147 research outputs found
From COST 238 To COST 296: Four European COST Actions On Ionospheric Physics And Radio Propagation
COST (Co-operation in the field of Scientific and Technical Research) is an important instrument supporting co-operation among scientists and researchers across Europe now joining 35 member countries. Scientific
projects in the COST framework are called COST Actions and have the objectives embodied in their respective Memorandum of Understanding (MoU). The main objectives of the COST Actions within the European ionospheric and radio propagation community have been: to study the influence of upper atmospheric conditions on terrestrial and Earthspace communications, to develop methods and techniques to improve existing and generate new ionospheric and propagation models over Europe for telecommunication and navigation applications and to transfer the results to the appropriate national and international organizations, institutions and industry dealing with the modern communication systems. This paper summarises in brief the background and historical context of four ionospheric COST Actions and
outlines their main objectives and results. In addition, the paper discusses the dissemination of the results and the
collaboration among the participating institutions and researchers
The COST 271 Action: conclusions and the way ahead
A 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
COST 271 Action - Effects of the upper atmosphere on terrestrial and Earth-space communications: introduction
The 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
The European COST (Co-operation in the field of Scientific and Technical Research) Actions: an important chance to cooperate and to grow for all the international ionospheric community
The current COST (Co-operation in the field of Scientific and Technical Research) Action 296 on Mitigation of Ionospheric Effects on Radio Systems, along with previous COST238 (Prediction and Retrospective Ionospheric Modelling over Europe), COST251 (Improved Quality of Service in Ionospheric Telecommunication Systems Planning and Operation) and COST271 (Effects of the Upper Atmosphere on Terrestrial and Earth-Space Communications) Actions have addressed
investigations of the different effects of the ionosphere on terrestrial telecommunication systems and on Earth-space systems. Throughout their lifetime of 20 years, these COST actions have achieved a
great deal in long-term archiving of synoptic soundings of the state of the ionosphere, in enhancing understanding of the morphology of the ionosphere and its dependence on space weather and in producing ionosphere-plasmasphere as well as propagation models for terrestrial radio services available to variety of radio users. Besides the formal contributions to ITU-R and the contributions to international organisations such as URSI, COSPAR, EGU and ESA, these COST Actions have provided a forum for the establishment of collaborative European initiatives, a centre of expertise
and excellence in ionosphere knowledge when none other equivalent in Europe or elsewhere exists. In this paper, we review the main achievements of the COST 238, 251 and 271 actions as developed in the past studies
Regional GPS receiver networks for monitoring local mid-latitude total electron content
Two 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
A dynamic system to forecast ionospheric storm disturbances based on solar wind conditions
For the reliable performance of technologically advanced radio communications systems under geomagnetically
disturbed conditions, the forecast and modelling of the ionospheric response during storms is a high priority. The
ionospheric storm forecasting models that are currently in operation have shown a high degree of reliability during
quiet conditions, but they have proved inadequate during storm events. To improve their prediction accuracy, we
have to take advantage of the deeper understanding in ionospheric storm dynamics that is currently available, indicating
a correlation between the Interplanetary Magnetic Field (IMF) disturbances and the qualitative signature
of ionospheric storm disturbances at middle latitude stations. In this paper we analyse observations of the foF2 critical
frequency parameter from one mid-latitude European ionospheric station (Chilton) in conjunction with observations
of IMF parameters (total magnitude, Bt and Bz-IMF component) from the ACE spacecraft mission for eight
storm events. The determination of the time delay in the ionospheric response to the interplanetary medium disturbances
leads to significant results concerning the forecast of the ionospheric storms onset and their development
during the first 24 h. In this way the real-time ACE observations of the solar wind parameters may be used in the
development of a real-time dynamic ionospheric storm model with adequate accuracy
Proposed terminology for the classification and parameters for the quantification of variability in ionosphere morphology
Much 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
COST 296 MIERS: Mitigation of Ionospheric Effects on Radio Systems
The COST 296 Action MIERS (Mitigation of Ionospheric Effects on Radio Systems) within the ionospheric community has the objectives, embodied in the Memorandum of Understanding (MoU), to develop an increased
knowledge of the effects imposed by the ionosphere on practical radio systems, and the development and implementation
of techniques to mitigate the deleterious effects of the ionosphere on such systems. This introductory paper summarizes briefly the background and historical context of COST 296 and outlines the main objectives,
working methods and structure. It also lists the participating countries and institutions, the Management Committee (MC) Meetings, the Workshops, Short-term Scientific Missions. In addition, the paper discusses the dissemination activities and the collaboration among the participating institutions and researchers, before outlining the content of the Final Report
COST 296 MIERS: conclusion
The need for more reliable and efficient
communications services, especially those involving ionospheric HF communications and
navigational systems, imposes increasing demand for a better knowledge of the effects imposed by the Earth’s upper atmosphere and
ways to mitigate disturbing effects. Temporal
and spatial changes in the upper atmosphere act to limit and degrade the performance of terrestrial and Earth-space radio systems in many different ways and this is why mitigation activities must involve several topics like ionospheric monitoring and modeling, development of new hardware for communication systems and new propagation simulator, measurements and modeling
of ionospheric Total Electron Content
(TEC) and ionospheric scintillations, using in particular the Global Positioning System
(GPS). The European ionospheric community
has long been aware that cooperation research
on an international basis is essential to deal with such complex issues. In particular, international cooperation is required for the collection of data, in both the real-time and in retrospective
modes, the development and verification of
new methods to improve the performance of
both operational and future terrestrial and
Earth-space communication systems and the
exchange of expertise on space plasma effects
on Global Navigation Satellite Systems
(GNSS).
In this context the COST 296 Action
MIERS on the «Mitigation of Ionospheric Effects on Radio Systems» has made a significant impact in a number of areas
Ionospheric storm forecasting technique by artificial neural network
In this work we further refine and improve the neural network based ionospheric characteristic's foF2 predictor,
which is actually a neural network autoregressive model with additional input signals (NNARX). Our analysis
is focused on choice of X parts of NNARX model in order to capture middle and long term dependencies. Daily
distribution of prediction error suggests need for structural changes of the neural network model, as well as
adaptation of running average lengths used for determination of X inputs. Generalisation properties of proposed
neural predictor are improved by carefully designed pruning procedure with additional regularisation term in
criterion function. Some results from the NNARX model are presented to illustrate the feasibility of using such
a model as ionospheric storm forecasting technique
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