First results of artificial stimulation of the ionospheric Alfvén resonator at 78°N

Scoffield, H. C.; Yeoman, T. K.; Robinson, T. R.; Baddeley, Lisa; Dhillon, Ranvir; Wright, D. M.; Raita, Tero; Turunen, T.

doi:10.1029/2006gl027384

Cited by 10 publications

(14 citation statements)

References 19 publications

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“…Observations of modulations in both the north-south and east-west components of the ground magnetic field have previously been made (e.g. Scoffield et al, 2006), so our results are not unusual for non-ideal experimental conditions.…”

Section: Ground Magnetometer Measurementssupporting

confidence: 64%

“…A full description of SPEAR and its operational capabilities is given by Wright et al (2000) and Robinson et al (2006). Among many results from SPEAR experimental heating campaigns run so far, ground magnetometer data have provided evidence of stimulation of the local IAR at Hz frequencies (Scoffield et al, 2006), and excitation of open field lines at mHz frequencies (Clausen et al, 2008). This paper describes a similar experiment when SPEAR modulated ionospheric currents at 1 Hz and 1.67 mHz, and enhanced a field line resonance at 1.67 mHz on closed field lines.…”

Section: Introductionmentioning

confidence: 99%

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Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)

et al. 2009

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Abstract. Space Plasma Exploration by Active Radar (SPEAR) is a high-latitude ionospheric heating facility capable of exciting ULF waves on local magnetic field lines. We examine an interval from 1 February 2006 when SPEAR was transmitting a 1 Hz modulation signal with a 10 min onoff cycle. Ground magnetometer data indicated that SPEAR modulated currents in the local ionosphere at 1 Hz, and enhanced a natural field line resonance with a 10 min period. During this interval the Cluster spacecraft passed over the heater site. Signatures of the SPEAR-enhanced field line resonance were present in the magnetic field data measured by the magnetometer on-board Cluster-2. These are the first joint ground-and space-based detections of field line tagging by SPEAR.

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Section: Ground Magnetometer Measurementssupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)

et al. 2009

Self Cite

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“…Trakhtengerts and Feldstein, 1991;Lysak, 1993;Pokhotelov et al, 2003), and artificial excitation (e.g. Bösinger et al, 2000;Scoffield et al, 2006). The present paper is the first dealing with magnetic inclination effects which are expected to be detectable at low latitudes.…”

Section: Introductionmentioning

confidence: 82%

Magnetic-inclination effects in the spectral resonance structure of the ionospheric Alfvén resonator

et al. 2009

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Abstract. Based on recent developments in the formalism governing the spectral resonance structures (SRS) of the Ionospheric Alfvén resonator (IAR) as observed on the Earth's surface, a numerical code was developed to investigate properties of SRS which can in particular be contributed to magnetic inclination effects. Among the theoretical findings are: 1) SRS is discernible in both orthogonal components, 2) the harmonic structure of SRS is not anymore over frequency equidistantly distributed, 3) the frequency scales of SRS differ in the two normal modes. The theoretically predicted properties could be found in the observations of a low latitude and some of them even in the data of a mid latitude station. The verification, however, is not as straight forward because the predicted effects do not only depend on magnetic inclination but also on the wave angle of the lightning induced electromagnetic wave k-vector with the normal to the magnetic meridian passing through the observation site. So far the formalism is simplified as it deals with a single source situation alone whereas the actual observation is a composite of excitations caused by an average of about 60 flashes of lightning operating all the time, world-wide.

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“…The D component peak was 1.6 times the magnitude of the H component peak. The bar at the top of the figure and the vertical dashed lines indicate when the heater was turned on (red) (Scoffield et al, 2006). …”

Section: Discussionmentioning

confidence: 99%

“…The transmitters were operated at 2kW, resulting in an ERP for SPEAR of ~ 15 MW. On 2 December 2005, as recently reported by Scoffield et al (2006), a modulated X-mode ionospheric modification experiment was carried out at SPEAR, with the intention of artificially stimulating the Ionospheric Alfvén Resonator. A modulation frequency of 3 Hz was superimposed on a 20 minute on/off cycle.…”

Section: The Polar Capmentioning

confidence: 99%

Investigation of natural and artificial stimulation of the ionospheric Alfvén resonator at high latitude

Yeoman

Scoffield

Wright

et al. 2008

Advances in Space Research

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A brief review is provided of recent progress in understanding the Ionospheric Alfvén Resonator (IAR) at high latitude. Firstly, naturally-occurring resonances of the IAR as detected by pulsation magnetometers in the auroral zone at Sodankylä and in the polar cap at Barentsburg are considered. The characteristics of the IAR in the two regions are broadly similar, although the effects of solar illumination are less clear at the higher latitudes. Secondly we review recent attempts to stimulate the IAR through high-power radio frequency experiments both in the auroral zone at Tromsø with the European Incoherent SCATter (EISCAT) heater, and within the polar cap at Longyearbyen with the Space Plasma Exploration by Active Radar (SPEAR) facility. In the auroral zone at, Tromsø the stimulated IAR has been observed by ground-based magnetometers, and through electron acceleration observed on the FAST spacecraft. At SPEAR in the polar cap, the stimulated IAR has been investigated, with ground magnetometers, with the first results indicative of a positive detection.

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First results of artificial stimulation of the ionospheric Alfvén resonator at 78°N

Cited by 10 publications

References 19 publications

Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)

Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)

Magnetic-inclination effects in the spectral resonance structure of the ionospheric Alfvén resonator

Investigation of natural and artificial stimulation of the ionospheric Alfvén resonator at high latitude

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