COST 271 Action Effects of the Upper Atmosphere on Terrestrial and Earth Space Communications - EACOS/ PROGRESS REPORT Period: from May 2001 to April 2002 Thessaloniki June 2002

COST Action 271 : Effects of the Upper Atmosphere on Terrestrial and Earth-Space Communications ( EACOS ) TC Recommendation: 29 October 1999 CSO Approval: 10 December 1999 First MC meeting: 9 October 2000 Start date: 16 August 2000 Duration: 48 months End date: 15 August 2004

COST Action 271 : Effects of the Upper Atmosphere on Terrestrial and Earth-Space Communications ( EACOS ) Number of signatories: 16 Signatories and date of signature Austria 7 June 2000 Greece 31 May 2000 Poland 10 May 2000 Hungary 23 May 2000 Bulgaria 16 August 2000 Italy 3 July 2000 Czech Rep. 26 June 2000 Spain 10 May 2000 Portugal 26 October 2000 Latvia 9 June 2000 Finland 6 September 2000 Turkey 26 May 2000 France 10 May 2000 United Kingdom 29 June 2000 Germany 17 May 2000 Yugoslavia 21 Jan ( intention)

Objectives The main objectives of the COST 271 Action are: to perform studies to influence the technical development and the implementation of new communication services, particularly for the GNSS and other advanced Earth-space and satellite to satellite applications, to develop methods and algorithms to predict and to minimise the effects of ionospheric perturbations and variations on communications and to ensure that the best models over Europe are made available to the ITU-R,

to collect additional and new ionospheric and plasmaspheric data for now-casting and forecasting purposes, to stimulate further co-operation in the domain of ionospheric and plasmaspheric prediction and forecasting for terrestrial and Earth-space communications, including interactive repercussions on the corresponding standards in this field, taking into account the present and future needs of users.

TECHNICAL DESCRIPTION AND IMPLEMENTATION Working Group 1: Impact of variability of space environment on communications 1. Impact of space weather on communication. 2. Real-time satellite and terrestrial measurements for now- casting, forecasting and warning purposes. 3. Improved robustness performance of prediction. 4. Long-term trends in the ionosphere and upper atmosphere parameters. 5. Upper atmosphere parameters monitoring for now-casting and forecasting purposes

Working Group 2: Assessment of space plasma effects for satellites applications 1.Plasma effects on GNSS applications. 2.Assessment of plasma propagation errors in navigation systems and merits and shortcomings of novel data sources. 3.Investigation of extremes of ionization.

Working Group 3: Ionospheric effects on terrestrial communications 1. Effects of large-scale fluctuations on terrestrial communications. 2. Effects of small-scale ionospheric irregularities, interference and noise on terrestrial communication, including remote sensing, radio localization and radar. 3. Mid-latitude ionospheric features in radio propagation models. 4. Development of methods and algorithms to minimize the effects of small and large scale fluctuations on terrestrial communications.

Working Group 4 : Space plasma effects on Earth-space and satellite to satellite communications. Effects of space plasma variability and irregularities on Earth-space and satellite to satellite communication channels. Development of algorithms and software to treat with disturbances in Earth-space and satellite to satellite communications. Application of theoretical considerations to the study of space plasma effects. Effects of the electron density vertical and horizontal gradients on the satellite-satellite communications. D

MAIN RESULTS DURING THE PERIOD MAY 2001 TO APRIL 2002 Working Group 1: Impact of variability of space environment on communications Five active Working packages report their progress during the last year. The first one on Impact of space weather on communication studied propagation phenomena, which are under some circumstances related to the space weather events.

Interactive foF2, MUF(3000)F2, TEC maps across Europe foF2 and TEC plots for each European observational location and associated archive database Ionospheric long-term prediction and short-term forecasting computational tools WG1: Impact of variability of space environment on communications Results on the real-time satellite and terrestrial measurements for now-casting, forecasting and warning purposes: and

The fourth WP results on Long-term trends in the ionosphere and upper atmosphere parameters concern the geomagnetic control concept that relates F and E regions parameters trends with long-term variations of geomagnetic activity. The possible role of other causes, as the consequences of the greenhouse gasses emission enhancement, are still under investigation. WG1: Impact of variability of space environment on communications

Results on a dependence of the ionospheric foF2 and foE long-term trends on the phase of geomagnetic activity

In the last decade several investigations, mainly based on mid-high latitude ionosonde data (Bremer, 1992, 1998; Ulich and Turunen, 1997, Jarvis et al, 1998), have been carried out in order to verify the possibility of a greenhouse effect in the ionosphere (Roble and Dickinson, 1989; Rishbeth, 1990; Rishbeth and Roble, 1992), even if some authors believe that the ionospheric long-term trends could be of geomagnetic origin (Mikhailov and Marin, 2000). The most debated trends are those related to the F2 layer, hmF2 and foF2. Both the ionospheric parameters seem to decrease in the last 40 years, being the decreasing rate of the order 8 km and 0.5 MHz for hmF2 and foF2, respectively. Recently Alfonsi et al. (2002) have analysed ionosonde data from mid and high latitude stations by utilizing a new Magnetic Activity Catalogue, MAC, introduced for modeling the geomagnetic activity impact on the ionosphere (De Franceschi et al., 1999). According to this investigation the foF2 trends are not, at least completely, due to magnetic origin.

Working Group 2: Assessment of space plasma effects for satellites applications The activities of the Working Group 2 are now organized in 3 Work Packages that according to the work plan started with the first one whereas the other two are still in their initial phase.

The first WP concerning the Plasma effects on GNSS applications has been active in different tasks. Among the others it is important to mention: a ) Validation of TEC estimated by different techniques by using independent measurements (among others validation of TEC calculated from ionosonde data), contacts with the International GPS Service (IGS), preparation for validation of IGS TEC map products; b) Coordinated studies for analyzing large scale ionospheric structures in particular during ionospheric perturbations (among others storm studies, trough characterization, new polar TEC maps of DLR Neustrelitz); c) Establishment of the Radio Occultation technique for probing the ionosphere (among others participation in validation of CHAMP results).

Global distribution and amplitude of night-time f0F2 data measured onboard CHAMP in 2001, days The plot shows the global coverage of the GPS ionospheric radio occultation events measured onboard CHAMP from 11 April -12 August 2001 for night-time conditions. This new monitoring technique has a big potential for near-real-time ionospheric sounding on global scale.

Comparison of CHAMP IRO retrievals with vertical sounding data NmF2 and hmF2 The comparison of the peak electron densities and heights deduced from GPS CHAMP radio occultation measurements with corresponding vertical sounding data provides a measure of the achievable accuracy for estimating local F2 layer parameters. The comparison was supported by numerous vertical sounding observations carried out in COST 271 countries.

The second WP on Assessment of plasma propagation errors in navigation systems and merits and shortcomings of novel data sources involves the following tasks: a) To assess ionospheric effects in non-ionospheric applications of GNSS signals as ionospheric influences in the use of GNSS occultation for stratosphere/troposphere applications and the effect of higher order ionospheric propagation errors in advanced ground based applications, like water vapour retrieval; b) To assess GNSS related systems to gain ionization data as Tomography, 3D and 4D imaging of the ionosphere, high resolution tomography (based on LEO beacon observations); c) To perform other assessment studies as vTEC vs Nmax behaviour or assess slab thickness behaviour.

Basis: 3D and time dependent electron density model, e.g., profilers like the IRI or Graz-Trieste model family (NeQuick,COSTprof, NeUoG-plas) troughs and ridges wavelike disturbances small scale fluctuations main trough of F region large and medium scale TIDs small scale TIDs Smaller scales Large scale existing Modulation method

ITU-R peak density modulated by the main trough COST 271, Working Group 2 Example: electron density models for assessment studies Contours of peak density in units of 10 9 m 3

The third WP on Investigation of extremes of ionization was approved during MCM2 with the following terms of reference: The WP will deal with observations with the aim to come up with reasonable occurrence statistics when possible and useful, and a collection of well documented extremes. The WP will provide a list of criteria to define type and nature of the extreme cases and to guide the data collection." Work is in the definition phase that will close by the end of April The next step is to prepare an overview on existing data (to be available at MCM4).

Working Group 3: Ionospheric effects on terrestrial communications The activities of the Working Group 3 are organised in 4 Work Packages. In the first WP, on The effects of large-scale ionospheric fluctuations on terrestrial communications, including remote sensing, radio localization and radar, the short term variability of the ionosphere, caused by gravity waves type oscillations (GWO), has been studied.

Results concern the vertical propagating signatures of GWO that are caused mainly by solar eclipse effects and solar terminator passages. Moreover the investigations of ionospheric variability caused by planetary wave type oscillations (PWO) have been carried out in order to find large-scale structures in the ionosphere. It has proved that PWO manifest each year during local summer as stationary or traveling waves (dominantly westward). Working Group 3: Ionospheric effects on terrestrial communications

WG 3: Ionospheric effects on terrestrial communications Results on the effects of large-scale fluctuations on terrestrial communications produced by: Ionospheric variability caused by the Gravity Wave type Oscillations (GWO) and the Planetary Wave type Oscillations (PWO) is limiting factor in ionospheric terrestrial communications. Time development of the probability of existence of Gravity Wave Type Oscillations during a typical day

In the second WP on Effects of small-scale ionospheric irregularities, interference and noise on terrestrial communications, the classification of middle and auroral latitudes irregularities has been organized in 6 different classes, with sub-classes. The considered irregularities produce characteristic signatures in the scattering functions. In the third WP on Mid-latitude ionospheric features in radio propagation models the investigations were concentrated on the study of sporadic E layers and spread F by reformulating the meaning of foEs and fbEs WG 3: Ionospheric effects on terrestrial communications

WP3.4 Development of methods and algorithms to minimise the effects of small and large scale fluctuations on terrestrial communications Simulated time history of the direction of arrival of an 8.65 MHz signal propagating through a model ionosphere containing patches of enhanced electron density. The main activity concern the Trillion project. The aim of this project is to achieve transmission via the ionosphere of still or slowly moving images. For this purpose, the challenge is to increase the bit transfer rate of a HF digital radio link up to 60 kbits/s, the current standard for HF modems being equal to 4.8 kbits/s in a 3kHz bandwidth. This experimental activity should also provide a confirmation that the presence of blobs and arcs in the polar cap ionosphere would produce the observed directional effects.

Working Group 4 - Space plasma effects on Earth-space and satellite to satellite communications The activities concerning the WP Effects of space plasma variability and irregularities on Earth-space and satellite to satellite communication channels are part of the HIRAC campaign. This study will be extended using data from Trömso and the results will be included in a paper to be presented at the URSI GA in Maastricht. A critical analysis of experimental techniques dealing with GPS scintillation monitors is in progress. Such an analysis is considered important because experimental data are used to assess the impact of ionospheric scintillation on satellite applications and to validate modelling efforts.

The S4 map obtained with GIM gives the expected values and geographical dependencies for S4 for both equatorial and polar regions. From A Review of Scintillations Events and Probabilities by Y. Béniguel, (Presented at the 1 st COST271 Symposium at Sopron) S4 and TEC maps for vertical links with a GPS satellite. The grid points correspond to the sub satellite points coordinates.

Concerning then Development of algorithms and software to treat disturbances in Earth-space and satellite to satellite communications a work has be done to demonstrate that the Neural Network based approaches are promising in modelling of the highly complex non-linear process involved in TEC and other ionospheric parameters variations.

The Effects of the vertical and horizontal gradients of the electron density on Earth-space and satellite to satellite communication have been studied by investigating the structure of the vertical and horizontal gradients in the topside ionosphere by using topside sounder data from the Russian Intercosmos 19 and Cosmos 1809 satellites. At present, criteria and algorithms are being developed in order to use experimental GPS derived TEC data to validate model simulation results for the slant to vertical TEC conversion factor errors. Preliminary results based on such experimental data tend to confirm the outcome of the model simulations.

Quasi longitudinal cross section of TEC between electron concentration maximum and Intercosmos 19 satellite height. The data were taken on 28/11/1979 between 11 and 15 LT and at a longitude of about 230 E. Red points indicate experimental data, blue points NeQuick model and green points IRI-95 model. The figure shows clearly the difference between the NeQuick and IRI-95 at high latitudes.

6.1 Publications and Reports Most of the papers concerning the activities of the COST271 Action have been published in the following special issues: 1. 1 st COST271 Workshop Proceedings CD Ionospheric Modelling and Variability studies for Telecommunication Applications, September 2001, Sopron, Hungary. 2. Special volume of Acta Geophysica Hungarica on the COST271 Workshop Ionospheric Modelling and Variability studies for Telecommunication Applications, in press. 3. Special volume of Annali di Geofisica dedicated to the XXVI EGS General Assembly Session on Solar-Terrestrial Sciences: Ionospheric variability and modelling, in press July 2002.

Scientific and Technical Cooperation Most part of the scientific studies performed during this last year has been obtained as result of co-operations among different countries in Europe. Moreover participants of this action are active in international projects as the HIRAC campaign or are promoting new international projects that are involving other COST271 members as DIAS a proposal on a Digital Upper Atmosphere Server submitted to the European eContent activity and ROSE a project to establish in Gaudos the southernmost land in Europe an international geophysical observatory.

Web site The Web site of the COST271 action is active on the following address: