[1] Plasma lines excited by a powerful, high-frequency (HF) radio wave are studied using data obtained with an ultrahigh frequency (UHF) radar at HAARP (High Frequency Active Auroral Research Program) from 3 to 5 February 2005. Of particular interest is persistent enhancement of the radar backscatter power during HF on at several HF frequencies. The persistent enhancement is induced with the HF...

[1] Experimental observations of ELF/VLF waves generated using the dual‐beam heating capability of the High frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska, are compared with the predictions of an ionospheric HF heating model that accounts for the simultaneous propagation and absorption of multiple HF beams. The model output is used to assess three properties ...

High-Frequency (HF) radars are operated in the 3-30 MHz frequency range and have been used for several decades now. Sky-wave systems are able to keep large areas under surveillance, e.g. the whole northern coast of Australia. Some of these systems have caused severe interference to other radio services like the Russian ”Woodpecker”. Currently, a network of ground-wave HF radars is beeing instal...

Experimental results from three ionospheric HF pumping experiments in overdense E or F regions are summarized. The experiments were conducted by the use of the EISCAT HF Heating facility located near Tromsø, Norway, allowing HF pumping the ionosphere in a near geomagnetic field-aligned direction. Distinctive features related to auroral activations in the course of the experiments are identified...

Large electron temperature increases (~3000 K) in the ionospheric F-region, produced by powerful HF wave injection, were measured using the EISCAT incoherent scatter radar near Tromsø, Norway, on 7 October 1999. Magnetic fieldaligned measurements showed HF-initiated ion outflows reaching several hundred ms at 580 km. When scanning the radar antenna from field-aligned (77.2o southward) to vertic...

Since the middle of 1995, an HF Doppler sounder has been running almost continuously in northern Norway, with the receiver at Ramfjordmoen and the transmitter at Seljelvnes. Concurrent operation of the EISCAT UHF radar in common programme (CP-1) mode has made it possible to study the ionospheric signature of a magnetospheric ULF wave. These are the ®rst results of such wave signatures observed ...

The CUTLASS (Co-operative UK Twin Located Auroral Sounding System) Finland HF radar, whilst operating in a high spatial and temporal resolution mode, has measured the ionospheric signature of a naturally occurring ULF wave in scatter arti®cially generated by the Tromsù Heater. The wave had a period of 100 s and exhibited curved phase fronts across the heated volume (about 180 km along a single ...

The capability of phased-array HF radar systems to sample the spatial distribution of wave energy is investigated in different storm scenarios and coastal configurations. First, a formulation introduced by D. E. Barrick to extract significant wave height Hs from backscatter Doppler spectra was calibrated and subsequently tested (to assess bias and uncertainty) with data from seven different buo...