Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

Milan, S. E.; Jones, T. B.; Robinson, T. R.; Thomas, E. C.; Yeoman, T. K.

doi:10.1007/s00585-997-0029-y

Cited by 88 publications

(148 citation statements)

References 10 publications

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“…equatorward of ) the radars as a consequence of a rear lobe in the antenna patterns and favourable propagation conditions at mid latitudes. Interferometer information can distinguish between front and rear backscatter as backscatter from in front of the radars has elevation angles which tend to decrease with increasing range (consistent with HF propagation characteristics) and backscatter from behind the radars has elevation angles which increase with range (due to 2p ambiguities in determining the phase delay, Milan et al, 1997). Thus, comparing elevation angle occurrence distributions from di erent ranges it is possible to identify two populations of observations, which increase and decrease in elevation angle with increasing range.…”

Section: Ground Backscattermentioning

confidence: 86%

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Initial backscatter occurrence statistics from the CUTLASS HF radars

et al. 1997

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Abstract. A statistical study of the occurrence of ground and ionospheric backscatter within the ®elds-of-view of the CUTLASS HF radars, at an operating frequency of 10 MHz, during the ®rst 20 months of operation has been undertaken. The diurnal variation of the occurrence of backscatter and the range at which such backscatter is observed is found to be highly dependent on seasonal changes of the ionospheric electron density in both the E and F region, determined from ionosonde observations. In general, ionospheric backscatter is observed at far ranges during the local day in winter months and at near ranges during the local night in summer months. The Iceland radar observes more nearrange E region backscatter than the Finland radar as a consequence of its more zonal look-direction. The dependence of the occurrence of backscatter on geomagnetic activity and radar operating frequency are also investigated. The occurrence of ground and ionospheric backscatter is discussed in terms of HF propagation modes and ionospheric electron densities as well as geophysical processes. A brief assessment of the possible impact of solar cycle variations on the observations is made and frequency management is discussed. Such a study, with its focus on the`instrumental' aspect of backscatter occurrence, is essential for a full interpretation of HF coherent radar observations.

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Section: Ground Backscattermentioning

confidence: 86%

“…A previous study of the interferometer results of the CUTLASS radars (Milan et al, 1997) indicated that a signi®cant proportion of ground backscatter originates behind (i.e. equatorward of ) the radars as a consequence of a rear lobe in the antenna patterns and favourable propagation conditions at mid latitudes.…”

Section: Ground Backscattermentioning

confidence: 99%

Initial backscatter occurrence statistics from the CUTLASS HF radars

et al. 1997

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“…• Milan and identified population vi echoes that appeared to have similar characteristics to population i but with a reversed Doppler shift; these are now understood to be population i echoes that have been observed in the rear field-of-view of the radar (Milan et al 1997) when the electrojet is located at extremely low latitudes.…”

Section: E-region Ionospheric Irregularitiesmentioning

confidence: 95%

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions

et al. 2007

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The Super Dual Auroral Radar Network (SuperDARN) has been operating as an international co-operative organization for over 10 years. The network has now grown so that the fields of view of its 18 radars cover the majority of the northern and southern hemisphere polar ionospheres. SuperDARN has been successful in addressing a wide range of scientific questions concerning processes in the magnetosphere, ionosphere,

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“…2, and the latest starting around 15:00 UT, indicate that these waves were travelling away from the radar. This apparent anomaly was resolved by Milan et al (1997) who proposed that when the forward-directed beams are looking at the ionosphere when it is still in darkness, the backward-looking side lobes are able to receive signals propagating via the sunlit ionosphere at lower latitudes. The radar is su ciently sensitive to detect these signals above the noise threshold.…”

Section: The Cutlass Iceland and Finland Radarsmentioning

confidence: 99%

Validation of the CUTLASS HF radar gravity wave observing capability using EISCAT CP-1 data

et al. 1998

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Abstract. Quasi-periodic¯uctuations in the returned ground-scatter power from the SuperDARN HF radars have been linked to the passage of medium-scale gravity waves. We have applied a technique that extracts the ®rst radar range returns from the F-region to study the spatial extent and characteristics of these waves in the CUTLASS ®eld-of-view. Some ray tracing was carried out to test the applicability of this method. The EISCAT radar facility at Tromsù is well within the CUTLASS ®eld-of-view for these waves and provides a unique opportunity to assess independently the ability of the HF radars to derive gravity wave information. Results from 1st March, 1995, where the EISCAT UHF radar was operating in its CP-1 mode, demonstrate that the radars were in good agreement, especially if one selects the electron density variations measured by EISCAT at around 235 km. CUTLASS and EISCAT gravity wave observations complement each other; the former extends the spatial ®eld of view considerably, whilst the latter provides detailed vertical information about a range of ionospheric parameters.

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Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

Cited by 88 publications

References 10 publications

Initial backscatter occurrence statistics from the CUTLASS HF radars

Initial backscatter occurrence statistics from the CUTLASS HF radars

A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions

Validation of the CUTLASS HF radar gravity wave observing capability using EISCAT CP-1 data

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