HR: 14:20h
AN: SA53C-02    [Abstracts]
TI: First Observations of Artificially-Generated ULF Magnetic Pulsations at HAARP
AU: * Parent, A
EM: aparent@phys.ualberta.ca
AF: University of Alberta, Department of Physics Room #238 CEB 11322-89 Avenue, Edmonton, AB T6E1P4, Canada
AU: Mann, I R
EM: imann@phys.ualberta.ca
AF: University of Alberta, Department of Physics Room #238 CEB 11322-89 Avenue, Edmonton, AB T6E1P4, Canada
AU: Kosch, M
EM: m.kosch@lancaster.ac.uk
AF: Lancaster University, Department of Communication Systems InfoLab21 , Lancaster, LA14WA, United Kingdom
AU: McCarrick, M
EM: mike.mccarrick@baesystems.com
AF: BAE Systems, Washington, DC, United States
AU: Pedersen, T
EM: todd.pedersen@hanscom.af.mil
AF: Air Force Research Laboratory, Space Vehicles Directorate Hanscom AFB, MA 01731, United States
AU: Hayashi, K
EM: hayashi@geoph.s.u-tokyo-ac.jp
AF: University of Tokyo (retired), 3-30-11 Ohtsugaoka, Chiba , 277-0921, Japan
AB: Over three separate intervals, active ionospheric heating experiments with ULF-modulated power in the 0.1 to 5.0 Hz range were conducted at the HAARP HF heater facility near Gakona, Alaska. On August 23, 2005, 3.2 MHz heating was carried out from 02:45 to 05:00 UT. During the active experiments of March 20 and 21, 2006, a 3.04 MHz frequency was used to heat between 05:00 and 10:00 UT. Each of the intervals involved ULF-modulation of the heater power in repeating sequences that stepped through frequencies starting at 0.1 Hz and ending on 3.0 to 6.0 Hz. Analysis of data from the 10 Hz ground-based search coil magnetometer located at HAARP during each experimental interval indicates the presence of ULF wave signals with frequencies that match the stepped ULF modulation frequencies of the heater power. The search coil instrument is located close (less than 2 km) to the heater array, which means caution must be taken in interpreting the results as an ionospheric signal. However, the magnetic ULF wave signal power varies strongly in the H and D components throughout each experiment as the stepped modulation frequency sequences are repeated, and signal amplitude is also observed to increase significantly during a narrow-band structured Pc1 pearl event that developed during the experiment of March 21, 2006. This suggests that conditions in the ionosphere changed, making them more amenable to artificial generation of ULF waves. Using the magnetometer data and other ionospheric diagnostic instruments, we present the case that the waves observed at HAARP were generated actively by ionospheric modification over the intervals described above. The results suggest that future opportunities to repeat similar ULF experiments at HAARP should include the additional deployment of multiple search coils in a wider area surrounding the heating facility. Beyond our interest in investigating the processes involved in generating artificial ULF waves in the ionosphere, future experiments will focus upon attempting to actively produce ULF waves that may stimulate the Ionospheric Alfven Resonator (IAR).
DE: 2403 Active experiments
DE: 2704 Auroral phenomena (2407)
DE: 6964 Radio wave propagation
DE: 7836 MHD waves and instabilities (2149, 2752, 6050)
DE: 7944 Ionospheric effects on radio waves
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly