1,721,034 research outputs found
Artificial neural network applications in ionospheric studies
No full textThe ionosphere of Earth exhibits considerable spatial changes and has large temporal variability of various timescales related to the mechanisms of creation, decay and transport of space ionospheric plasma. Many techniques for modelling electron density profiles through entire ionosphere have been developed in order to solve the "age-old problem" of ionospheric physics which has not yet been fully solved. A new way to address this problem is by applying artificial intelligence methodologies to current large amounts of solar-terrestrial and ionospheric data. It is the aim of this paper to show by the most recent examples that modern development of numerical models for ionospheric monthly median long-term prediction and daily hourly short-term forecasting may proceed successfully applying the artificial neural networks. The performance of these techniques is illustrated with different artificial neural networks developed to model and predict the temporal and spatial variations of ionospheric critical frequency, f0F2 and Total Electron Content (TEC). Comparisons between results obtained by the proposed approaches and measured f0F2 and TEC data provide prospects for future applications of the artificial neural networks in ionospheric studies.JCR Journalope
Advances in regional ionospheric mapping over europe
No full textOver the past several years significant advances have been made in all areas of ionospheric modelling and mapping studies. Ionospheric models and maps of varying complexity have been formulated from analytic and simple numerical models that are user friendly" calculations to complete general circulation models that require hours on today’s supercomputers. All have their place and are used in different applications. This review describes progress in regional ionospheric mapping over Europe in the frame of the COST 238 and 251 projects.JCR Journalope
Regional GPS receiver networks for monitoring local mid-latitude total electron content
No full textTwo regional GPS receiver networks from the Ordnance Survey U.K.(OS)and the Italian Space Agency (ASI) have been used for monitoring mid-latitude Total Electron Content (TEC)during quiet and disturbed ionospheric conditions in the current solar cycle.A few quiet and disturbed days in March and April 2002 were examined. These showed how the temporal and spatial patterns of changes develop and how they are related to solar and geomagnetic activity for parameter descriptive of plasmaspheric-ionospheric ionisation.Use is then made of computer contouring techniques to produce snapshots of daily maps of TEC for these different regional areas.PublishedJCR Journalope
Mid-latitude ionosphere during two great geomagnetic storms
No full textThe ionospheric disturbances observed at many European ionosonde stations in association with the severe geomagnetic storms occurring on 19-20 December 1980 and 11-12 April 1981 were investigated by using the available ionospheric and geomagnetic data. During these storms the ionospheric F region underwent major changes at all mid-latitudes. However, the variations from storm to storm were much larger at lower mid-latitudes. These results support the view that even in assessing the response of the mid-latitude ionosphere to severe geomagnetic storms it is necessary to distinguish carefully between global, regional and local behaviour.JCR Journalope
COST 271 Action - Effects of the upper atmosphere on terrestrial and Earth-space communications: introduction
No full textThe COST 271 Action («Effects of the Upper Atmosphere on Terrestrial and Earth-space Communications
») within the European ionospheric community has the objectives, embodied in the
Memorandum of Understanding (MoU): to study the influence of upper atmospheric conditions on
terrestrial and Earth-space communications, to develop methods and techniques to improve ionospheric
models over Europe for telecommunication and navigation applications and to transfer the results
to the appropriate Radiocommunication Study Groups of the International Telecommunication
Union (ITU-R) and other national and international organizations dealing with the modern communication
systems. This introductory paper summarises briefly the background and historical context
of COST 271 and outlines the main objectives, working methods and structure. It also lists the participating
countries and institutions, the Management Committee (MC) Meetings, Workshops and
Short-term Scientific Missions. In addition, the paper discusses the dissemination of the results and
the collaboration among the participating institutions and researchers, before outlining the content of
the Final Report.PublishedJCR Journalope
Interfacing between regional and global, electron density height profile
No full textA first analysis of the possibility of interfacing regional and global electron density height profile models, over a buffer zone, was performed considering the results obtained using different models such as IRI 90 (Bilitza, 1990), DGR (Di Giovanni et al., 1992) and RAL MPQ (Dick and Bradley, 1992). The differences ?N ?cm–3 of electron density as a function of altitude between different models were calculated using monthly median experimental data measured at Rome station and values predicted by URSI, STRM (Zolesi et al., 1993) and EOF (Singer and Dvinskikh, 1991) mapping models for the same point. Composite ionograms are used to roughly evaluate the performances of the three models considered.JCR Journalope
Science Rational for MIERS/IRI Collaboration
No full textIn this paper, we will shortly highlight some of the aspects that COST Action 296 on Mitigation of Ionospheric Effects on Radio Systems (MIERS) and International Reference Ionosphere (IRI) have in common in an attempt to define science rationale for collaboration between these two international projects.Published1621-16232A. Fisica dell'alta atmosferaJCR Journalope
The COST 271 Action: conclusions and the way ahead
No full textA brief summary is given of the major achievements of the COST 271 Action. New challenges have been identified that open the way for a proposal, which is outlined, for a follow-on to the COST 271 Action within the COST Telecommunications, Information Science and Technology
framework.PublishedJCR Journalope
Regional GPS receiver networks for monitoring local mid-latitude total electron content
Full text linkTwo regional GPS receiver networks from the Ordnance Survey U.K.(OS)and the Italian Space Agency (ASI) have been used for monitoring mid-latitude Total Electron Content (TEC)during quiet and disturbed ionospheric conditions in the current solar cycle.A few quiet and disturbed days in March and April 2002 were examined. These showed how the temporal and spatial patterns of changes develop and how they are related to solar and geomagnetic activity for parameter descriptive of plasmaspheric-ionospheric ionisation.Use is then made of computer contouring techniques to produce snapshots of daily maps of TEC for these different regional areas
Proposed terminology for the classification and parameters for the quantification of variability in ionosphere morphology
No full textMuch uncertainty currently exists in the use by different workers of the term variability in describing the results of statistical analyses applied to ionospheric measurement data sets and in their relationships with various existing or new ionospheric models. Often it is not clear whether data for different time periods or different geographical areas, and if so which, are being used to formulate results. Terms are presented in the Annex which it is suggested should be used, at least once in every publication addressing this topic, to describe unambiguously what is talked about. The background to the proposed terminology is discussed. Options for variability parameters are also addressed.PublishedJCR Journalope
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