Chirped incoherent scatter radar observations of the HF-modified ionosphere

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5194088

Isham, B C

High power high frequency (HF) radio wave modification experiments were conducted in the ionosphere above Arecibo in 1986, 1987, and 1988 and observed using chirped incoherent scatter radar diagnostics. The heating duty cycle was normally 30-s-on/30-s-off, although the on and off times were occasionally varied and CW was used during one experiment. The data show that the observations of Muldrew and Showen (1977) and of Birkmayer et al. (1986), which suggests that heater enhanced waxes are trapped inside plasma density depletions located near the O mode cutoff, can be readily duplicated under typical ionospheric conditions above Arecibo. High time resolution (5 ms) observations indicate that the HF line appears at the O mode cutoff within 20 ms of heater turn-on with no subsequent development in height. Simultaneous daytime chirped and unchirped observations show the existence of additional layers of excited waves located between 1 and 3 km below the usual region and normally appearing about 10 s after heater turn-on. The appearance of these new layers may be associated with the creation of a new resonance at the height where the heating frequency f{sub hf} equals the upper hybrid frequency. Nighttime observations also show several layers of enhanced plasma lines spread over a 3-km height range below the matching height. This phenomena appears to depend strongly on the incident HF heating power. Implications of these results for current theories of heating are discussed, and specific further observations are recommended.

• Research Organization: Cornell Univ., Ithaca, NY (United States)
• OSTI ID: 5194088
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DIAGNOSTIC TECHNIQUES
EARTH ATMOSPHERE
ELECTROMAGNETIC RADIATION
HEATING
IONOSPHERE
MEASURING INSTRUMENTS
MODIFICATIONS
PLANETARY IONOSPHERES
PLASMA DENSITY
PLASMA HEATING
RADAR
RADIATIONS
RADIOWAVE RADIATION
RANGE FINDERS
RECOMMENDATIONS
RESOLUTION
TIME RESOLUTION
TIMING PROPERTIES