly related to interplanetary upstream waves. On 3 April, in correspondence to the Earth's arrival of a coronal mass ejection, two SIs are observed whose waveforms are indicative of a contribution of the high-latitude ionospheric currents to the low-latitude ground field. During the following geomagnetic storm, low frequency (Pc5) waves are observed at discrete frequencies. Their correspondence with the same frequencies detected in the radial components of the interplanetary magnetic field and solar wind speed suggests that Alfvénic solar wind fluctuations may act as direct drivers of magnetospheric fluctuations. A cross-phase analysis, using different pairs of stations, is also presented for identifying field line resonant frequencies and monitoring changes in plasmaspheric mass density. Lastly, an analysis of ionospheric vertical soundings, measured at the Rome ionosonde station (41.8° N, 12.5° E), and vertical TEC measurements deduced from GPS signals within an European network shows the relation between the ULF resonances in the inner magnetosphere and thermal plasma density variations during geomagnetically quiet conditions, in contrast to various storm phases at the end of the CAWSES campaign.
    Print ISSN: 0992-7689
    Electronic ISSN: 1432-0576
    Topics: Geosciences , Physics
    Published by Copernicus on behalf of European Geosciences Union.
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  • 5
    Publication Date: 2008-02-26
    Description: The eSWua project is based on measurements performed by all the instruments installed by the upper atmosphere physics group of the Istituto Nazionale di Geofisica e Vulcanologia, Italy and on all the related studies. The aim is the realization of a hardware-software system to standardize historical and real-time observations for different instruments. An interactive Web site, supported by a well organized database, can be a powerful tool for the scientific and technological community in the field of telecommunications and space weather. The most common and useful database type for our purposes is the relational one, in which data are organized in tables for petabytes data archiving and the complete flexibility in data retrieving. The project started in June 2005 and will last till August 2007. In the first phase the major effort has been focused on the design of hardware and database architecture. The first two databases related to the DPS4 digisonde and GISTM measurements are complete concerning populating, tests and output procedures. Details on the structure and Web tools concerning these two databases are presented, as well as the general description of the project and technical features.
    Print ISSN: 0992-7689
    Electronic ISSN: 1432-0576
    Topics: Geosciences , Physics
    Published by Copernicus on behalf of European Geosciences Union.
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  • 6
    Publication Date: 2017-04-04
    Description: The present paper proposes to discuss the ionospheric absorption, assuming a quasi-flat layered ionospheric medium, with small horizontal gradients. A recent complex eikonal model [Settimi et al., 2013b] is applied, useful to calculate the absorption due to the ionospheric D-layer, which can be approximately characterized by a linearized analytical profile of complex refractive index, covering a short range of heights between h1= 50 km and h2= 90 km. Moreover, Settimi et al. [2013c] have already compared the complex eikonal model for the D-layer with the analytical Chapman’s profile of ionospheric electron density; the corresponding absorption coefficient is more accurate than Rawer’s theory [1976] in the range of middle critical frequencies. Finally, in this paper, the simple complex eikonal equations, in quasi-longitudinal (QL) approximation, for calculating the non-deviative absorption coefficient due to the propagation across the D-layer are encoded into a so called COMPLEIK (COMPLex EIKonal) subroutine of the IONORT (IONOspheric Ray-Tracing) program [Azzarone et al., 2012]. The IONORT program, which simulates the three-dimensional (3-D) ray-tracing for high frequencies (HF) waves in the ionosphere, runs on the assimilative ISP (IRI-SIRMUP-P) discrete model over the Mediterranean area [Pezzopane et al., 2011]. As main outcome of the paper, the simple COMPLEIK algorithm is compared to the more elaborate semi-empirical ICEPAC formula [Stewart, undated], which refers to various phenomenological parameters such as the critical frequency of E-layer. COMPLEIK is reliable just like the ICEPAC, with the advantage of being implemented more directly. Indeed, the complex eikonal model depends just on some parameters of the electron density profile, which are numerically calculable, such as the maximum height.
    Description: Published
    Description: 201-218
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Description: partially_open
    Keywords: Ionospheric D-layer ; Quasi-Longitudinal propagation ; non-deviative absorption ; ICEPAC formula ; ISP-IONORT ; Complex Eikonal theory ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.01. Ion chemistry and composition ; 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous ; 05. General::05.07. Space and Planetary sciences::05.07.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2020-02-24
    Description: This paper describes the three-dimensional (3-D) electron density mapping of the ionosphere given as output by the assimilative IRI-SIRMUP-P (ISP) model for three different geomagnetic storms. Results of the 3-D model are shown by comparing the electron density profiles given by the model with the ones measured at two testing ionospheric stations: Roquetes (40.8 °N,0.5 °E), Spain, and San Vito (40.6°N,17.8 °E), Italy. The reference ionospheric stations from which the autoscaled foF2 and M(3000)F2 data as well as the real-time vertical electron density profiles are assimilated by the ISP model are those of El Arenosillo (37.1 °N,353.3° E), Spain, Rome (41.8 °N,12.5 °E), and Gibilmanna (37.9° N,14.0 °E), Italy. Overall, the representation of the ionosphere made by the ISP model is better than the climatological representation made by only the IRI-URSI and the IRI-CCIR models. However, there are few cases for which the assimilation of the autoscaled data from the reference stations causes either a strong underestimation or a strong overestimation of the real conditions of the ionosphere, which is in these cases better represented by only the IRI-URSI model. This ISP misrepresentation is mainly due to the fact that the reference ionospheric stations covering the region mapped by the model turn out to be few, especially for disturbed periods when the ionosphere is very variable both in time and in space and hence a larger number of stations would be required. The inclusion of new additional reference ionospheric stations could surely smooth out this concern.
    Description: Published
    Description: 1726-1736
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: open
    Keywords: Disturbed ionosphere ; Electron density ; Ionogram ; IRI ; 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::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2020-02-24
    Description: In this paper we analyze the behaviour of the critical frequency of the F2 region of the ionosphere(foF2)and the height of the maximum density of free electrons in F2 region(hmF2)overTucumán(26.91S,294.61E), during the deep solar minimum occurred in 2008–2009. Data used were compared with those obtained at solar minimum observed in 1975–1976. In addition, we check the validity of theI nternational Reference Ionosphere model(IRI), in the version 2012, to predict the maximum free electron density in the ionosphere(NmF2)above the mentioned station, for very low solar activity. The results show that: (a) Ionization was lowest for recent solar minimum.(b)The semmianual anomaly which are present in the behaviour of foF2 at times of increased solar activity, was not clearly observed during the period 2008–2009. This phenomenon could be related with the very low solar activity for that period, confirming the relationship of the amplitude of this anomaly with the solar activity reported by other authors.(c)In most cases, the values of hmF2 recorded in the deep solar minimum are lower than those observed in the period 1975–1976, suggesting a decrease in the height of the ionosphere in the course of time, which could be related to the greenhouse effect in the atmosphere and the anomalously low solar extreme-ultraviolet irradiance.(d)IRI predictions show significant deviations from the experimental values, indicating the need for improvements in the model.
    Description: Published
    Description: 89-98
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Description: restricted
    Keywords: F2 region ; solar minimum ; IRI 2012 ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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