On the occurrence of ground observations of ELF/VLF magnetospheric amplification induced by the HAARP facility

Abstract

[1] The ionospheric heating facility of the High Frequency Active Auroral Research Program (HAARP) has been used extensively in the last 3 years for injection of ELF/VLF waves into the magnetosphere via modulated heating of the overhead auroral electrojet currents. Of particular interest are waves that are observed to be nonlinearly amplified after interaction with hot plasma electrons in the Earth's radiation belts. Past results have shown HAARP to be an effective platform for controlled studies of wave particle interactions in the Earth's magnetosphere. A summary of the experimental results is provided in the context of dependencies on geomagnetic conditions and transmitter parameters. It is deduced that the primary variable that is associated with successful ground observations of HAARP-induced magnetospheric amplification is availability of magnetospheric wave guiding structures. Such structures are found to be most prevalent under quiet geomagnetic conditions following a disturbance when the plasmapause extends to the latitude of the HAARP facility or higher. Strong electrojet currents and high amplitudes of generated ELF/VLF signals observed on the ground are poor indicators of observation probability on a day to day basis although variation of these variables can be important on minute and second timescales.

Remote Sensing of Radiation Belt Energetic Electrons Using Lightning Triggered Upper Band Chorus

“…Lower band chorus being more often observed than upper band chorus is well documented (Meredith et al, 2001;Tsurutani & Smith, 1974). It is also worth noting that waves from science dedicated transmitters at Siple Station (L = 4.3, 1.5 kW) and HAARP experiment (L = 4.9, less than 0.5 W) both triggered free-running chorus-like emissions below the half cyclotron frequency, but those above observed to be triggered only by Siple transmitter (Carpenter & Bao, 1983;Gołkowski et al, 2011;Sazhin & Hayakawa, 1992). They argue that the most likely candidates for the substorm-independent chorus emissions are lightning-generated whistler and VLF signals from groundbased transmitters.…”

Excitation of Chirping Whistler Waves in a Laboratory Plasma

“…Such experimental testing is difficult to perform in space, since spacecraft do not generally have access to the source distribution of electrons that originally generated the waves, but can be readily performed in a laboratory setting, which is the motivation of the present study. Similarly, previous attempts to remotely excite artificial whistler waves have been made in the Earth's near-space environment and have yielded interesting results [13,14], but have been difficult to probe and control.…”

Effects of the Hall Conductivity in Ionospheric Heating Experiments

“…Two of the most efficient methods described in the literature include "beam painting" and geometric modulation techniques. The injection of extremely-low frequency (ELF)/very-low frequency (VLF) waves into the magnetosphere by the modulated heating of the electrojet by the High Altitude Active Research Program (HAARP) facility in Alaska has been extensively studied by Papadopoulos et al (2003), Golkowski et al (2008, 2011), and Cohen et al (2010. The entire process is modulated with the frequency of the generated wave.…”