HR: 0800h
AN: SA21C-0377    [Abstracts]
TI: ELF/VLF Waves Generated by an Artificially-Modulated Auroral Electrojet Above the HAARP HF Transmitter
AU: * Moore, R C
EM: berto@stanford.edu
AF: Stanford University, 350 Serra Mall, Rm 037, Stanford, CA 94305
AU: Inan, U S
EM: inan@stanford.edu
AF: Stanford University, 350 Serra Mall, Rm 355, Stanford, CA 94305
AU: Bell, T F
EM: bell@nova.stanford.edu
AF: Stanford University, 350 Serra Mall, Rm 357, Stanford, CA 94305
AB: Naturally-forming, global-scale currents, such as the polar electrojet current and the mid-latitude dynamo, have been used as current sources to generate electromagnetic waves in the Extremely Low Frequency (ELF) and Very Low Frequency (VLF) bands since the 1970's. While many short-duration experiments have been performed, no continuous multi-week campaign data sets have been published providing reliable statistics for ELF/VLF wave generation. In this paper, we summarize the experimental data resulting from multiple ELF/VLF wave generation campaigns conducted at the High-frequency Active Auroral Research Project (HAARP) HF transmitter in Gakona, Alaska. For one 14-day period in March, 2002, and one 24-day period in November, 2002, the HAARP HF transmitter broadcast ELF/VLF wave generation sequences for 10 hours per day, between 0400 and 1400 UT. Five different modulation frequencies broadcast separately using two HF carrier frequencies are examined at receivers located 36, 44, 147, and 155 km from the HAARP facility. Additionally, a continuous 24-hour transmission period is analyzed to compare day-time wave generation to night-time wave generation. Lastly, a power-ramping scheme was employed to investigate possible thresholding effects at the wave-generating altitude. Wave generation statistics are presented along with source-region property calculations performed using a simple model.
DE: 6924 Interferometry
DE: 2403 Active experiments
DE: 2407 Auroral ionosphere (2704)
DE: 2409 Current systems (2708)
DE: 2487 Wave propagation (6934)
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting