Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars
نویسندگان
چکیده
Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north) of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-ofview that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter.
منابع مشابه
Initial backscatter occurrence statistics from the CUTLASS HF radars
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 ionosph...
متن کاملValidation of the CUTLASS HF radar gravity wave observing capability using EISCAT CP-1 data
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 o...
متن کاملHigh-latitude observations of impulse-driven ULF pulsations in the ionosphere and on the ground
We report the simultaneous observation of 1.6– 1.7 mHz pulsations in the ionospheric F-region with the CUTLASS bistatic HF radar and an HF Doppler sounder, on the ground with the IMAGE and SAMNET magnetometer arrays, and in the upstream solar wind. CUTLASS was at the time being operated in a special mode optimized for high resolution studies of ULF waves. A novel use is made of the ground retur...
متن کاملOn the altitude dependence of the spectral characteristics of decametre-wavelength E region backscatter and the relationship with optical auroral forms
Observations of E region backscatter by the Iceland East SuperDARN HF radar from the 30 minute period 2330 to 2400 UT on 13 September 1999 are presented, along with simultaneous observations of auroral luminosity from two all-sky cameras. Interferometric techniques are employed to estimate the altitude of origin of each echo observed by the radar. Under investigation is a region of backscatter ...
متن کاملULF waves with drift resonance and drift-bounce resonance energy sources as observed in artificially-induced HF radar backscatter
HF radar backscatter which has been artificiallyinduced by a high power RF facility such as the EISCAT heater at Tromsø has been demonstrated to provide ionospheric electric field data of unprecedented temporal resolution and accuracy. Here such data are used to investigate ULF wave processes observed by the CUTLASS HF radars. Within a short period of time during a single four hour experiment t...
متن کامل