Whistler Wave Interactions with Space Plasmas during
HF Heating of the Ionosphere at Arecibo
M. C. Lee1, M. J. Starks1, W. J. Burke2, S. P. Kuo3
M. P. Sulzer4, R. J. Riddolls1, A. X. Zhang1
We demonstrate that signals at 28.5 kHz emitted from the Naval (NAU) transmitter
in Puerto Rico eectively couple into ionospheric ducts, induced/enhanced by the Arecibo
HF heater, and propagate into the conjugate hemisphere as ducted whistlers. Also
presented are suspected radar detections of whistler-triggered electron precipitation events.
NAU-generated whistlers have intensities sucient to parametrically excite lower hybrid
waves and 10-m scale ionospheric irregularities over Arecibo. Subsequent heating of
electrons and ions by the lower hybrid waves yields a chain of ionospheric plasma eects,
such as airglow, short-scale density depletions, and plasma line enhancements in a range
of altitudes which far exceeds that aected by the HF heater. Whistler contamination
from NAU overriding some heater-induced eects may account for apparent discrepancies
between results reported from Arecibo and other heater sites.
1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge,
2. Air Force Research Laboratory, Hanscom Air Force Base, Massachusetts 01731.
3. Polytechnic University, Farmingdale, New York 11735.
4. Arecibo Observatory, Arecibo, Puerto Rico 00612.
Intense VLF whistler waves from transmitters or lightning discharges parametrically
excite lower hybrid waves and eld-aligned zero-frequency plasma density irregularities in
the ionosphere [Lee and Kuo, 1984]. The excited ionospheric density irregularities have
scale sizes of 10 m and align with the geomagnetic eld lines to form laments. The
lower hybrid waves can accelerate electrons and ions along and across the geomagnetic
eld, respectively, generating non-Maxwellian distribution functions [Lynch et al., 1994]
capable of exciting airglow. In fact, airglow eects were observed in coincidence with the