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The European Space Agency's Space Situational Awareness (SSA) Space Weather (SWE) Portal provides users with access to space weather services built upon a large variety of products, tools and alerting together with expert user support and guidance. Understanding the performance of the different service elements under a range of space weather conditions is essential to providing reliable information to end users. In the frame of SSA Period 3 activities, an initial set of 'Guidelines for common validation in the SSA SWE Network' have been developed by a working group consisting of representatives of the SWE Expert Service Centres with the aim to provide a common basis for future validation campaigns. This poster presents preliminary results from application of the suggested techniques and metrics on a sample of products available via the SWE Portal for the period of heightened space weather activity observed during September 2017. The cross-domain project demonstrates the applicability of the suggested validation techniques, whilst also identifying any ambiguities in the terminology used within the guidelines themselves. As a result of these tests, information on the performance of the analysed products during this heightened period of space weather is also provided.

Travelling Ionospheric Disturbances (TIDs) are propagating wavelike disturbances in the ionosphere electron density, which are signatures of atmospheric gravity waves that are active in the thermosphere. These waves are either generated in the thermosphere through intensive energy input from the solar wind or the solar terminator, or they are generated in the lower and middle atmosphere and propagate upwards into the thermosphere. Prominent sources of gravity wave which reach the thermosphere are earthquakes and tropical thunderstorms. Usually, gravity waves originating in the atmosphere below have smaller scales than those originating in the thermosphere. The corresponding TIDs are referred to as Medium Scale TIDs and Large Scale TIDs (LSTIDs). The EU Horizon 2020 project "Warning and Mitigation Technologies for Travelling Ionospheric Disturbances Effects - TechTIDE" implements a few different techniques for the detection of MS- and LSTIDs in the different layers of the ionosphere. They are based on different instruments and algorithms and deliver a comprehensive view on the TID activity in Europe and South Africa. The results of the different approaches will be presented for a case study for the September 2017 Space Weather event.

Because the propagation of radio signals is sensitive to the electron density in the ionosphere, ionospheric perturbations are of great interest for applications using radio systems (e.g. GNSS and HF communication). Especially high latitudes are impacted by manifold ionospheric perturbations, which can have different characteristics. Their spatial range can vary between global and very local effects (e.g. a few hundreds of km range) and their temporal range varies between seconds and days. All these perturbations have different physical background and different impact on applications. Therefore, many ionosphere perturbation indices characterizing ionospheric perturbations have been introduced in the past (e.g. ROTI, S4, \sigma_\phi, AATR, Reff, W-index, SISTED, SOLERA, DIXSG, IBI, Dfu/Dfl, etc.). This presentation provides a summary overview on a subset of 19 ionospheric indices that were developed and/or applied in Europe. It points out, which indices are applicable for different use cases in science and industry in high latitudes and guides users to find the appropriate index for their purposes.

ESPAS, the “near-Earth space data infrastructure for e-science” is a data e-infrastructure facilitating discovery and access to observations, ground-based and space borne, and to model predictions of the near-Earth space environment, a region extending from the Earth's atmosphere up to the outer radiation belts. ESPAS provides access to metadata and/or data from an extended network of data providers distributed globally. The interoperability of the heterogeneous data collections is achieved with the adoption and adaption of the ESPAS data model which is built entirely on ISO 19100 series geographic information standards. The ESPAS data portal manages a vocabulary of space physics keywords that can be used to narrow down data searches to observations of specific physical content. Such content-targeted search is an ESPAS innovation provided in addition to the commonly practiced data selection by time, location, and instrument. The article presents an overview of the architectural design of the ESPAS system, of its data model and ontology, and of interoperable services that allow the discovery, access and download of registered data. Emphasis is given to the standardization, and expandability concepts which represent also the main elements that support the building of long-term sustainability activities of the ESPAS e-infrastructure. © 2016 COSPAR

Analysis of the time series into trigonometric series allows the investigation of cosmic-ray (CR) intensity variations in a range of periodicities from a few days to 1 year. By this technique the amplitude and the phase of all observed fluctuations can be given. For this purpose, daily CR intensity values recorded at Climax Neutron Monitor station for the time intervals 1979-1982 and 1989-1991, which correspond to the epochs of maximum activity for solar cycles 21 and 22, respectively, have been studied. The data analysis revealed the occurrence of new periodicities, common or not, in the two solar maxima. A search of our results was done by a power spectral analysis determining independently possible systematic periodic or quasi-periodic variations. Based on the fact that during these maxima the CR intensity tracks the solar flare index better than the sunspot number, the same analysis was performed on these data, which are equivalent to the total energy emitted by the solar flares. Both analyses result in periodicities with different probability of occurrence in different epochs. Occurrence at peaks of 70, 56, 35, 27, 21 and 14- days were observed in all time series, while the periods of 140-154 and 105 days are reported only in the 21st solar maximum and are of particular importance. All of the short-term periods except of those at 27 and 154-days are recorded for first time in CR data, but they had already been observed in the solar activity parameters. Moreover, each parameter studied here has a very different power spectrum distribution in periods larger than 154 days. The possible origin of the observed variations in terms of the CR interaction in the upper atmosphere and the solar cavity dynamics is also discussed here. © 2003 Elsevier Ltd. All rights reserved.

A study of the cosmic-ray intensity power spectrum using the Climax Neutron Monitor data in the frequency range from 10-9 Hz to 10-7 Hz (which corresponds to periodicities from 11 years to a few months) during the period 1953-1996, was carried out by means of the successive approximations method of analysis and was compared against the power spectrum and the maximum entropy methods. The contributions of the time evolution of several peaks to the global one were obtained. Except for the well-known 11-year and the 1-year variations, peaks at 7.7, 5.5, 2 and 1.7 years are found. Several peaks with periods less than 10 months have appeared in our analysis, while the occurrence of 5.1 months is obtained in all the examined solar cycles with a strong signature in cycle 21. Transitions of these quasiperiodicities are seen in power spectra plots. Some of them can be attributed to the modulation of the cosmic ray intensity by solar activity. Others are sporadic and have been previously attributed to the interplanetary magnetic field. The results obtained support once again the argument regarding the difference in the solar activity between odd and even solar cycles.

Magnetospheric energetics during substorm events is studied in this paper. Three events were selected, a weak substorm, a large isolated one and finally a prolonged period of substorm activity with multiple intensifications. It is assumed that the energy, that entered the magnetosphere due to electromagnetic coupling with the solar wind, is described by the epsilon parameter, proposed by Perreault and Akasofu (1978). High resolution, magnetic field and plasma data from the MGF and LEP experiments on board GEOTAIL were analyzed to determine the timing of plasmoid release, its dimensions, its convection velocity and finally the energy carried by each plasmoid. Plasmoids were defined as structures with rotating magnetic fields and enhanced total pressure. Tailward plasmoid bulk speed in the distant tail varied from 350 to 750 km/s. Their dimensions in XGSM direction was found to be from 4.5 to 28Re, and their duration did not exceed 5min. The average energy carried by each plasmoid in the distant tail was estimated to be equal to (2.4±1.0)×1014J. The thermal energy flux dominates when the plasmoid structure is a closed loop. In cases of flux rope plasmoids the kinetic energy is comparable to or even greater than the thermal energy flux. The study of the overall magnetospheric energetics yielded the result that the input solar wind energy, estimated by the integral of the epsilon parameter over the lifetime of a substorm, represents the energy stored in the magnetotail and the convective dissipation in the ionosphere as well. The energy required for the plasmoid release is thought to be provided by the night side reconnection in the near-Earth neutral line location. Finally, it was found that 20% of the total input solar wind energy is dissipated in the auroral ionosphere. © 2001 Elsevier Science Ltd.

The use of monthly median values to determine the normal level of the undisturbed F2 layer, leads often to inconsistent results regarding the type of ionospheric disturbance and quietness as well. Recently Belehaki et al. (2000) proposed an hourly local ionospheric index fnF2 to define the normal level of the F2 layer at middle latitudes. In this paper we apply the fnF2 index to observations from a high latitude station, where geomagnetic activity strongly influence the temporal and spatial behaviour of the ionospheric layers, for investigating and testing the usefulness of the fnF2 index on a planetary scale. From the analysis that follows, it was revealed that during intervals of low magnetospheric activity, fnF2 index shows a very good fit to the observed foF2 parameter, comparing to the monthly median foF2 behaviour. On the other hand, enhanced magnetospheric activity does not affect the fnF2 index, which daily variation is a function of the sunspot number itself. In summary, the fnF2 index can be used as a measure of the undisturbed F2 layer at middle and high latitudes as well, caution though is needed in the definition of the quiet magnetospheric intervals, which for the needs of this work it was approached as a function of the aa-index for middle latitudes, whereas the AE-index was used for auroral latitudes. © 2001 Elsevier Science Ltd. All rights reserved.

The ionospheric response to enhanced geomagnetic activity was studied in terms of two ionospheric parameters, FoF2 and h'F2, aiming the investigation of the middle latitude positive and negative ionospheric storm effects characteristics. Simultaneous observations from a chain of several middle latitude stations distributed in longitude around the earth during two intense geomagnetic storms (Dst < -100 nT), were analyzed in this work. The correlation results between the foF2 and h'F2 disturbances and the Dst geomagnetic index verified that the morphology of middle latitude ionospheric disturbances in response to geomagnetic storms shows a great degree of variability and a strong dependence on local time observation. Negative deviations constitute the typical ionospheric response. In general it is reported that the F2 layer virtual height h'F2, which is observed only during daytime in conjunction with F1 layer presence, shows clear response to magnetic storm activity. On the other hand, positive ionospheric disturbances are accompanied by weak height enhancements. Real observations were also compared to the thermospheric-ionospheric view associated with positive and negative storm effects proposed by Prolss (1993). This test clearly demonstrates that such a model can capture most of the basic aspects of ionospheric storms, taking into consideration that any new burst of activity is associated to a new disturbance zone, resulting to the formation of a large zone of disturbance that covers the post-midnight and the forenoon sector as well. This mechanism may be the cause of long lasting negative storm effects observed as the typical ionospheric response to geomagnetic storm activity. © 2001 Elsevier Science Ltd. All rights reserved.

The morphology of middle latitude ionospheric disturbances in response to geomagnetic storms has been investigated to determine the phenomenological differences between positive and negative ionospheric storm effects, using foF2 observations from azimuthal chain of stations. To better organize the disturbance signatures, two ionospheric indices were introduced to describe the maximum positive (Dfu-index) and negative (Dfl-index) deviation observed during an ionospheric storm. A systematic appearance of nighttime positive effects was determined with a 24-hour recurrence. The thermospheric-ionospheric view associated with positive and negative storm effects proposed by Prolss (1993) was extended to encompass our observations. This test clearly demonstrates that such a model can capture most of the basic aspects of ionospheric storms, nevertheless the prominent feature of large nighttime enhancements in the ionization density have yet to be explained.

An analysis of 373 well-defined high-speed solar-wind streams observed at 1 AU during the years 1985-1996 is outlined. The distribution of the occurrence of these streams as a function of Bartels rotation days using the dominant polarity of the interplanetary magnetic field (IMF) associated with the referred fast streams shows that a four-sector pattern for the positive IMF polarity and a two-sector pattern for the negative IMF polarity are the dominant features in the investigated period. The high-speed streams seem to occur at preferred Bartels days: positive polarity streams are most frequent near Bartels days 5 and 18, while negative polarity streams are most frequent in days 14 and 23. Moreover, the corotating streams with positive IMF polarity prefer to occur in days 5 and 18 of the Bartels rotation period, whereas flare-generated streams with negative IMF polarity occur in days 14 and 23. The observed distribution of Bartels days is probably related to the distribution of the solar sources of high-speed solar wind streams as the solar wind carries with it the photospheric magnetic polarity of the solar source region. In addition, the distribution of the streams reveals a similar behaviour during the ascending and the declining phase of the last solar cycle (22nd) in contrast to the previous one where it has an opposite appearance. Determined differences in the characteristics of the sector structured IMF associated with the fast streams of the last cycle with the previous one (21st) and some similarities with the alternate solar cycle (20th) seem to be attributed to the 22-year magnetic cycle and to the polarity reversals of the polar magnetic field of the Sun. As the magnetic sectors are due to multiple crossings of the solar equatorial plane by a large-scale, warped heliospheric current sheet, it is suggested that the two-sector pattern arises from a tilted solar magnetic dipole component and the more commonly observed four-sector pattern from a quadrupole component of the solar interplanetary magnetic field.

In this work we examine simultaneous observations from the two geosynchronous satellites GOES-5 and GOES-6 located at 282°E and 265°E respectively, and from middle and low latitude ground observatories located within 250°E and 294°E geographic longitude, during isolated substorms of moderate activity. The spatial distribution of our observation points allows us to make a detailed study of the azimuthal expansion of the substorm current wedge. The data analysis shows evidence that the substorm initiation and development mechanism include the cross-tail current diversion/disruption, the substorm current wedge formation and the azimuthal expansion of the inner plasma sheet. The triggering mechanism is initially confined in a longitudinally narrow sector, estimated to be less than 15° and located very close to local midnight to the east or to the west. The current disruption region expands both eastward and westward in the magnetotail, so that the location of major field-aligned currents flowing into the ionosphere shifts successively eastward, and the location of the currents flowing out of the ionosphere shifts successively westward. Evidence was found that the perturbation travels toward the west with velocities greater than those expanding the wedge eastward. The drastic decrease of the velocity with the azimuthal distance from the location of the disturbance initiation, i.e., the onset sector, indicates that the energy release is a very localized phenomenon. Finally, the transient D perturbation observed by the geosynchronous satellites suggests that the field-aligned currents forming the wedge have a longitudunally limited extent.

Monthly cosmic-ray data from Inuvik (0.16 GV) and Climax (2.96 GV) Neutron Monitor stations has been studied with the aid of solar activity parameters for the time period 1947-1995. Systematic differences in the overall shape of successive 11-year modulation cycles and similarities in the alternate 11-year cycles seem to be related to the polarity reversals of the polar magnetic field of the Sun. This suggests a possible effectiveness of the Hale cycle during even and odd solar activity cycles. Our results can be understood in terms of open and closed models of the heliosphere. Positive north pole of the Sun leads to open heliosphere where particles reach the Earth more easily when their access route is by the heliospheric polar regions (even cycles) than when they gain access along the current sheet (odd cycles). In this case as the route of access becomes longer due to the waviness of the neutral sheet, the hysteresis effect of cosmic-rays is also longer. This interpretation is explained in terms of different contributions of convection, diffusion and drift mechanisms to the whole modulation process influencing cosmic-ray transport in the heliosphere.