J. Geomag. Geoelectr., 47, 669-679, 1995

The EISCAT Scientific Association and the EISCAT Project

J. ROTTGERI, U. G. WANNBERG1, and A. P. VAN EYKEN2

1EISCAT Scientific Association , P.O. Box 812, 5-981 28 Kirnna, 2Ramfjordmoen, N-9027 Ramfjordbotn,

(Received April 16, 1995; Revised June 29, 1995; Accepted June 30, 1995)

A brief introduction of the EISCAT Scientific Association is given. The history of the evolution of EISCAT by adding the EISCAT Svalbard Radar (ESR) to its facilities is summarized. The scientific rationale to use the ESR is reproduced and the technical specifications and the management, the construction and the present status of the project are described in brief.

1. The EISCAT Scientific Association

EISCAT, the European Incoherent Scatter Scientific Association, is established to conduct research on the middle and upper atmosphere, and the using the incoherent scatter radar technique. This technique is the mostpowerful ground-based tool for these research applications. EISCAT is also being used as a coherent scatter radar, for studying instabilities in the ionosphere, as well as for investigating the structure and dynamics of the middle and lower atmosphere and as a diagnostic instrument in ionospheric modification experiments, called Heating. The EISCAT UHF radar operates in the 931 MHz band with a peak transmitter power of 1.5 M W and 32 m, fully steerable parabolic dish antennas. The transmitter and one receiver are in Tromso in Norway. Receiving sites are also located near in Sweden and near Sodankyla in , allowing continuous tristatic measurements. The monostatic VHF radar in Tromso operates in the 224 MHz band with a peak power of 2 x 1.5 MW and a 120 m x 40 m parabolic cylinder, which is subdivided in four sectors. It can be steered from vertical to 60 degrees north and to 12 degrees east and west of the zenith. The basic data measured with the incoherent scatter radar are profiles of electron density, electron and ion temperature and ion velocity. Subsequent processing also allows a wealth of further parameters, describing the ionosphere, upper atmosphere and mesosphere, to be derived from these. Also troposphere and stratosphere observations are occasionally performed. A selection of well-designed radar pulse schemes allows the adaptation of the data-taking routines to many particular phenomena, occurring at altitudes between about 3 km and more than 1800 km. Depending on geophysical conditions, a best time resolution of better than one second and an altitude resolution of better than a few hundred meters can be achieved, whereas typical resolutions are of the order of minutes and kilometers. Each year, nominally 1500 operating hours are distributed equally between Common Programmes (CP) and Special Programmes (SP). At present seven well-defined Common Programmes are run regularly, for between one and five days, about 25 times each year to provide a data base for long term synoptic studies. Three Unusual Programmes (UP) are started ad hoc during particular geophysical conditions. A large number of Special Programmes, defined individually by associate scientists, are run to study a variety of specific geophysical events. Scientific topics of the research done using EISCAT data comprise for instance: The aurora and substorms, high latitude convection and electrodynamics, ionosphere-thermosphere coupling, atmospheric waves and tides, ionospheric structure, irregularities and modelling, the middle and lower atmosphere, plasma physics and ionospheric modification using the EISCAT as diagnostics. Further details of the EISCAT system, operation and the scientific research can be found in the

669 670 1. ROTTGER et at. literature (e.g., proceedings of EISCAT workshops in the Journal of Atmospheric and Terrestrial Physics etc.), and in various EISCAT reports, particularly the series of Annual Reports (e.g., 1992, 1993), including illustrated brochures which can be obtained from EISCAT Headquarters at the address given in the title. The investments and operational costs of EISCAT are shared between the six associated national scientific research organizations, the EISCAT Associates who signed the original agreement and of 1975. These are the Suomen Akatemia (Finland), Centre National de la Recherche Scientifique (France), Max- Planck-Gesellschaft (), Norges forskningsrad (Norway), Naturvetenskapliga Forskningsradet (Sweden) and the Particle Physics and Astronomy Research Council (). The total capital investment and accumulated operating costs since the beginning of the operation in 1981 amount to more than 270 million Swedish Crowns (MSEK) distributed between the Associates. Almost three-quarters of the original investment were allocated to the provision of the major hardware components particularly the transmitters and antennas. The annual operating budget is presently about 25 MSEK. The EISCAT Council, the Administrative and Finance Committee and the Scientific Advisory Committee with members from each of the six Associates are governing the operation of the EISCAT Scientific Association. The executive consists of a Directorate and support staff at the Headquarters, and further scientific and technical staff are located at each of the three experimental sites in Kiruna, Sodankyla and Tromso. The EISCAT Scientific Association is now constructing an additional radar site. This project is called the EISCAT Svalbard Radar (ESR), and is located on Spitsbergen in the archipelago of Svalbard north of the Norwegian mainland. Svalbard has the advantage of being located inside the auroral oval and the Arctic where fundamental ionospheric and atmospheric phenomena shall be studied. A suitable radar site has been established close to , the largest Norwegian settlement on the main island Spitsbergen, where the antenna has been erected and operations building been constructed. Presently the radar equipment is being installed in the building. The EISCAT Svalbard Radar will be the world's most advanced research facility of this kind and is assumed to attract users from many countries.

2. The EISCAT Svalbard Radar Project

2.1 The historical development Svalbard offers a site unique in the Northern hemisphere in that long periods of midday darkness are encountered in a region where the complex processes occurring in the cusp region of the ionosphere can also be observed. As a result ofthis the idea ofplacing a modem incoherent scatter facility on these islands was reintroduced in 1989 in a report written for the Science and Engineering Research Council of the United Kingdom. This report was subsequently presented to the EISCAT Council, which established a sub-committee to prepare the EISCAT Cap Radar Report (Bjoma et al., 1991), which was accepted by the Council in 1991 and on which formed the basis of this new project. During the EISCAT Council meeting on 12-13 November 1992 in Uppsala, Sweden, the Council approved the project planning and unanimously decided to begin the construction of the new radar, which is called the EISCAT Svalbard Radar (ESR). On 30 June 1993 all six EISCAT Associates had signed the Agreement on the Svalbard Radar (EISCAT Annual Report, 1993). The basic specifications of the ESR system had been presented and largely frozen at the ESR Design Review Meeting in Yllasjarvi, Finland, in September 1992. The global system specifications, the management, the personnel and the financing plan were presented to the Council and were generally adopted. In the EISCAT Annual Reports (1992,1993) and in a brochure "The EISCAT Svalbard Radar- An Evolutionary Step into EISCAT's Future" (1993) one finds the history of major milestones of the ESR planning, the basic lay-out of construction phases of the ESR, a summary of the project management plan, a time schedule of critical milestones and actions, the personnel and financing plan and the full abridged description of site and instrumentation of the EISCAT Svalbard Radar. The total costs of the ESR construction are estimated at about 150 MSEK. This includes new funds from the Associates and work The EISCAT Scientific Association and the EISCAT Svalbard Radar Project 671 I

Polar Cap CuspAL [Oval /

aISarT SvafhardRadar z~~ )&UU Ell A Kiruna, Sodan. kyla,Tromso;

o e

Fig. 1. Locations and possible beam directions of the EISCAT Svalbard Radar and the EISCAT Kiruna-Sodankyla-Tromse systems,

by the EISCAT staff, paid through the regular operating budget. The EISCAT Svalbard Radar will be operated and used under principally the same conditions as the present EISCAT facilities on the North European mainland. Figure 1 shows the combined operations of the EISCAT mainland system Kiruna-Sodankyla-Tromso (KST) and the EISCAT Svalbard Radar (ESR). It is planned that will become a partner of the EISCAT Scientific Association and supply an additional antenna for the EISCAT Svalbard Radar.

2.2 The scientific rationale for the EISCAT Svalbard Radar The scientific reasoning for the radar on Svalbard are described in detail in the report by Bjema et al. (1991), and in the publication by Cowley et al. (1990). A summary of the report by Bjernd et al. (1991) was published by ROttger (1991) in the ESA proceedings of the Cluster Workshop on Svalbard in September 1991. Here we summarize the highlights of the scientific expectations of this new EISCAT Svalbard Radar project. Further scientific applications are described in articles published in this issue of the Journal on Geomagnetism and Geoelectricity. It is understood that solar terrestrial research has reached a stage when it is necessary to put greater emphasis on a comprehensive study of the links between the various regions of space from the to the . The generation, flow and dissipation of energy together with the transfer of energy, mass and momentum from the solar to the and between the magnetosphere, ionosphere, thermosphere, middle and lower atmosphere are regarded to be of major importance. Accordingly, the international programme of research in solar-terrestrial physics, the Solar-Terrestrial Energy Program STEP, is being carried out during this decade. There are significant elements in STEP and also in the Geospace Environment Modeling program GEM that include particular spacecraft missions supported by ground based observations to study solar-terrestrial relations (, 1993). It is also foreseen that the Cluster spacecraft mission of the European Space Agency (ESA) will substantially contribute to these investigations. It is further expected that contributions to the environmental studies and the Global Change Programme will be made by radar studies of effects in the high latitude Arctic stratosphere and troposphere. It is recognized that the outstanding success of EISCAT has led to improved understanding of auroral 672 J. ROTTOER et all ionospheric physics, its relation to plasma physics and electrodynamics and in particular the coupling between the magnetosphere and the ionosphere. However, magnetic reconnection at the dayside and particle acceleration processes in the cusp region of the magnetosphere are not yet fully understood, and can be studied by the powerful combination of incoherent scatter radar and satellite-borne and other instrumentation. EISCAT has improved our knowledge of many of the long-established problems of the auroral zone, but even more exciting work leads us further north, to the cusp and the polar cap, where the ionosphere is linked to the interplanetary medium along open magnetic field lines. This region is the most crucial in the transfer of energy and momentum from the into the magnetosphere and hence into the ionosphere, thermosphere and middle atmosphere, which are barely explored in the polar cap. The sunward side of the oval, the cusp region, is usually at latitudes around 80°N, which is above Svalbard. Indications given by EISCAT, operating at the very limit of its range capabilities towards the north, point emphatically to an advanced incoherent scatter radar at the very high latitudes of Svalbard. In Fig. 2 the field of view of the EISCAT Svalbard Radar is shown at different magnetic local times (MLT). G is the North geographic pole, M is the North geomagnetic pole at 24 MLT and the inner shaded ring is the auroral oval. The EISCAT Svalbard Radar field of view would cover fully the cusp region, the northern boundary of the auroral oval and most of the polar cap. This field of view (hatched in the figure) would properly complement the present EISCAT radars, which are located approximately at the equatorward boundary of the Svalbard Radar field of view. The extension of EISCAT by a radar facility on Svalbard will therefore support major advances both in the understanding ofthe whole chain of solar-terrestrial relationships and in the study ofplasma physics. W e outline here a few relevant examples of special scientific investigations which should be extended into the magnetospheric cusp region, the polar cap ionosphere and the Arctic middle and lower atmosphere by using the EISCAT Svalbard Radar. Ionospheric signatures ofmagnetospheric cusp/cleftprocesses would provide deep insight into solar- wind magnetosphere interactions, in particular the dayside aurora] and plasma flow transients, Birkeland currents and the cusp/cleft fountain.

12 MLT

T., 6

24 MLT

Fig. 2. Field of view of the EISCAT Svalbard Radar (hatched ring). The inner stippled ring is the aurora] oval, G the geographic and M the geomagnetic pole, respectively. The lines with arrows indicate the plasma flow over the polar cap (after RSttger, 1991). The EISCAT Scientific Association and the EISCAT Svalbard Radar Project 673

The electrostatic potential over the polar cap ionosphere and the convection pattern are determined by the transfer ofmatter, energy and momentum from the solar wind into the magnetosphere. The response of the polar cap convection pattern to the orientation of the interplanetary magnetic field, in particular the splitting into the multi-cell pattern during strong northward interplanetary magnetic field component, will for instance properly be observed by the EISCAT Svalbard Radar. The EISCAT facilities extended by the EISCAT Svalbard Radar will provide essential information on polar cap convection, polar cap particle precipitation, coupling of the amoral oval and the polar cap, extraction of ionospheric plasma by magnetospheric processes, large upward flows of ions in the midnight sector and the . The polar cap ionosphere and thermosphere are still poorly understood regimes of the terrestrial upper atmosphere. Necessary observations with the EISCAT Svalbard Radar will include studies of the ionization, composition and thermal structure ofthe polar cap ionosphere, the cusp region, the morphology of patches, blobs and irregularities of ionization, the thermospheric response to the interplanetary magnetic field and the sources andpropagation of atmospheric gravity waves generated in the aurora] oval and the polar cap. Studies of the Arctic mesosphere, stratosphere and troposphere with a radar on Svalbard will yield valuable information about coupling processes as well as the dynamics and structure of these regions and their climatology. There are indications of anthropogenic changes in the aeronomy of the polar mesosphere, which might be most sensitive indicators of global change and can be studied by radar. Tropopause foldings are observed by radar, and can be regarded as a lower altitude neutral atmosphere equivalent to the magnetospheric cusp region. Dynamical processes, which exchange constituents between the troposphere and the stratosphere, can be measured by radar. Studies of the tropospheric and stratospheric dynamics, such as waves and turbulence, will also contribute to improvements in the understanding of ozone variations in the Arctic, which has relation to the global climate change. In addition to the geophysical aspects of such studies in the polar cap and the Arctic, the polar cap and cusp/cleft region are natural laboratories where basic plasma processes can be studied, such as non- thermal plasma, instabilities and plasma heating, waveparticle interaction and magneto-hydrodynamic waves. Many of these radar observations will be carried out within international programs and campaigns in which differentkinds ofadditional instrumentation, such as advanced ground based optical (interferometer and airglow observations etc.) and other radio methods (e.g., imaging riometers, HF and VHF radars), lidar and rockets etc., will also be used. In particular, collaborations with international space missions will greatly enhance the scientific importance of the ground-based observations by the EISCAT Svalbard Radar (Opgenoorth, 1993). Vital complementary observations for the spacecraft missions, in particular the Cluster spacecraft of the European Space Agency (1993) are expected. Lockwood et al. (1995) gave outlined in quite some detail the ground-based support for the Cluster mission, and aspects for the opportunities and radar modes for magnetospheric research using the EISCAT Kiruna-Sodankyla- Tromso and the EISCAT Svalbard Radar are described by Lockwood and Opgenoorth (1995, in this issue). Model simulations to reproduce ionospheric observations above Svalbard are published by Alcayde et al. (1994).

2.3 A general system description of the ESR The EISCAT Svalbard Radar (ESR) has been specified as a high-standard research instrument for the studies outlined in this article and this special issue ofthe Journal of Geomagnetism and Geoelectricity. The radar site is located near Longyearbyen, the main settlement on Spitsbergen, which is part of the Svalbard archipelago. The map on Fig. 3 shows the location of Longyearbyen on Svalbard in the Arctic and polar cap with respect to the geographic (GP) and the geomagnetic (MP) poles, and the location of Kiruna, Sodankyla and Tromso. The operating frequency of the ESR is near 500 MHz. A modular transmitter will operate at 500 kW peak power in the initial phases. It's modular design allows upgrading to 1 MW (eventually 2 MW) in a 674 1. ROTTOER et al.

I Q ,-f _T ------

b 6

F-S.

c

.6

rtba

XX EISCAT rraas

%_$5W ptlan,yla' --

Fig. 3. Map of the Arctic, centered around the geographic pole G, showing the polar cap, centered around the geomagnetic pole M, and the locations of Longyearbyen/Svalbard, Kiruna, Sodankyla and Tromse (after Bjem& et al., 1991).

follow-up phases. The antenna is a parabolic dish of 32 m diameter. Further antennas of this kind can be added in an expansion phase. It is presently envisaged to add a second antenna as the Japanese contribution to this project, and appropriate provision is made for this purpose in the design and construction of the radar site, building and instrumentation. The radar control, monitoring and digital data processing of the ESR apply contemporary standard digital equipment and sophisticated software. It is anticipated that this EISCAT Svalbard Radar system will become the most modem one of it's kind on the world. The design and management of the ESR project are in hands of the EISCAT directorate, supported by the administrative executive and the EISCAT technical/scientific staff. The project management plan consists of well defined, structured work packages. All these work packages have been precisely developed and specified. The development of the workpackages, which are described in detail in the ESR System Description Document (EISCAT, 1994a), were monitored in regular management meetings. In the following some of the technical specifications of the EISCAT Svalbard Radar are described. The main hardware components are depicted in the block diagram shown in Fig. 4 and the basic technical specifications are found on Table 1. Further features of the ESR project are published in the EISCAT Annual Reports (1992, 1993). Detailed descriptions of the technical design (Wannberg et al., in prepa- ration) and the scientific user software (van Eyken et al., in preparation) of the ESR will be published elsewhere. Here only a brief outline is presented. The design philosophy behind the EISCAT Svalbard Radar system is to use high-technology industry standard components and subsystems wherever possible. Non-standard solutions have been adopted where the scientific requirements could not be met on the commercial market. In-house design, development and construction of non-standard parts by experienced staff did allow to meet very tight system completion time targets and to keep the system costs low. This philosophy has resulted in the selection of an antenna adapted for the Arctic climate, a transmitter modified for special radar demands, dedicated RF generation and front-end receiver components, specific digital signal processing, radar controllers and monitor as well as extensive control and real-time display and user software developed in- house and through in-kind contributions from EISCAT Associates' institutions. The antenna for the EISCAT Svalvard Radar was supplied by a Swedish company. Provision is made The EISCAT Scientific Association and the EISCAT Svalbard Radar Project 675

Analog RX

Main Console

Fig. 4. Basic block diagram of the EISCAT Svalbard Radar instrumentation.

to add further antennas to the ESR. The antenna main reflector of 32 m diameter, sub-reflector and feed horn (Cassegrain feed) are optimized to provide very high requirements for low side-lobe emissions which are required for an antenna installed on the selected site near Longyearbyen (Fig. 5) in order to avoid problems with excess clutter returns as well as eliminating problems in other locally sited equipment. A turning-head design was adopted in deference to the relatively harsh Arctic environment. The antenna equipment must operate and maintenance activities must be performed in this unusual environment. The ESR antenna is movable overmore than 360° in azimuth and from 0° to 180° elevation and has again larger than 42 dBi. The antenna is controlled individually or through the main radar console. Weather data are acquired and used to limit antenna motions or move the antenna into stow position depending on weather conditions. An aircraft warning radar is required to prevent high power transmission when aircraft are close to the radar site. The EISCAT Svalbard Radar transmitter is constructed in a highly modular form giving improved system reliability, and the possibility to continue operation even if some modules have failed, and ease of maintenance. In addition, this approach allows phase differences to be introduced between the outputs of different parts of the transmitter in order to use a waveguide combiner as a switch to direct the output power between more than one antenna during the expansion phase. Each module (Amplifiers) of the transmitter consists of two transmitter modules individually providing 125 kW peak output power. These transmitter modules, manufactured according to EISCAT specifications by a company in the United Kingdom, are based on a design which has already been produced in substantial quantities. The design uses two standard, external cavity, commercial television klystrons. The transmitter modules are each provided with conservatively rated, fast solid state modulat- ing anode pulsers to achieve the required low interpulse noise levels. Pulse rise and fall times of 10µs and pulse repetition rates of up to 10 kHz can be achieved by these pulsers allowing a substantial program of low altitude stratosphere-troposphere observations to be addressed. The power supplies are air-cooled and integral with the individual transmitter module cabinets; at only 24.5 kV DC beam voltage, neither crowbars nor oil-filled components are used. The outputs of each pair of klystrons are fed through harmonic filters and combined in a switchless waveguide combiner which also allows the modules to be tested into a dummy load and the optimization of the module output in the case of a partial failure. The outputs of the various modules are combined in a similar manner, with all waste loads being over-rated to safely absorb any out of balance condition 676 1. ROTTGER et al.

Table I . Basic system specifications of the EISCAT Svalbard Radar.

The EISCAT Svalbard Radar System Specifications 1995

Location: near Longyearbyen 78°09'N, 16°03'E on Spitsbergen, Svalbard

Operating Frequency: 500 MHz

Bandwidth: Transmitting: t 2 MHz Receiving: t 10 MHz

Antenna. Parabolic dish, one (upgradable to >1) Beamwidth: 1.6° (one-way) Gain: 42 dBi Aperture: 500 m' Polarization: circular Steerability: all azimuths, 0-180 degrees elevation

Transmitter Peak Power 0.5 MW, modular system (upgradable to 1MW) Average Power 0.125 MW Tubes: TV-klystrons(8) Pulse Length: < 1 ps - 2 ms Modulation: amplitude and phase coding Interpulse: min. 0.1 ms Radar controller: Program memory: address space 20 bits 1 MW memory 32 bit control word with 100 ns resolution

Receiver. Dual superheterodyne Noise temp.: 5 20K System Temp.: 5 100 K IF: 70 MHz ± 5 MHz Output channels: up to 6 ADC: 10 MHz min. 12 bit min. Complex digital mixer and filter: Digital multiplier: 10 MHz bandwidth FIR fitter. 10 MHz data rate 16 bit coeff. accur.

Digital Signal Processing: Narrow- and wide-band Bus environment: VME Host processor: Spars and 58040 Lag profile proc.: TMS'C40x4 at 50 MHz Input data format 16+16 bit complex Output data format. 32+32 bit complex Processing rate: 30 MOPS/channel

Total System Figure of Medt: Peak Power x Aperture per System Temp.: 2.5 MW m2/K

without interruption to the operations. The initial transmitter will use only two modules to yield a peak output power of 0.5 MW at 25% duty cycle. Space is available in the building to add additional transmitter units to rise the power to 1 MW. Following the orthogonal-mode transducer (OMT) and the receiver protector (RX-Prot) the receiver accepts the 500 MHz analogue RF signal (Pre-Amp and Analog RX) and outputs a digital data stream representing a suitably processed function of the signal voltage. The receiver chain is configured as a dual The EISCAT Scientific Association and the EISCAT Svalbard Radar Project 677

EISCAT Svalbard Radar System

Data Processing User Data Access System EISCAT Monitor Raw Data Visualisation Data Post Integration and Archive Data Analysis Control VectorVelocity System • H System Analysed Data Visualisation Date ArchWaSystem _.:,

Rader Control System

Dl9MI signal Procasen RECEIVER ANALOG FRONT-END RECEIVER

Fig. 5. Basic block-diagram of the software elements communicating with the hardware.

super-heterodyne with a first intermediate frequency at 70 MHz and a second at 7.5 MHz. The second intermediate frequency will be sampled at 10 MHz with 12-bit resolution (ADC) and further frequency translation (Dig. Mix), filtering (FIR), rate decimation and/or resampling performed in the digital back- end before final digital signal processing (DSP). In addition to the processed digital output, the raw 10 MHz data sample stream will be available for direct recording or special purpose analysis with add-on signal processing systems. The receiver is fully phase coherent and will also be used to monitor continuously the actual transmitter output waveform in phase and amplitude allowing this information to be used directly in the data processing routines to support unprecedentedly accurate signal correction and calibration. Synchronized by a main time base, the receiver and transmitter are controlled by separate radar controllers (RX-RC and TX-RC). The Digital Signal Processing (DSP) capability, controlled by the main console, include the computation of both lag profiles and frequency power spectra, handling modulations coded in amplitude and phase as dictated by the range and frequency resolutions required by different experiments. The digital signal processor is an integral part of the data acquisition system built into the receiver back-end, as opposed to a separate unit as in the present EISCAT system, and other existing IS radars. It is constructed using modified, commercial produced DSP boards. The ESR software system consists ofprocesses which act together to control the radar hardware, store the resulting data, and also provide access to the real-time data stream for visualization and analysis. A short executive summary of the software is found in EISCAT (1994b). Figure 5 shows a simplified block diagram of the software, which is divided into main levels consisting of an experimenter oriented interface to the user control and monitor system and the access to the data processing system. This user-oriented level, in which also the data recording and archiving is performed, communicates with the radar control system. Operators have access to these system parts. The radar control system is in charge of the real-time tasks and controls directly the corresponding hardware devices from where also the raw data are 678 1 ROTTCFR 11 nL

^c

Fig. 6. The EISCAT Svalbard Radar site with the 32m-dish antenna under construction (October 1994), and the view towards the north-west into Adventdalen (photo NTG).

transferred. The specified radar state and the resulting data are contained in so-called C-structures. These structures have a top-half, containing the user-oriented information, and a bottom half containing the actual hardware description. The whole scheme is built up on UNIX-based workstations, and the main console will consist of a SPARCserver 1000. The data analysis will be performed by the Grand Unified Incoherent Scatter Design and Analysis Package (GUISDAP, 1994). This package as well as other user- oriented software is being provided as in-kind contributions by Associates of EISCAT. Basing on this lay-out, remote monitoring and control capability of the ESR system is envisaged, at least for the standard experiment modes, and there exist plans for an ESR science operations centre to be established in the community of Longyearbyen. The introduction of telescience is planned for a later phase. The EISCAT Svalbard Radar site is located on a plateau over-looking the Advent valley to the north- east and is close to one of the two working coal mines near Longyearbyen. Figure 6 shows the antenna during erection on site. Access to the site is via a steep road with several hair-pin bends which climbs from the valley to a height of some 400 m above sea level by the end of the existing road at the entrance to the coal mines. A new road continues upwards a further kilometer across the plateau, and about 30 m higher than the mine entrance, to the site of the ESR. In order to minimize the impact on the fragile permafrost landscape and minimize environmental impact, every effort has been made to use existing tracks and roads as the foundation of the new access road, and to reduce the site area as much as possible.

3. Conclusion

So far the ESR project development is on schedule (June 1995). The transmitters and further equipment are being installed in the building and the antenna is erected on site. Tests of transmitters, antenna and digital as well as analog receiving and processing equipment take place during summer 1995. This equipment is planned to be shipped to Svalbard before the winter 1995/96. It is intended to commence limited test operations of the ESR at the end of this year 1995 and with common programme type experiments in 1996, in time to collaborate with the ESA Cluster satellite mission. Scientific user software The EISCAT Scientific Association and the EISCAT Svalbard Radar Project 679 will be imported in 1996. The EISCAT Svalbard Radar will be further developed in the subsequent years. It is, thus, anticipated that the EISCAT Svalbard Radar, hopefully also extended by a second antenna, will contribute significantly to the research of the Earth's magnetosphere-ionosphere-atmosphere environment.

This article bases on several documents and reports of the EISCAT Scientific Association and is composed of parts thereof. It is compiled as a contribution to the special issue of the Journal of Geomagnetism and Geoelectricity resulting from oral presentations at the Japan-EISCAT Symposium on the Polar Ionosphere (JESPI) held 31 August to 3 September 1994 in Toba, Japan. The dedication of Professors N. Matuura and R. Fujii, impressively convening this symposium and soliciting this article, is highly appreciated. Our sincere thanks are directed to the staff of EISCAT, who in a very committed manner contribute effectively to the success of the ESR project performance. We appreciate the preparation of the software and hardware diagrams by A.-L. Piippo and R. Hund, respectively. The investment and operational costs of the EISCAT Scientific Association are shared between the Suomen Akatemia (Finland), Centre National de la Recherche Scientifique (France), Max-Planck-Gesellschaft (Germany), Norges forskningsrad (Norway), Naturvetenskapliga Forskningsradet (Sweden) and the Particle Physics and Astronomy Research Council (United Kingdom).

REFERENCES

Alcayde, D., P.-L. Blelly, and J. Lilensten, General Ionosphere Visualization and Extraction from a Model for the EISCAT Svalbard Radar (giveme), EISCAT Techn. Note, 94/52, 1994. BjemA, N., B. Hultqvist, W. Kofman, J. R6ttger, K. Schlegel, T. Turunen, and D.M. W illis, The EISCAT Svalbard Radar, Report on the design specifications for an ionospheric and atmospheric radar facility based on the archipelago of Svalbard, EISCAT Headquarters, Kiruna, Sweden, 1991. Cowley, S. W. H., A. P. van Eyken, E. C. Thomas, P. L 5. Williams, and D.M. Willis, Studies of the cusp and amoral zone with incoherent scatter radar: The scientific and technical case for a polar cap radar, J. Atmos. Terr. Phys., 92, 645-663, 1990. EISCAT Scientific Association, Annual Report, EISCAT Headquarters, Kiruna, Sweden, 1992, 1993. EISCAT Scientific Association, The EISCAT Svalbard Radar-An Evolutionary Step into EISCAT's Future, EISCAT Headquarters, Kiruna, Sweden, Sep. 1993. EISCAT Scientific Association, EISCAT Svalbard Radar System Description Document, compiled by A. P. van Eyken, EISCAT Headquarters, Kiruna, Sweden, 1994a. EISCAT Scientific Association, EISCAT Svalbard Radar Software System, Executive Summary, EISCAT Council (94) Appendix 11.6a, November 1994b. European Space Agency, Cluster: mission, payload and supporting activities, ESA SP-1159, 1993. GUISDAP, Grand Unified Incoherent Scatter Design and Analysis Package, Report on the GUISDAP Workshop 9-13 May 1994, published by Rutherford Appleton Laboratory, Chilton, Dideot, 1994. Lockwood, M. and H. Opgenoorth, Opportunities for magnetospheric research using EISCAT/ESR and Cluster, J. Geomag. Geoelectr., 47, this issue, 699-719, 1995. Lockwood, M., R. Stamper, M. N. Wild, and H. Opgenoorth, Ground-based measurements in supportofCluster: An on-line planning procedure, RAL Report RAL-95-018, Cluster/Ground-based Data Centre WDC-Cl, Rutherford Appleton Laboratory, Chilton, Didcot, UK, 1995. Opgenoorth, H. J., Coordination of ground-based observations with Cluster, ESA SP-1159, 301-305, 1993. Rottger, J., Plans for the EISCAT Svalbard Radar, ESA SP-330, 203-210, 1991.