Stereo CUTLASS - A new capability for the SuperDARN HF radars

Lester, M.; Chapman, P. J.; Cowley, S. W. H.; Crooks, S. J.; Davies, J. A.; Hamadyk, P.; McWilliams, K. A.; Milan, S. E.; Parsons, Matt; Payne, D. B.; Thomas, E. C.; Thornhill, J.; Wade, N. M.; Yeoman, T. K.; Barnes, R. J.

doi:10.5194/angeo-22-459-2004

Cited by 89 publications

(76 citation statements)

References 38 publications

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“…The radar can operate two different modes simultaneously (Lester et al, 2004), the two modes being referred to as channels A and B. In this paper we analyse data from channel B only which operated a single beam (beam 5) that passes approximately through the centre of the heated region.…”

Section: Instrumentationmentioning

confidence: 99%

Multi-frequency HF radar measurements of artificial F-region field-aligned irregularities

et al. 2004

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Abstract. We present radar backscatter power measurements using the CUTLASS HF radar at Hankasalmi, Finland from F-region field-aligned irregularities induced by HF radio pumping with the EISCAT Heating facility. A novel radar operating mode is used in which the radar frequency is rapidly swept through a number of bands, making use of the varying ionospheric refraction to probe different heights within the heated region. We obtain height profiles of backscatter power which correspond to e-folding scale lengths of around 20 km for the mean-square electron density perturbations for pump wave interaction heights in the region of 240-250 km in daytime conditions. The results are in agreement with previous measurements made by other techniques. We discuss some problems with the method and suggest improvements for future experiments.

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Section: Instrumentationmentioning

confidence: 99%

Multi-frequency HF radar measurements of artificial F-region field-aligned irregularities

et al. 2004

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“…Therefore, it is not possible with the data set used in this study to determine the plasma frequency for every individual SuperDARN frequency shift, so a statistical analysis of velocities before and after frequency changes was performed instead. In future studies, analysis of SuperDARN stereo [Lester et al, 2004] or sounding [Hughes et al, 2002] operation modes may allow real-time analysis of refractive index and SuperDARN velocity improvements.…”

Section: Typical Scan-to-scan Variation Of Velocity Measured By Supermentioning

confidence: 99%

Improvement of HF coherent radar line-of-sight velocities by estimating the refractive index in the scattering volume using radar frequency shifting

et al. 2011

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[1] Measurements of ionospheric drift velocities using HF coherent scatter radars, such as SuperDARN, are generally underestimated because the refractive index in the scattering volume has not been taken into account. Refractive index values evaluated from electron density measurements, international reference ionosphere predictions, or elevation angle measurements have been applied to SuperDARN velocities in past studies. However, the SuperDARN velocities so obtained were, on average, statistically lower than velocities measured by other instruments. One possible explanation for this underestimation is that HF coherent scatter preferentially occurs in regions of the ionosphere where the scattering cross section is largest, and such regions are characterized by small-scale structures which have higher-than-average electron densities. This was not accounted for in past studies because the refractive index estimates used were from large scale and therefore smoothed estimates of electron density. In this paper, a new method of estimating the actual electron density (or plasma frequency) at the location of SuperDARN scatter (instead of the larger-scale background electron density) is presented. This method takes advantage of the frequency shifts which occur in normal SuperDARN operations. If it is assumed that, on average, the actual ionospheric drift velocity and plasma frequency are roughly constant before and after a shift in frequency, any change in measured velocity as SuperDARN changes frequency is due to a change in refractive index. An analysis of the change in the measured velocity resulting from each shift in frequency gives an experimentally based estimate of the electron density in the scattering volume. A statistical analysis of essentially all frequency shifts by SuperDARN and the estimated electron densities in the scattering volume has been performed. The resulting electron densities are appreciably higher than previous methods to estimate electron density predict. Application of this new method to velocity comparisons between SuperDARN and other instruments results in agreement between the HF radar and non-HF radar velocities for the first time. This new method allows for the first direct measurements of electron densities in the exact locations where the cross section for SuperDARN scatter maximizes.

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“…CUTLASS (Cooperative UK Twin Located Auroral Sounding System) is a pair of HF coherent backscatter radar located in Finland and Iceland and forms part of the SuperDARN array (Greenwald et al, 1995;Milan et al, 1997;Lester et al, 2004). In the course of the experiment CUTLASS operated at three frequencies of about 10, 11.5 and 13.2 MHz.…”

Section: Experimental Arrangementmentioning

confidence: 99%

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

Blagoveshchenskaya

Carlson²,

Kornienko

et al. 2009

Ann. Geophys.

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Abstract. Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency f H was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency was just below the third electron gyro harmonic frequency, while both the HF pump beam and UHF radar beam were directed towards the magnetic zenith (MZ). The HF pump-induced phenomena were diagnosed with several instruments: the bi-static HF radio scatter on the LondonTromsø-St. Petersburg path, the CUTLASS radar in Hankasalmi (Finland), the European Incoherent Scatter (EIS-CAT) UHF radar at Tromsø and the Tromsø ionosonde (dynasonde). The results show thermal electron excitation of the HF-induced striations seen simultaneously from HF bi-static scatter and CUTLASS radar observations, accompanied by increases of electron temperature when the heater frequency was near and then above the critical frequency of the F2 layer by up to 0.4 MHz. An increase of the electron density up to 25% accompanied by strong HF-induced electron heating was observed, only when the heater frequency was near the critical frequency and just below the third electron gyro harmonic frequency. It is concluded that the combined effect of upper hybrid resonance and gyro resonance at the same altitude gives rise to strong electron heating, the excitation of Correspondence to: N. F. Blagoveshchenskaya (nataly@aari.nw.ru) striations, HF ray trapping and extension of HF waves to altitudes where they can excite Langmuir turbulence and fluxes of electrons accelerated to energies that produce ionization.

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Stereo CUTLASS - A new capability for the SuperDARN HF radars

Cited by 89 publications

References 38 publications

Multi-frequency HF radar measurements of artificial F-region field-aligned irregularities

Multi-frequency HF radar measurements of artificial F-region field-aligned irregularities

Improvement of HF coherent radar line-of-sight velocities by estimating the refractive index in the scattering volume using radar frequency shifting

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

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