Impact of COST 271

This article discusses the significance of the achievements of the COST 271 Action on science and technology for space weather and telecommunications in Europe and the world. The Action's work has impacted national and international projects and the decision processes. The key words encompassed in the title of COST 271 are «space weather». But as the reader of this Final Report will appreciate, many more topics were addressed during the Action by the large team of workers from a wide range of countries and organisations than this wording would suggest. Relevant to the performance of telecommunication systems that rely on the presence of the ionosphere for propagation support, or that are affected by transmission through it, there have been investigations among other items of solar and magnetosphere disturbances on the ionosphere, satellite and ground-based measurements of the ionosphere, assembly of near-real-time databases of ionosphere information on the Web, studies of planetary and gravity waves in the ionosphere, ionosphere modelling, mapping and forecasting, long-term changes, ray-path deviations in the presence of irregularities, channel-scattering functions, and scintillations on Earth-space paths. The impact of all this work on the outside communities can be considered within three broad headings as follows

Using scale heights derived from bottomside ionograms for modelling the IRI topside profile

Groundbased ionograms measure the Chapman scale height <i>H_T</i> at the F2-layer peak that is used to construct the topside profile. After a brief review of the topside model extrapolation technique, comparisons are presented between the modeled profiles with incoherent scatter radar and satellite measurements for the mid latitude and equatorial ionosphere. The total electron content TEC, derived from measurements on satellite beacon signals, is compared with the height-integrated profiles ITEC from the ionograms. Good agreement is found with the ISR profiles and with results using the low altitude TOPEX satellite. The TEC values derived from GPS signal analysis are systematically larger than ITEC. It is suggested to use <i>H_T</i> , routinely measured by a large number of Digisondes around the globe, for the construction of the IRI topside electron density profile

Concurrent study of bottomside spread F and plasma bubble events in the equatorial ionosphere during solar maximum using digisonde and ROCSAT-1

Data from the Jicamarca digisonde and the ROCSAT-1 satellite are employed to study the equatorial ionosphere on the west side of South America during April 1999-March 2000 for the concurrent bottomside spread F (BSSF) and plasma bubble events. This study, using digisonde and ROCSAT-1 concurrently, is the first attempt to investigate the equatorial spread F. Results show that BSSF and plasma bubble observations appear frequently respectively in the summer (January, February, November, and December) and in the equinoctial (March, April, September, and October) months, respectively, but are both rarely observed in the winter (May-August) months. The upward drift velocity during the concurrent BSSF and bubble observations has been determined to study the driving mechanism. This analysis shows that large vertical drift velocities favor BSSF and bubble formations in the equinoctial and summer months. Conversely, the smaller upward velocities during the winter months cause fewer BSSF and bubble occurrences. For the geomagnetic effect, the BSSF/bubble occurrence decreases with an increasing &lt;i&gt;K&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt; value in the equinoctial months, but no such correlation is found for the summer and winter months. Moreover, the anti-correlations between &lt;i&gt;K&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt; and d&lt;i&gt;h&apos;F&lt;/i&gt;/dt are apparent in the equinoctial months, but not in the summer and winter months. These results indicate that in the equinoctial months the BSSF/bubble generations and the pre-reversal drift velocity can be suppressed by geomagnetic activity, because the disturbance dynamo effects could have decreased the eastward electric field near sunset. However, BSSF and bubble occurrences may not be suppressed by the geomagnetic activity in the summer and winter months

Electon density profiles of the topside ionosphere

The existing uncertainties about the electron density profiles in the topside ionosphere, i.e., in the height region from h m F 2 to ~ 2000 km, require the search for new data sources. The ISIS and Alouette topside sounder satellites from the sixties to the eighties recorded millions of ionograms but most were not analyzed in terms of electron density profiles. In recent years an effort started to digitize the analog recordings to prepare the ionograms for computerized analysis. As of November 2001 about 350 000 ionograms have been digitized from the original 7-track analog tapes. These data are available in binary and CDF format from the anonymous ftp site of the National Space Science Data Center. A search site and browse capabilities on CDAWeb assist the scientific usage of these data. All information and access links can be found at http://nssdc.gsfc.nasa.gov/space/isis/isis-status. html. This paper describes the ISIS data restoration effort and shows how the digital ionograms are automatically processed into electron density profiles from satellite orbit altitude (1400 km for ISIS-2) down to the F peak. Because of the large volume of data an automated processing algorithm is imperative. The TOPside Ionogram Scaler with True height algorithm TOPIST software developed for this task is successfully scaling ~ 70% of the ionograms. An «editing process» is available to manually scale the more difficult ionograms. The automated processing of the digitized ISIS ionograms is now underway, producing a much-needed database of topside electron density profiles for ionospheric modeling covering more than one solar cycle

Short-term relationship between solar irradiances and equatorial peak electron densities

[1] The short-term relationship of the equatorial peak electron density and the solar short-wavelength irradiance is examined using foF2 observations from Jicamarca, Peru and recent solar irradiance measurements from satellites. Solar soft X-ray measurements from both the Student Nitric Oxide Explorer (SNOE) ( 1998 - 2000) and Thermosphere Ionosphere Mesosphere Energetics Dynamics ( TIMED) ( 2002 - 2004) satellites as well as extreme ultraviolet (EUV) measurements from the TIMED satellite are used. Soft X-rays show similar or higher correlation with foF2 at short timescales ( 27 days or less) than EUV does, although the EUV correlation is higher for longer periods. For the short-term variations, both SNOE and TIMED observations have a higher correlation in the morning ( similar to 0.46) than in the afternoon ( similar to 0.1). In the afternoon, SNOE observations have a higher correlation ( similar to 0.2) with foF2 than the TIMED observations ( similar to 0.1 correlation), which may be due to differences in the solar cycle. At morning times, foF2 has a similar to 27-day variation, consistent with the solar rotation rate. After noon, but not in the morning, a similar to 13.5-day variation consistently appears in foF2. This similar to 13.5-day variation is attributed to geomagnetic influences

Simple Lattice-Models of Ion Conduction: Counter Ion Model vs. Random Energy Model

The role of Coulomb interaction between the mobile particles in ionic conductors is still under debate. To clarify this aspect we perform Monte Carlo simulations on two simple lattice models (Counter Ion Model and Random Energy Model) which contain Coulomb interaction between the positively charged mobile particles, moving on a static disordered energy landscape. We find that the nature of static disorder plays an important role if one wishes to explore the impact of Coulomb interaction on the microscopic dynamics. This Coulomb type interaction impedes the dynamics in the Random Energy Model, but enhances dynamics in the Counter Ion Model in the relevant parameter range.Comment: To be published in Phys. Rev.

Backward correlations and dynamic heterogeneities: a computer study of ion dynamics

We analyse the correlated back and forth dynamics and dynamic heterogeneities, i.e. the presence of fast and slow ions, for a lithium metasilicate system via computer simulations. For this purpose we define, in analogy to previous work in the field of glass transition, appropriate three-time correlation functions. They contain information about the dynamics during two successive time intervals. First we apply them to simple model systems in order to clarify their information content. Afterwards we use this formalism to analyse the lithium trajectories. A strong back-dragging effect is observed, which also fulfills the time-temperature superposition principle. Furthermore, it turns out that the back-dragging effect is long-ranged and exceeds the nearest neighbor position. In contrast, the strength of the dynamic heterogeneities does not fulfill the time-temperature superposition principle. The lower the temperature, the stronger the mobility difference between fast and slow ions. The results are then compared with the simple model systems considered here as well as with some lattice models of ion dynamics.Comment: 12 pages, 10 figure

COST 296 scientific results designed for operational use

The main objective of the COST 296 Action «Mitigation of Ionospheric Effects on Radio Systems» is the establishment/ improvement of ionospheric services by coordinating the development of specific algorithms, models, and tools capable of operating in a near-real-time mode. Key elements of these activities are contributions related to monitoring, modelling, and imaging of customer-relevant ionospheric quantities. COST stimulates, coordinates, and supports Europe’s goals of development and global cooperation by providing high quality information and knowledge of ionospheric and plasmaspheric conditions enabling high quality and reliable operation of radio systems. It also provides a platform for sharing such tools as algorithms or models, and for the joint development of advanced technologies. It takes advantage of many national and European service initiatives, for example DIAS (http://dias.space.noa.gr), SWACI (http://w3swaci.dlr.de), ESWUA (http://www.eswua.ingv.it/ingv), RWC-Warsaw (http://www.cbk.waw.pl/rwc), the COST Prompt Ionospheric Database http://www.wdc.rl.ac.uk/cgibin/ digisondes/cost_database.pl, http://www.izmiran.ru/services, and others. Existing national capabilities are taken into account to develop synergies and avoid duplication. The enhancement of environment monitoring networks and associated instrumentation yields mutual advantages for European and regional services specialized for local user needs. It structurally increases the integration of limited-area services, and generates a platform employing the same approach to each task differing mostly in input and output data. In doing so it also provides a complementary description of the environmental state within issued information, as well as providing a platform for interaction among local end users, who define what kind of information they need, for system providers, who finalize the tools necessary to obtain required information, and for local service providers, who do the actual processing of data, tailoring it to specific users’ needs. Such an initiative creates a unique opportunity for small national services to consolidate their product design so that is no longer limited to their own activity, but can serve the wider European services. The development and improvement of techniques for mitigating ionospheric effects on radio systems by the COST 296 Action prepared those services that implemented the new design techniques for the newly announced EU and ESA policy-Space Situation Awareness (SSA). COST 296 developments applied to nowcasting and forecasting services are an essential input to the Operational SSA Ionosphere