SPEAR (Space Plasma Exploration by Active Radar) is a revolutionary new concept in ground based radar design which is intended to provide a versatile HF system for STP (Solar-Terrestrial Physics) research in the polar cap. SPEAR is not only a radar system in its own right, which will provide a major new capability for diagnosing plasma dynamics in the polar ionosphere by means of HF scatter, but also, by exploiting high power radio technology in a new way, will have an active capability of artificially stimulating VLF and ULF electromagnetic waves and short scale electrostatic plasma density waves and irregularities in the ionosphere and magnetosphere.
The different capabilities are illustrated in the schematic diagrams below.
These artificially generated waves and irregularities, once injected into the space plasma, will be detected by other ground-based radars and magnetometers and by satellite-born instruments in a controlled and co-ordinated manner which will significantly enhance our present diagnostic capabilities.
SPEAR will be located on Svalbard (Spitzbergen), which lies within the polar cap. This location is the new focus of international attention in STP and was chosen as the site for the new EISCAT Svalbard Radar (ESR). From a technical standpoint SPEAR combines the capabilities of a phased array HF radar and those of a high power ionospheric modification facility (heater). It will comprise a broad-band antenna array with a distributed high power transmitter system, capable of transmitting a steerable beam of radio waves in the frequency range 4.0 to 6.0 MHz with up to 0.2 MW of RF power.
Further information about SPEAR and the science topics it will help address, is contained in these papers which are available as pdf files for download. Adobe Acrobat Reader is required to view these files and this is available free from the Adobe Web site.
Warning - Some of these files are large!
Space Plasma Exploration by Active radar (SPEAR): an overview of a future radar facility (402 KB)
D.M Wright, J. A. Davies, T. R. Robinson, P. J. Chapman, T. K. Yeoman, E. C. Thomas, M. Lester, S. W. H. Cowley, A. J. Stocker, R. B. Horne, F. Honary, Ann. Geophysicae 18, 1248-1255 (2000)
Fast observations of ULF waves injected into the magnetosphere by means of modulated RF heating of the auroral electrojet (1.4 MB)
T. R. Robinson, R. Strangeway, D. M. Wright, J. A. Davies, R. B. Horne, T. K. Yeoman, A. J. Stocker, M. Lester, M. T. Rietveld, I. R. Mann, C. W. Carlson, and J. P. McFadden, GRL, Vol. 27, No. 19, 3165-3168, October 2000
ULF waves with drift resonance and drift-bounce resonance energy sources as observed in artificially-induced HF radar backscatter (373 KB)
T. K. Yeoman and D. M. Wright, Annales Geophysicae (2001) 19: 159170
High spatial and temporal resolution observations of an impulse-driven field line resonance in radar backscatter artificially generated with the Tromsø heater (1.9 MB)
Yeoman, T. K., D. M. Wright, T. R. Robinson, J. A. Davies and M. T. Rietveld, Annales Geophysicae, 15, 634, 1997.
High resolution bistatic HF radar observations of ULF waves in artificially generated backscatter (228 KB)
Wright, D. M. and T. K. Yeoman, Geophysical Research Letters, 26, 2825, 1999.
CUTLASS observations of a high-m ULF wave and its consequences for the DOPE HF Doppler sounder (1.4 MB)
Wright, D. M. and T. K. Yeoman, Annales Geophysicae, 17, 1493, 1999.
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